<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2021 Workiva-->
<!--r:0a91717b-5b9a-4470-a716-9c00214a8bdd,g:f2a8631c-ae82-4a44-9090-35d7005e9a98-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:roleRef roleURI="http://mckesson123.com/role/CoverPage" xlink:type="simple" xlink:href="mck-20210331.xsd#CoverPage"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/CoverPage" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/CONSOLIDATEDSTATEMENTSOFOPERATIONS" xlink:type="simple" xlink:href="mck-20210331.xsd#CONSOLIDATEDSTATEMENTSOFOPERATIONS"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/CONSOLIDATEDSTATEMENTSOFOPERATIONS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_400a0b30-ec91-493a-b4f3-48e81c610426" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare_61d00fb5-347d-4dd0-8c88-d33ce6f489af" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_EarningsPerShareDiluted_400a0b30-ec91-493a-b4f3-48e81c610426" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare_61d00fb5-347d-4dd0-8c88-d33ce6f489af" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare_6dfb119e-731a-496c-8989-5bb4273fd8ee" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_EarningsPerShareDiluted_400a0b30-ec91-493a-b4f3-48e81c610426" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare_6dfb119e-731a-496c-8989-5bb4273fd8ee" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_afec0515-4d32-44b2-91ee-0fce800c3699" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingExpenses"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedCostIncurredCost_7e2c028f-782d-4976-a76e-909bb998578e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestructuringAndRelatedCostIncurredCost"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingExpenses_afec0515-4d32-44b2-91ee-0fce800c3699" xlink:to="loc_us-gaap_RestructuringAndRelatedCostIncurredCost_7e2c028f-782d-4976-a76e-909bb998578e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LegalFees_fdb265e3-28ec-4f3a-8ff6-cbb271ef5572" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LegalFees"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingExpenses_afec0515-4d32-44b2-91ee-0fce800c3699" xlink:to="loc_us-gaap_LegalFees_fdb265e3-28ec-4f3a-8ff6-cbb271ef5572" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_9605ae52-572e-4c27-bd2d-bb961f3e38bd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingExpenses_afec0515-4d32-44b2-91ee-0fce800c3699" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_9605ae52-572e-4c27-bd2d-bb961f3e38bd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_7eaf9e86-351d-4f72-bc43-dc7cb2794983" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpense"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingExpenses_afec0515-4d32-44b2-91ee-0fce800c3699" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_7eaf9e86-351d-4f72-bc43-dc7cb2794983" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_25ea3883-8d26-40bf-b374-6cf0e095a16e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsPerBasicShare_e2cf6313-ba40-4820-b9a0-8d18755076d6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsPerBasicShare"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_EarningsPerShareBasic_25ea3883-8d26-40bf-b374-6cf0e095a16e" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsPerBasicShare_e2cf6313-ba40-4820-b9a0-8d18755076d6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare_a39af1a1-6bee-48a4-8b38-187517fc3a8b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_EarningsPerShareBasic_25ea3883-8d26-40bf-b374-6cf0e095a16e" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare_a39af1a1-6bee-48a4-8b38-187517fc3a8b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_30d97216-afee-4845-ab1a-41bf3c3cd681" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossProfit_0552a9ad-b054-4533-b553-29316b571c3a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GrossProfit"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingIncomeLoss_30d97216-afee-4845-ab1a-41bf3c3cd681" xlink:to="loc_us-gaap_GrossProfit_0552a9ad-b054-4533-b553-29316b571c3a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_429375d5-3ebd-4d2d-a2f1-28cbc74dd032" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingExpenses"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingIncomeLoss_30d97216-afee-4845-ab1a-41bf3c3cd681" xlink:to="loc_us-gaap_OperatingExpenses_429375d5-3ebd-4d2d-a2f1-28cbc74dd032" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossProfit_4b5c05dd-5364-435d-b908-4b17ccc5f0dd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GrossProfit"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_89554825-1a8a-413b-8dc2-fdd81d591de9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_GrossProfit_4b5c05dd-5364-435d-b908-4b17ccc5f0dd" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_89554825-1a8a-413b-8dc2-fdd81d591de9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_3944c541-3b52-4931-8284-9e1430fba6b9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_GrossProfit_4b5c05dd-5364-435d-b908-4b17ccc5f0dd" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_3944c541-3b52-4931-8284-9e1430fba6b9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_3c91319b-104b-4943-852b-480f68265ddb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_25d5bff6-5b7d-45f5-a434-94ffbc3a59a4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProfitLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_3c91319b-104b-4943-852b-480f68265ddb" xlink:to="loc_us-gaap_ProfitLoss_25d5bff6-5b7d-45f5-a434-94ffbc3a59a4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_57966660-b639-41f6-942f-43bb034eff7f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_3c91319b-104b-4943-852b-480f68265ddb" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_57966660-b639-41f6-942f-43bb034eff7f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_78c53536-f575-4258-9410-ffeff7e2e1b8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_19028e9b-44d7-4558-bda5-d3c0cd9ddfcf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_78c53536-f575-4258-9410-ffeff7e2e1b8" xlink:to="loc_us-gaap_OperatingIncomeLoss_19028e9b-44d7-4558-bda5-d3c0cd9ddfcf" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_053d2ef3-6b92-446c-9e19-4bd69f2d4ae5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_78c53536-f575-4258-9410-ffeff7e2e1b8" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_053d2ef3-6b92-446c-9e19-4bd69f2d4ae5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_d181c10b-545d-40e2-874b-e0d57e9b7972" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestExpense"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_78c53536-f575-4258-9410-ffeff7e2e1b8" xlink:to="loc_us-gaap_InterestExpense_d181c10b-545d-40e2-874b-e0d57e9b7972" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_IncomeLossfromEquityMethodInvestmentsIncludingOtherThanTemporaryImpairmentandTransactionCosts_7ff8ef25-d698-454c-ac7e-849859fd4254" xlink:href="mck-20210331.xsd#mck_IncomeLossfromEquityMethodInvestmentsIncludingOtherThanTemporaryImpairmentandTransactionCosts"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_78c53536-f575-4258-9410-ffeff7e2e1b8" xlink:to="loc_mck_IncomeLossfromEquityMethodInvestmentsIncludingOtherThanTemporaryImpairmentandTransactionCosts_7ff8ef25-d698-454c-ac7e-849859fd4254" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_dd16c86c-62a4-4911-a2f0-9054a8094a55" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_52fa6006-40a4-4ac0-8431-707cbfa26127" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_dd16c86c-62a4-4911-a2f0-9054a8094a55" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_52fa6006-40a4-4ac0-8431-707cbfa26127" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_a438ca49-2ebe-4722-aca5-2a8b762512f9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_dd16c86c-62a4-4911-a2f0-9054a8094a55" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_a438ca49-2ebe-4722-aca5-2a8b762512f9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_a3ad23ae-9da2-44db-bb5a-12d470b1231c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProfitLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax_b6d1a44a-ede8-4443-91e6-f6c2bc5cf8c4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ProfitLoss_a3ad23ae-9da2-44db-bb5a-12d470b1231c" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax_b6d1a44a-ede8-4443-91e6-f6c2bc5cf8c4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_193ef560-e690-4d61-853c-42eb3835360a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ProfitLoss_a3ad23ae-9da2-44db-bb5a-12d470b1231c" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_193ef560-e690-4d61-853c-42eb3835360a" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOMELOSS" xlink:type="simple" xlink:href="mck-20210331.xsd#CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOMELOSS"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOMELOSS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_713ddad9-2e23-462c-8f98-3d5ec55d08ef" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_0acfda6d-b08c-43b3-91a4-7136a979d9e3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_713ddad9-2e23-462c-8f98-3d5ec55d08ef" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_0acfda6d-b08c-43b3-91a4-7136a979d9e3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_d405f272-cdf6-4478-b080-f05c85615e19" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProfitLoss"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_713ddad9-2e23-462c-8f98-3d5ec55d08ef" xlink:to="loc_us-gaap_ProfitLoss_d405f272-cdf6-4478-b080-f05c85615e19" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_11ee9bfc-631d-4702-ad01-448c1302d6b0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_4fbdead4-3374-45f0-8d31-973c2e269bff" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_11ee9bfc-631d-4702-ad01-448c1302d6b0" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_4fbdead4-3374-45f0-8d31-973c2e269bff" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax_de707637-d53b-4b73-83ae-64e1524b55e2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_11ee9bfc-631d-4702-ad01-448c1302d6b0" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax_de707637-d53b-4b73-83ae-64e1524b55e2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax_b1065790-5248-4bb7-826f-08fe32381c88" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_11ee9bfc-631d-4702-ad01-448c1302d6b0" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax_b1065790-5248-4bb7-826f-08fe32381c88" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax_fc43a6d3-6846-4562-be3d-89ccaab78f1e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_a4994835-fd34-47f6-9c06-58f6313e1a72" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTax_fc43a6d3-6846-4562-be3d-89ccaab78f1e" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_a4994835-fd34-47f6-9c06-58f6313e1a72" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest_8529e992-163e-4e75-9fe7-7355106279d2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTax_fc43a6d3-6846-4562-be3d-89ccaab78f1e" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest_8529e992-163e-4e75-9fe7-7355106279d2" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/CONSOLIDATEDBALANCESHEETS" xlink:type="simple" xlink:href="mck-20210331.xsd#CONSOLIDATEDBALANCESHEETS"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/CONSOLIDATEDBALANCESHEETS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_07afc445-c460-42ee-9832-9cec6b939399" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_bd58abe8-33d8-4d76-a914-b95001a5f090" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_07afc445-c460-42ee-9832-9cec6b939399" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_bd58abe8-33d8-4d76-a914-b95001a5f090" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_a071c402-5622-47ef-b567-6fb60539d4e6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_07afc445-c460-42ee-9832-9cec6b939399" xlink:to="loc_us-gaap_LiabilitiesCurrent_a071c402-5622-47ef-b567-6fb60539d4e6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_dab5fbec-c3c0-41f7-b03a-27cd5a08748a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_07afc445-c460-42ee-9832-9cec6b939399" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_dab5fbec-c3c0-41f7-b03a-27cd5a08748a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_deb83c22-813c-46d6-a1c8-7170fabd9220" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_07afc445-c460-42ee-9832-9cec6b939399" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_deb83c22-813c-46d6-a1c8-7170fabd9220" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationReserveNoncurrent_80e7e0c0-29b9-41bf-82da-fe6b24c5bbff" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LitigationReserveNoncurrent"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_07afc445-c460-42ee-9832-9cec6b939399" xlink:to="loc_us-gaap_LitigationReserveNoncurrent_80e7e0c0-29b9-41bf-82da-fe6b24c5bbff" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_9c8998d2-b943-44db-be7f-4804a56f8d51" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_07afc445-c460-42ee-9832-9cec6b939399" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_9c8998d2-b943-44db-be7f-4804a56f8d51" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_b306d90a-9306-497c-ac08-9386768e1db2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommitmentsAndContingencies"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_07afc445-c460-42ee-9832-9cec6b939399" xlink:to="loc_us-gaap_CommitmentsAndContingencies_b306d90a-9306-497c-ac08-9386768e1db2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RedeemableNoncontrollingInterestEquityCommonCarryingAmount_594add95-058c-44a5-9943-4d6875c22e12" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RedeemableNoncontrollingInterestEquityCommonCarryingAmount"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_07afc445-c460-42ee-9832-9cec6b939399" xlink:to="loc_us-gaap_RedeemableNoncontrollingInterestEquityCommonCarryingAmount_594add95-058c-44a5-9943-4d6875c22e12" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_78fe4188-8837-4126-a023-a26fbe8325b6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_07afc445-c460-42ee-9832-9cec6b939399" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_78fe4188-8837-4126-a023-a26fbe8325b6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_b67ed2ab-1692-431f-827a-2b420814a23d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_2c305f7d-8e43-4c1d-850e-cf788ee6014c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_b67ed2ab-1692-431f-827a-2b420814a23d" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_2c305f7d-8e43-4c1d-850e-cf788ee6014c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivablesNetCurrent_a21f474a-dc3b-4a43-9c6c-ada66c9e491d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReceivablesNetCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_b67ed2ab-1692-431f-827a-2b420814a23d" xlink:to="loc_us-gaap_ReceivablesNetCurrent_a21f474a-dc3b-4a43-9c6c-ada66c9e491d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNet_7eaf3696-6ce9-486b-800b-86f4db9811d5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryNet"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_b67ed2ab-1692-431f-827a-2b420814a23d" xlink:to="loc_us-gaap_InventoryNet_7eaf3696-6ce9-486b-800b-86f4db9811d5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_d8e775fb-4fbd-4854-8d9a-a0ad4ddd6b51" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_b67ed2ab-1692-431f-827a-2b420814a23d" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_d8e775fb-4fbd-4854-8d9a-a0ad4ddd6b51" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_be8dc754-810e-40cc-af9a-0f5c8e5506f3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_b67ed2ab-1692-431f-827a-2b420814a23d" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_be8dc754-810e-40cc-af9a-0f5c8e5506f3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_1f119fc8-b332-4df9-ae07-3660fdc91716" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockValue_e4876faa-7e60-47e3-9004-82579dbbc421" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockValue"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_1f119fc8-b332-4df9-ae07-3660fdc91716" xlink:to="loc_us-gaap_PreferredStockValue_e4876faa-7e60-47e3-9004-82579dbbc421" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_c6d8cb90-4940-4981-9d8c-4ea307e36c85" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockValue"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_1f119fc8-b332-4df9-ae07-3660fdc91716" xlink:to="loc_us-gaap_CommonStockValue_c6d8cb90-4940-4981-9d8c-4ea307e36c85" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapital_5b091c13-450d-4a04-9e30-ad8c8c8e79fd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdditionalPaidInCapital"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_1f119fc8-b332-4df9-ae07-3660fdc91716" xlink:to="loc_us-gaap_AdditionalPaidInCapital_5b091c13-450d-4a04-9e30-ad8c8c8e79fd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_db6f8ce3-9fb7-4147-9f91-177071d4f1f9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_1f119fc8-b332-4df9-ae07-3660fdc91716" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_db6f8ce3-9fb7-4147-9f91-177071d4f1f9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_8005aea8-d7c1-479f-b752-03f021905b6a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_1f119fc8-b332-4df9-ae07-3660fdc91716" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_8005aea8-d7c1-479f-b752-03f021905b6a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValue_04605c38-1290-4647-b9a7-995d7737b4a8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TreasuryStockValue"/>
    <link:calculationArc order="6" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_1f119fc8-b332-4df9-ae07-3660fdc91716" xlink:to="loc_us-gaap_TreasuryStockValue_04605c38-1290-4647-b9a7-995d7737b4a8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_be9af410-2d1e-466e-b7d1-b0437b6e4d0a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Assets"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_1395dc9f-0f1a-4029-9fb8-3c77470f32ef" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_be9af410-2d1e-466e-b7d1-b0437b6e4d0a" xlink:to="loc_us-gaap_AssetsCurrent_1395dc9f-0f1a-4029-9fb8-3c77470f32ef" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_084f4a8a-9341-49d8-9480-7c56d5caa706" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_be9af410-2d1e-466e-b7d1-b0437b6e4d0a" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_084f4a8a-9341-49d8-9480-7c56d5caa706" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_3e3399fe-93d0-492f-a214-190cfc75cca6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Goodwill"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_be9af410-2d1e-466e-b7d1-b0437b6e4d0a" xlink:to="loc_us-gaap_Goodwill_3e3399fe-93d0-492f-a214-190cfc75cca6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_2145ac99-5559-4dc3-aba0-b5b1ddbe6f37" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_be9af410-2d1e-466e-b7d1-b0437b6e4d0a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_2145ac99-5559-4dc3-aba0-b5b1ddbe6f37" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_fb2b5fab-dedd-496f-94d1-44d4e597b668" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_be9af410-2d1e-466e-b7d1-b0437b6e4d0a" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_fb2b5fab-dedd-496f-94d1-44d4e597b668" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_f06d8a09-ef53-4453-8212-ed933e5e903f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_be9af410-2d1e-466e-b7d1-b0437b6e4d0a" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_f06d8a09-ef53-4453-8212-ed933e5e903f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_db45c2f7-78f9-43c6-a551-e59cf39f3093" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_e44a2b6e-fc90-46b1-96a4-0d7dfcefee18" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquity"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_db45c2f7-78f9-43c6-a551-e59cf39f3093" xlink:to="loc_us-gaap_StockholdersEquity_e44a2b6e-fc90-46b1-96a4-0d7dfcefee18" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterest_5eb9de32-ad6a-44b0-9149-f995450f2abb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MinorityInterest"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_db45c2f7-78f9-43c6-a551-e59cf39f3093" xlink:to="loc_us-gaap_MinorityInterest_5eb9de32-ad6a-44b0-9149-f995450f2abb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_d6f20b31-0405-4e64-9db7-783eedc78fb6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_e5612088-f2d4-4f2c-a94e-8be0ff9a40c5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_d6f20b31-0405-4e64-9db7-783eedc78fb6" xlink:to="loc_us-gaap_AccountsPayableCurrent_e5612088-f2d4-4f2c-a94e-8be0ff9a40c5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent_5499c0a1-8aa9-494f-bc2a-611cfa7c3c44" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_d6f20b31-0405-4e64-9db7-783eedc78fb6" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent_5499c0a1-8aa9-494f-bc2a-611cfa7c3c44" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_73d26a14-8eb9-4545-aebd-ae84ac08d9a2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_d6f20b31-0405-4e64-9db7-783eedc78fb6" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_73d26a14-8eb9-4545-aebd-ae84ac08d9a2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_81c14756-e624-463c-8083-9f1404ca26d2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_d6f20b31-0405-4e64-9db7-783eedc78fb6" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_81c14756-e624-463c-8083-9f1404ca26d2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_69cac837-b45f-4383-a99f-7dc923ced40b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_d6f20b31-0405-4e64-9db7-783eedc78fb6" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent_69cac837-b45f-4383-a99f-7dc923ced40b" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/CONSOLIDATEDBALANCESHEETSParenthetical" xlink:type="simple" xlink:href="mck-20210331.xsd#CONSOLIDATEDBALANCESHEETSParenthetical"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/CONSOLIDATEDBALANCESHEETSParenthetical" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="simple" xlink:href="mck-20210331.xsd#CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITYParentheticals" xlink:type="simple" xlink:href="mck-20210331.xsd#CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITYParentheticals"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITYParentheticals" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/CONSOLIDATEDSTATEMENTSOFCASHFLOWS" xlink:type="simple" xlink:href="mck-20210331.xsd#CONSOLIDATEDSTATEMENTSOFCASHFLOWS"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/CONSOLIDATEDSTATEMENTSOFCASHFLOWS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_c38742d0-1622-479b-85dc-ff37285f0733" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_8b649835-cd4c-432c-b7e5-385ea9c12325" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProfitLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_c38742d0-1622-479b-85dc-ff37285f0733" xlink:to="loc_us-gaap_ProfitLoss_8b649835-cd4c-432c-b7e5-385ea9c12325" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInReceivables_23aac070-9cda-48f6-ba6f-c2ef7111ccfa" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInReceivables"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_c38742d0-1622-479b-85dc-ff37285f0733" xlink:to="loc_us-gaap_IncreaseDecreaseInReceivables_23aac070-9cda-48f6-ba6f-c2ef7111ccfa" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncashIncomeExpense_184841c3-0579-41ad-927f-0146ee096fd1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherNoncashIncomeExpense"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_c38742d0-1622-479b-85dc-ff37285f0733" xlink:to="loc_us-gaap_OtherNoncashIncomeExpense_184841c3-0579-41ad-927f-0146ee096fd1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet_5c4724eb-fef1-4e4b-aca7-df22147aabf6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_c38742d0-1622-479b-85dc-ff37285f0733" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet_5c4724eb-fef1-4e4b-aca7-df22147aabf6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_IncreaseDecreaseinOperatingLeaseLiabilities_98745992-f076-4fa4-8e3f-72373a5a108e" xlink:href="mck-20210331.xsd#mck_IncreaseDecreaseinOperatingLeaseLiabilities"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_c38742d0-1622-479b-85dc-ff37285f0733" xlink:to="loc_mck_IncreaseDecreaseinOperatingLeaseLiabilities_98745992-f076-4fa4-8e3f-72373a5a108e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_IncomeLossfromEquityMethodInvestmentsIncludingOtherThanTemporaryImpairment_b6dffc0a-374e-4ba8-a45b-61f0c7c06562" xlink:href="mck-20210331.xsd#mck_IncomeLossfromEquityMethodInvestmentsIncludingOtherThanTemporaryImpairment"/>
    <link:calculationArc order="6" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_c38742d0-1622-479b-85dc-ff37285f0733" xlink:to="loc_mck_IncomeLossfromEquityMethodInvestmentsIncludingOtherThanTemporaryImpairment_b6dffc0a-374e-4ba8-a45b-61f0c7c06562" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayable_715b8dbb-60f3-4db4-a6e7-a0de4802f85a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayable"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_c38742d0-1622-479b-85dc-ff37285f0733" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayable_715b8dbb-60f3-4db4-a6e7-a0de4802f85a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInInventories_3e2b6ee3-0175-442c-8e5b-2a30496a194a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInInventories"/>
    <link:calculationArc order="8" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_c38742d0-1622-479b-85dc-ff37285f0733" xlink:to="loc_us-gaap_IncreaseDecreaseInInventories_3e2b6ee3-0175-442c-8e5b-2a30496a194a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryLIFOReservePeriodCharge_09aa057a-1ccf-47eb-93a8-9544d6b1a288" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryLIFOReservePeriodCharge"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_c38742d0-1622-479b-85dc-ff37285f0733" xlink:to="loc_us-gaap_InventoryLIFOReservePeriodCharge_09aa057a-1ccf-47eb-93a8-9544d6b1a288" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseExpense_b8f9cd5a-9528-4464-b4ff-bc53a7c741bb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseExpense"/>
    <link:calculationArc order="10" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_c38742d0-1622-479b-85dc-ff37285f0733" xlink:to="loc_us-gaap_OperatingLeaseExpense_b8f9cd5a-9528-4464-b4ff-bc53a7c741bb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_IncreaseDecreaseInLitigationReserve_0463a6a3-0462-48ee-8f75-ab9979391101" xlink:href="mck-20210331.xsd#mck_IncreaseDecreaseInLitigationReserve"/>
    <link:calculationArc order="11" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_c38742d0-1622-479b-85dc-ff37285f0733" xlink:to="loc_mck_IncreaseDecreaseInLitigationReserve_0463a6a3-0462-48ee-8f75-ab9979391101" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_4ab23b52-8413-4343-afc4-3eb104031a01" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Depreciation"/>
    <link:calculationArc order="12" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_c38742d0-1622-479b-85dc-ff37285f0733" xlink:to="loc_us-gaap_Depreciation_4ab23b52-8413-4343-afc4-3eb104031a01" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfOtherAssets_539fc16c-d247-4680-9eae-66dd2c036996" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GainLossOnSaleOfOtherAssets"/>
    <link:calculationArc order="13" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_c38742d0-1622-479b-85dc-ff37285f0733" xlink:to="loc_us-gaap_GainLossOnSaleOfOtherAssets_539fc16c-d247-4680-9eae-66dd2c036996" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentForAmortization_a4e13d67-5f30-4f98-b293-ae1392c9ab1d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentForAmortization"/>
    <link:calculationArc order="14" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_c38742d0-1622-479b-85dc-ff37285f0733" xlink:to="loc_us-gaap_AdjustmentForAmortization_a4e13d67-5f30-4f98-b293-ae1392c9ab1d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetImpairment_cc6525b5-b813-4997-9664-f870eaaaf8e7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GoodwillAndIntangibleAssetImpairment"/>
    <link:calculationArc order="15" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_c38742d0-1622-479b-85dc-ff37285f0733" xlink:to="loc_us-gaap_GoodwillAndIntangibleAssetImpairment_cc6525b5-b813-4997-9664-f870eaaaf8e7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInDeferredIncomeTaxes_f652dd6a-70c6-47bd-910a-290a001b9aa1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInDeferredIncomeTaxes"/>
    <link:calculationArc order="16" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_c38742d0-1622-479b-85dc-ff37285f0733" xlink:to="loc_us-gaap_IncreaseDecreaseInDeferredIncomeTaxes_f652dd6a-70c6-47bd-910a-290a001b9aa1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccruedTaxesPayable_fe57e248-7146-4b04-a2e2-19c75fd35d3a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInAccruedTaxesPayable"/>
    <link:calculationArc order="17" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_c38742d0-1622-479b-85dc-ff37285f0733" xlink:to="loc_us-gaap_IncreaseDecreaseInAccruedTaxesPayable_fe57e248-7146-4b04-a2e2-19c75fd35d3a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_26e64c79-7412-40ca-90d7-9bc38627091d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_5e9d3f2e-0f7b-4d3a-baeb-19a060c15ae6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_26e64c79-7412-40ca-90d7-9bc38627091d" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_5e9d3f2e-0f7b-4d3a-baeb-19a060c15ae6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashCurrent_c7813f0b-c000-4971-970a-124b34e163fe" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedCashCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_26e64c79-7412-40ca-90d7-9bc38627091d" xlink:to="loc_us-gaap_RestrictedCashCurrent_c7813f0b-c000-4971-970a-124b34e163fe" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_55d8d4c1-22ef-4db0-80bc-b8e469f22fd0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_334abb3e-0802-44fe-86c1-6ba6ede3727a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_55d8d4c1-22ef-4db0-80bc-b8e469f22fd0" xlink:to="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_334abb3e-0802-44fe-86c1-6ba6ede3727a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_c6dddc99-e4a4-4420-aafe-5f235d6e41c3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_55d8d4c1-22ef-4db0-80bc-b8e469f22fd0" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_c6dddc99-e4a4-4420-aafe-5f235d6e41c3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_55db159c-3fa8-4e22-a4bf-49129b9aa4b9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_55d8d4c1-22ef-4db0-80bc-b8e469f22fd0" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_55db159c-3fa8-4e22-a4bf-49129b9aa4b9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_67de064d-3271-43a9-a327-a9955f676256" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_55d8d4c1-22ef-4db0-80bc-b8e469f22fd0" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_67de064d-3271-43a9-a327-a9955f676256" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_d308f1a2-3587-442c-ba3a-6bcd611f0e63" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_52a5d6a2-54bf-480d-ad6c-cd9cedd3ed45" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_d308f1a2-3587-442c-ba3a-6bcd611f0e63" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_52a5d6a2-54bf-480d-ad6c-cd9cedd3ed45" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireSoftware_41f3e2c4-7371-4f9a-b858-f02bdc3c9d1d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsToAcquireSoftware"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_d308f1a2-3587-442c-ba3a-6bcd611f0e63" xlink:to="loc_us-gaap_PaymentsToAcquireSoftware_41f3e2c4-7371-4f9a-b858-f02bdc3c9d1d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_f6755424-2c84-4ace-b9f9-e1a626d55360" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_d308f1a2-3587-442c-ba3a-6bcd611f0e63" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_f6755424-2c84-4ace-b9f9-e1a626d55360" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForProceedsFromOtherInvestingActivities_85d92d54-68b8-4468-9cfd-343d09904876" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsForProceedsFromOtherInvestingActivities"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_d308f1a2-3587-442c-ba3a-6bcd611f0e63" xlink:to="loc_us-gaap_PaymentsForProceedsFromOtherInvestingActivities_85d92d54-68b8-4468-9cfd-343d09904876" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromDivestitureOfInterestInSubsidiariesAndAffiliates_35551d71-7d10-43e4-b7b0-5fdf74d06aca" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromDivestitureOfInterestInSubsidiariesAndAffiliates"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_d308f1a2-3587-442c-ba3a-6bcd611f0e63" xlink:to="loc_us-gaap_ProceedsFromDivestitureOfInterestInSubsidiariesAndAffiliates_35551d71-7d10-43e4-b7b0-5fdf74d06aca" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_6db46990-dfcb-4b67-89fc-e73b5cda771d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromShortTermDebt_df93f2d3-02f0-4280-b782-f8c2ba17df2b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromShortTermDebt"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_6db46990-dfcb-4b67-89fc-e73b5cda771d" xlink:to="loc_us-gaap_ProceedsFromShortTermDebt_df93f2d3-02f0-4280-b782-f8c2ba17df2b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfShortTermDebt_47be3a0c-61c1-4d8a-93c9-0220a8dbfaea" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RepaymentsOfShortTermDebt"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_6db46990-dfcb-4b67-89fc-e73b5cda771d" xlink:to="loc_us-gaap_RepaymentsOfShortTermDebt_47be3a0c-61c1-4d8a-93c9-0220a8dbfaea" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_e2d4519e-8eb7-4cf4-90a7-ad7098e29327" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromIssuanceOfLongTermDebt"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_6db46990-dfcb-4b67-89fc-e73b5cda771d" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_e2d4519e-8eb7-4cf4-90a7-ad7098e29327" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_5729a6b4-7a0c-4a59-a262-179054807654" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RepaymentsOfLongTermDebt"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_6db46990-dfcb-4b67-89fc-e73b5cda771d" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebt_5729a6b4-7a0c-4a59-a262-179054807654" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions_39ff3b31-2218-47ff-ae4c-a6dc0461f6d7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_6db46990-dfcb-4b67-89fc-e73b5cda771d" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions_39ff3b31-2218-47ff-ae4c-a6dc0461f6d7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_e03f4a63-c04b-4027-b29b-5362893d3002" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock"/>
    <link:calculationArc order="6" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_6db46990-dfcb-4b67-89fc-e73b5cda771d" xlink:to="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_e03f4a63-c04b-4027-b29b-5362893d3002" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDividendsCommonStock_a2d97b06-7eaa-4bc9-b137-dd5b88e496cc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsOfDividendsCommonStock"/>
    <link:calculationArc order="7" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_6db46990-dfcb-4b67-89fc-e73b5cda771d" xlink:to="loc_us-gaap_PaymentsOfDividendsCommonStock_a2d97b06-7eaa-4bc9-b137-dd5b88e496cc" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_fd14d985-a858-47c9-9ee5-a08199219100" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromPaymentsForOtherFinancingActivities"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_6db46990-dfcb-4b67-89fc-e73b5cda771d" xlink:to="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_fd14d985-a858-47c9-9ee5-a08199219100" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/SignificantAccountingPolicies" xlink:type="simple" xlink:href="mck-20210331.xsd#SignificantAccountingPolicies"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/SignificantAccountingPolicies" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/SignificantAccountingPoliciesPolicies" xlink:type="simple" xlink:href="mck-20210331.xsd#SignificantAccountingPoliciesPolicies"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/SignificantAccountingPoliciesPolicies" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/SignificantAccountingPoliciesTables" xlink:type="simple" xlink:href="mck-20210331.xsd#SignificantAccountingPoliciesTables"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/SignificantAccountingPoliciesTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/SignificantAccountingPoliciesDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#SignificantAccountingPoliciesDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/SignificantAccountingPoliciesDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/SignificantAccountingPoliciesReceivablesNetDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#SignificantAccountingPoliciesReceivablesNetDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/SignificantAccountingPoliciesReceivablesNetDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivablesNetCurrent_1ddc27af-127b-40be-92cd-837bb0d98d4b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReceivablesNetCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableGrossCurrent_2a7c58c6-6944-431c-be61-12137c66e9c0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsReceivableGrossCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ReceivablesNetCurrent_1ddc27af-127b-40be-92cd-837bb0d98d4b" xlink:to="loc_us-gaap_AccountsReceivableGrossCurrent_2a7c58c6-6944-431c-be61-12137c66e9c0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_e37b1184-7b53-4460-83c3-8c3819932a4f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ReceivablesNetCurrent_1ddc27af-127b-40be-92cd-837bb0d98d4b" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_e37b1184-7b53-4460-83c3-8c3819932a4f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableGrossCurrent_85ac4bb7-ba18-4a00-ba7a-e8e288d2753b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsReceivableGrossCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_AccountsReceivableCustomerAccountsGross_9969a213-b2d2-407b-958a-e79e8cd357f9" xlink:href="mck-20210331.xsd#mck_AccountsReceivableCustomerAccountsGross"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccountsReceivableGrossCurrent_85ac4bb7-ba18-4a00-ba7a-e8e288d2753b" xlink:to="loc_mck_AccountsReceivableCustomerAccountsGross_9969a213-b2d2-407b-958a-e79e8cd357f9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherReceivablesGrossCurrent_8f492fbc-4abc-489f-82f1-b19b78ec032a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherReceivablesGrossCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccountsReceivableGrossCurrent_85ac4bb7-ba18-4a00-ba7a-e8e288d2753b" xlink:to="loc_us-gaap_OtherReceivablesGrossCurrent_8f492fbc-4abc-489f-82f1-b19b78ec032a" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/SignificantAccountingPoliciesPropertyPlantandEquipmentNetDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#SignificantAccountingPoliciesPropertyPlantandEquipmentNetDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/SignificantAccountingPoliciesPropertyPlantandEquipmentNetDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_f092961b-ab37-41d7-8361-f68825442c2a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_124b9a93-8d1e-4819-b85f-dddbcd9b28cf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNet_f092961b-ab37-41d7-8361-f68825442c2a" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_124b9a93-8d1e-4819-b85f-dddbcd9b28cf" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_508b766e-f032-4145-bd30-a695b2bccc12" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNet_f092961b-ab37-41d7-8361-f68825442c2a" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_508b766e-f032-4145-bd30-a695b2bccc12" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_5cdfb678-710c-40e7-9262-baccae98638f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressGross_b3f0511e-a5a2-4e2f-8f25-6dc1ed4e2e3f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConstructionInProgressGross"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentGross_5cdfb678-710c-40e7-9262-baccae98638f" xlink:to="loc_us-gaap_ConstructionInProgressGross_b3f0511e-a5a2-4e2f-8f25-6dc1ed4e2e3f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Land_594d3f7d-630c-4c6b-8f48-94c85ac6e130" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Land"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentGross_5cdfb678-710c-40e7-9262-baccae98638f" xlink:to="loc_us-gaap_Land_594d3f7d-630c-4c6b-8f48-94c85ac6e130" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentOther_d12c43d1-03cd-47c2-aa59-5ffd2621895e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentOther"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentGross_5cdfb678-710c-40e7-9262-baccae98638f" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentOther_d12c43d1-03cd-47c2-aa59-5ffd2621895e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BuildingsAndImprovementsGross_a92f2fb7-df0b-49ea-9d9a-cc921ee57ff0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BuildingsAndImprovementsGross"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentGross_5cdfb678-710c-40e7-9262-baccae98638f" xlink:to="loc_us-gaap_BuildingsAndImprovementsGross_a92f2fb7-df0b-49ea-9d9a-cc921ee57ff0" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/InvestmentinChangeHealthcareJointVenture" xlink:type="simple" xlink:href="mck-20210331.xsd#InvestmentinChangeHealthcareJointVenture"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/InvestmentinChangeHealthcareJointVenture" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/InvestmentinChangeHealthcareJointVentureTables" xlink:type="simple" xlink:href="mck-20210331.xsd#InvestmentinChangeHealthcareJointVentureTables"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/InvestmentinChangeHealthcareJointVentureTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/InvestmentinChangeHealthcareJointVentureDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#InvestmentinChangeHealthcareJointVentureDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/InvestmentinChangeHealthcareJointVentureDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/InvestmentinChangeHealthcareJointVentureNetGainonSplitoffofChangeHealthcareJVDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#InvestmentinChangeHealthcareJointVentureNetGainonSplitoffofChangeHealthcareJVDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/InvestmentinChangeHealthcareJointVentureNetGainonSplitoffofChangeHealthcareJVDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal_2b4b4e97-0a8f-4154-9783-fab49be3a26e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_EquityMethodInvestmentFairValueofStockAccepted_b19b8ff0-1a5f-40bf-bf87-d94e0ba65bed" xlink:href="mck-20210331.xsd#mck_EquityMethodInvestmentFairValueofStockAccepted"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal_2b4b4e97-0a8f-4154-9783-fab49be3a26e" xlink:to="loc_mck_EquityMethodInvestmentFairValueofStockAccepted_b19b8ff0-1a5f-40bf-bf87-d94e0ba65bed" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_EquityMethodInvestmentCarryingAmount_6b7239ed-e0fd-49b3-8ad2-ac63d5bc2ccf" xlink:href="mck-20210331.xsd#mck_EquityMethodInvestmentCarryingAmount"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal_2b4b4e97-0a8f-4154-9783-fab49be3a26e" xlink:to="loc_mck_EquityMethodInvestmentCarryingAmount_6b7239ed-e0fd-49b3-8ad2-ac63d5bc2ccf" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_EquityMethodInvestmentsReversalofDeferredTaxLiability_a903a236-a604-451a-9d40-a5d59c760370" xlink:href="mck-20210331.xsd#mck_EquityMethodInvestmentsReversalofDeferredTaxLiability"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal_2b4b4e97-0a8f-4154-9783-fab49be3a26e" xlink:to="loc_mck_EquityMethodInvestmentsReversalofDeferredTaxLiability_a903a236-a604-451a-9d40-a5d59c760370" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_EquityMethodInvestmentReleaseofAccumulatedOtherComprehensiveincomeLoss_801c17ee-982b-4423-b7d1-78d5e1788320" xlink:href="mck-20210331.xsd#mck_EquityMethodInvestmentReleaseofAccumulatedOtherComprehensiveincomeLoss"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal_2b4b4e97-0a8f-4154-9783-fab49be3a26e" xlink:to="loc_mck_EquityMethodInvestmentReleaseofAccumulatedOtherComprehensiveincomeLoss_801c17ee-982b-4423-b7d1-78d5e1788320" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_EquityMethodInvestmentTransactionCostsIncurred_2f7f5a0c-dbe9-4757-bf14-487906dbd0db" xlink:href="mck-20210331.xsd#mck_EquityMethodInvestmentTransactionCostsIncurred"/>
    <link:calculationArc order="5" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal_2b4b4e97-0a8f-4154-9783-fab49be3a26e" xlink:to="loc_mck_EquityMethodInvestmentTransactionCostsIncurred_2f7f5a0c-dbe9-4757-bf14-487906dbd0db" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/HeldforSale" xlink:type="simple" xlink:href="mck-20210331.xsd#HeldforSale"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/HeldforSale" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/HeldforSaleTables" xlink:type="simple" xlink:href="mck-20210331.xsd#HeldforSaleTables"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/HeldforSaleTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/HeldforSaleNarrativeDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#HeldforSaleNarrativeDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/HeldforSaleNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/HeldforSaleAssetsandLiabilitiesHeldforSaleDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#HeldforSaleAssetsandLiabilitiesHeldforSaleDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/HeldforSaleAssetsandLiabilitiesHeldforSaleDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_c5f9ff7e-47bb-48fa-9b88-d8df9bf2249d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet_36e3f79b-bad8-469e-97e5-2eaa93606744" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_c5f9ff7e-47bb-48fa-9b88-d8df9bf2249d" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet_36e3f79b-bad8-469e-97e5-2eaa93606744" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationInventoryCurrent_0cd8eeec-ab02-4b5c-b3c1-d3fb6df70f56" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationInventoryCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_c5f9ff7e-47bb-48fa-9b88-d8df9bf2249d" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationInventoryCurrent_0cd8eeec-ab02-4b5c-b3c1-d3fb6df70f56" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_DisposalGroupIncludingDiscontinuedOperationReclassifiedLongtermAssetsCurrent_3d3c7d1f-9cb7-449c-b3ad-3c0f84d66ec6" xlink:href="mck-20210331.xsd#mck_DisposalGroupIncludingDiscontinuedOperationReclassifiedLongtermAssetsCurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_c5f9ff7e-47bb-48fa-9b88-d8df9bf2249d" xlink:to="loc_mck_DisposalGroupIncludingDiscontinuedOperationReclassifiedLongtermAssetsCurrent_3d3c7d1f-9cb7-449c-b3ad-3c0f84d66ec6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_DisposalGroupNotDiscontinuedOperationLossGainonWritedown1_79786ce1-fc92-4cb3-87eb-4994cb19e3aa" xlink:href="mck-20210331.xsd#mck_DisposalGroupNotDiscontinuedOperationLossGainonWritedown1"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_c5f9ff7e-47bb-48fa-9b88-d8df9bf2249d" xlink:to="loc_mck_DisposalGroupNotDiscontinuedOperationLossGainonWritedown1_79786ce1-fc92-4cb3-87eb-4994cb19e3aa" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_19985003-2cba-4544-be51-9340a69fc77e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_DisposalGroupIncludingDiscontinuedOperationDraftsandAccountsPayableCurrent_f0de7acb-a31a-42f3-9731-282c03784dcf" xlink:href="mck-20210331.xsd#mck_DisposalGroupIncludingDiscontinuedOperationDraftsandAccountsPayableCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_19985003-2cba-4544-be51-9340a69fc77e" xlink:to="loc_mck_DisposalGroupIncludingDiscontinuedOperationDraftsandAccountsPayableCurrent_f0de7acb-a31a-42f3-9731-282c03784dcf" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_DisposalGroupIncludingDiscontinuedOperationOtherAccruedLiabilitiesCurrent_88b160ca-c304-4d5f-81d0-4e8f990ef4ba" xlink:href="mck-20210331.xsd#mck_DisposalGroupIncludingDiscontinuedOperationOtherAccruedLiabilitiesCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_19985003-2cba-4544-be51-9340a69fc77e" xlink:to="loc_mck_DisposalGroupIncludingDiscontinuedOperationOtherAccruedLiabilitiesCurrent_88b160ca-c304-4d5f-81d0-4e8f990ef4ba" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_DisposalGroupIncludingDiscontinuedOperationReclassifiedLongtermLiabilitiesCurrent_dc322a59-cabd-4cea-957b-16824a6ee9d1" xlink:href="mck-20210331.xsd#mck_DisposalGroupIncludingDiscontinuedOperationReclassifiedLongtermLiabilitiesCurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_19985003-2cba-4544-be51-9340a69fc77e" xlink:to="loc_mck_DisposalGroupIncludingDiscontinuedOperationReclassifiedLongtermLiabilitiesCurrent_dc322a59-cabd-4cea-957b-16824a6ee9d1" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/RestructuringImpairmentandRelatedCharges" xlink:type="simple" xlink:href="mck-20210331.xsd#RestructuringImpairmentandRelatedCharges"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/RestructuringImpairmentandRelatedCharges" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/RestructuringImpairmentandRelatedChargesTables" xlink:type="simple" xlink:href="mck-20210331.xsd#RestructuringImpairmentandRelatedChargesTables"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/RestructuringImpairmentandRelatedChargesTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/RestructuringImpairmentandRelatedChargesNarrativeDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#RestructuringImpairmentandRelatedChargesNarrativeDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/RestructuringImpairmentandRelatedChargesNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/RestructuringImpairmentandRelatedChargesSummaryofDetailsforChargesRecordedDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#RestructuringImpairmentandRelatedChargesSummaryofDetailsforChargesRecordedDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/RestructuringImpairmentandRelatedChargesSummaryofDetailsforChargesRecordedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_794da361-5c13-41a8-ada1-0c77671bf9d6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestructuringCharges"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeveranceCosts1_ca70b435-fd07-48b8-ae07-c2300f106564" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SeveranceCosts1"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_RestructuringCharges_794da361-5c13-41a8-ada1-0c77671bf9d6" xlink:to="loc_us-gaap_SeveranceCosts1_ca70b435-fd07-48b8-ae07-c2300f106564" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessExitCosts1_5accca6c-4797-4236-ab26-06d1e849130c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessExitCosts1"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_RestructuringCharges_794da361-5c13-41a8-ada1-0c77671bf9d6" xlink:to="loc_us-gaap_BusinessExitCosts1_5accca6c-4797-4236-ab26-06d1e849130c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_AssetImpairmentChargesIncludingAcceleratedDepreciation_89a26e2c-a3b9-464c-8e7c-8c01ea38272e" xlink:href="mck-20210331.xsd#mck_AssetImpairmentChargesIncludingAcceleratedDepreciation"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_RestructuringCharges_794da361-5c13-41a8-ada1-0c77671bf9d6" xlink:to="loc_mck_AssetImpairmentChargesIncludingAcceleratedDepreciation_89a26e2c-a3b9-464c-8e7c-8c01ea38272e" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/RestructuringImpairmentandRelatedChargesSummaryofActivityRelatedtoRestructuringLiabilityDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#RestructuringImpairmentandRelatedChargesSummaryofActivityRelatedtoRestructuringLiabilityDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/RestructuringImpairmentandRelatedChargesSummaryofActivityRelatedtoRestructuringLiabilityDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/BusinessAcquisitionsandDivestitures" xlink:type="simple" xlink:href="mck-20210331.xsd#BusinessAcquisitionsandDivestitures"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/BusinessAcquisitionsandDivestitures" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/BusinessAcquisitionsandDivestituresTables" xlink:type="simple" xlink:href="mck-20210331.xsd#BusinessAcquisitionsandDivestituresTables"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/BusinessAcquisitionsandDivestituresTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/BusinessAcquisitionsandDivestituresAcquisitionofMedicalSpecialtiesDistributorsDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#BusinessAcquisitionsandDivestituresAcquisitionofMedicalSpecialtiesDistributorsDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/BusinessAcquisitionsandDivestituresAcquisitionofMedicalSpecialtiesDistributorsDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/BusinessAcquisitionsandDivestituresFairValuesRecognizedofAssetsAcquiredandLiabilitiesAssumedDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#BusinessAcquisitionsandDivestituresFairValuesRecognizedofAssetsAcquiredandLiabilitiesAssumedDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/BusinessAcquisitionsandDivestituresFairValuesRecognizedofAssetsAcquiredandLiabilitiesAssumedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_mck_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedNetofCashandCashEquivalents_be09056a-0ffc-422b-a409-84152772c83d" xlink:href="mck-20210331.xsd#mck_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedNetofCashandCashEquivalents"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_2c0aab96-1eab-4ee2-aff7-546366fdaeb4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedNetofCashandCashEquivalents_be09056a-0ffc-422b-a409-84152772c83d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_2c0aab96-1eab-4ee2-aff7-546366fdaeb4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentAssetsOtherAssetsNetofCashandCashEquivalents_715ac5da-ff83-469e-b920-2b9bfbfae216" xlink:href="mck-20210331.xsd#mck_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentAssetsOtherAssetsNetofCashandCashEquivalents"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedNetofCashandCashEquivalents_be09056a-0ffc-422b-a409-84152772c83d" xlink:to="loc_mck_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentAssetsOtherAssetsNetofCashandCashEquivalents_715ac5da-ff83-469e-b920-2b9bfbfae216" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_b7cee5f5-1073-475b-ab5f-09fa69f85fda" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Goodwill"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedNetofCashandCashEquivalents_be09056a-0ffc-422b-a409-84152772c83d" xlink:to="loc_us-gaap_Goodwill_b7cee5f5-1073-475b-ab5f-09fa69f85fda" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_aa7ba2c0-eb8e-4073-888a-6a7c0c733610" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedNetofCashandCashEquivalents_be09056a-0ffc-422b-a409-84152772c83d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_aa7ba2c0-eb8e-4073-888a-6a7c0c733610" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_7d44a072-bdd8-4866-94db-ccd79f206a87" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedNetofCashandCashEquivalents_be09056a-0ffc-422b-a409-84152772c83d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_7d44a072-bdd8-4866-94db-ccd79f206a87" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities_9aa48d23-261b-42c0-9767-b791a53675db" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities"/>
    <link:calculationArc order="6" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedNetofCashandCashEquivalents_be09056a-0ffc-422b-a409-84152772c83d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities_9aa48d23-261b-42c0-9767-b791a53675db" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_1ef3ad97-1cef-46f0-b58a-c909662d67ba" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther"/>
    <link:calculationArc order="7" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedNetofCashandCashEquivalents_be09056a-0ffc-422b-a409-84152772c83d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_1ef3ad97-1cef-46f0-b58a-c909662d67ba" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/BusinessAcquisitionsandDivestituresAcquisitionofCoverMyMedsDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#BusinessAcquisitionsandDivestituresAcquisitionofCoverMyMedsDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/BusinessAcquisitionsandDivestituresAcquisitionofCoverMyMedsDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/ShareBasedCompensation" xlink:type="simple" xlink:href="mck-20210331.xsd#ShareBasedCompensation"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/ShareBasedCompensation" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/ShareBasedCompensationTables" xlink:type="simple" xlink:href="mck-20210331.xsd#ShareBasedCompensationTables"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/ShareBasedCompensationTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/ShareBasedCompensationNarrativeDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#ShareBasedCompensationNarrativeDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/ShareBasedCompensationNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/ShareBasedCompensationComponentsofShareBasedCompensationExpenseDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#ShareBasedCompensationComponentsofShareBasedCompensationExpenseDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/ShareBasedCompensationComponentsofShareBasedCompensationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_f5015bcd-4ba8-4c2d-b75e-5d1b6c22f3e5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_5d575de2-c4d8-43c2-951a-f04b025055e9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_f5015bcd-4ba8-4c2d-b75e-5d1b6c22f3e5" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_5d575de2-c4d8-43c2-951a-f04b025055e9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_b99fea47-a007-44dd-84c9-88097a80738f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_f5015bcd-4ba8-4c2d-b75e-5d1b6c22f3e5" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_b99fea47-a007-44dd-84c9-88097a80738f" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/ShareBasedCompensationScheduleofWeightedAverageAssumptionsUsedtoEstimateFairValueofRSUsandPSUsDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#ShareBasedCompensationScheduleofWeightedAverageAssumptionsUsedtoEstimateFairValueofRSUsandPSUsDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/ShareBasedCompensationScheduleofWeightedAverageAssumptionsUsedtoEstimateFairValueofRSUsandPSUsDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/ShareBasedCompensationScheduleofRSUsandPSUsAwardActivityDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#ShareBasedCompensationScheduleofRSUsandPSUsAwardActivityDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/ShareBasedCompensationScheduleofRSUsandPSUsAwardActivityDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/ShareBasedCompensationSummaryofDataRelatedtoRSUsandPSUsAwardActivityDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#ShareBasedCompensationSummaryofDataRelatedtoRSUsandPSUsAwardActivityDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/ShareBasedCompensationSummaryofDataRelatedtoRSUsandPSUsAwardActivityDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/ShareBasedCompensationScheduleofAssumptionsforStockOptionsFairValuesDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#ShareBasedCompensationScheduleofAssumptionsforStockOptionsFairValuesDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/ShareBasedCompensationScheduleofAssumptionsforStockOptionsFairValuesDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/ShareBasedCompensationSummaryofOptionsOutstandingDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#ShareBasedCompensationSummaryofOptionsOutstandingDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/ShareBasedCompensationSummaryofOptionsOutstandingDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/ShareBasedCompensationScheduleofStockOptionActivityDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#ShareBasedCompensationScheduleofStockOptionActivityDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/ShareBasedCompensationScheduleofStockOptionActivityDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/ShareBasedCompensationScheduleofDataRelatedtoStockOptionActivityDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#ShareBasedCompensationScheduleofDataRelatedtoStockOptionActivityDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/ShareBasedCompensationScheduleofDataRelatedtoStockOptionActivityDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/OtherIncomeNet" xlink:type="simple" xlink:href="mck-20210331.xsd#OtherIncomeNet"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/OtherIncomeNet" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/OtherIncomeNetTables" xlink:type="simple" xlink:href="mck-20210331.xsd#OtherIncomeNetTables"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/OtherIncomeNetTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/OtherIncomeNetDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#OtherIncomeNetDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/OtherIncomeNetDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_db844806-8a6b-4eac-9b43-040896e7fc39" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanActuarialGainLossImmediateRecognitionAsComponentInNetPeriodicBenefitCostCredit_31d32208-7882-4962-9f47-30aca65a6492" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanActuarialGainLossImmediateRecognitionAsComponentInNetPeriodicBenefitCostCredit"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_db844806-8a6b-4eac-9b43-040896e7fc39" xlink:to="loc_us-gaap_DefinedBenefitPlanActuarialGainLossImmediateRecognitionAsComponentInNetPeriodicBenefitCostCredit_31d32208-7882-4962-9f47-30aca65a6492" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiGainLoss_e85372dd-c94e-40e1-8eee-e083d358ee3f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquitySecuritiesFvNiGainLoss"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_db844806-8a6b-4eac-9b43-040896e7fc39" xlink:to="loc_us-gaap_EquitySecuritiesFvNiGainLoss_e85372dd-c94e-40e1-8eee-e083d358ee3f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal_6b9fdd2d-28bd-4a33-8185-e090442e8d06" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_db844806-8a6b-4eac-9b43-040896e7fc39" xlink:to="loc_us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal_6b9fdd2d-28bd-4a33-8185-e090442e8d06" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_1decd3f4-bbe0-4931-bf2f-c16687c079ba" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_db844806-8a6b-4eac-9b43-040896e7fc39" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_1decd3f4-bbe0-4931-bf2f-c16687c079ba" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromEquityMethodInvestments_e20a17d7-c63a-439a-a8e5-a37ffee14451" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromEquityMethodInvestments"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_db844806-8a6b-4eac-9b43-040896e7fc39" xlink:to="loc_us-gaap_IncomeLossFromEquityMethodInvestments_e20a17d7-c63a-439a-a8e5-a37ffee14451" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeInterest_a4c5ef92-b1f2-4f7c-bb0f-c7cf7d98687b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InvestmentIncomeInterest"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_db844806-8a6b-4eac-9b43-040896e7fc39" xlink:to="loc_us-gaap_InvestmentIncomeInterest_a4c5ef92-b1f2-4f7c-bb0f-c7cf7d98687b" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/IncomeTaxes" xlink:type="simple" xlink:href="mck-20210331.xsd#IncomeTaxes"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/IncomeTaxes" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/IncomeTaxesTables" xlink:type="simple" xlink:href="mck-20210331.xsd#IncomeTaxesTables"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/IncomeTaxesTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/IncomeTaxesScheduleofIncomefromContinuingOperationsBeforeIncomeTaxesDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#IncomeTaxesScheduleofIncomefromContinuingOperationsBeforeIncomeTaxesDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/IncomeTaxesScheduleofIncomefromContinuingOperationsBeforeIncomeTaxesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_29a3090b-0023-41a4-9f26-7276e9b7653f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic_95a19092-125d-45d7-9753-75ec1bace841" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_29a3090b-0023-41a4-9f26-7276e9b7653f" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic_95a19092-125d-45d7-9753-75ec1bace841" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign_953b97c7-bf35-410d-b2c5-9c49b8e8cb88" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_29a3090b-0023-41a4-9f26-7276e9b7653f" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign_953b97c7-bf35-410d-b2c5-9c49b8e8cb88" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/IncomeTaxesComponentsOfProvisionForIncomeTaxesRelatedToContinuingOperationsDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#IncomeTaxesComponentsOfProvisionForIncomeTaxesRelatedToContinuingOperationsDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/IncomeTaxesComponentsOfProvisionForIncomeTaxesRelatedToContinuingOperationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_5de71b00-3edd-42cd-b6af-d783c8099e70" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_52105267-50d4-4d6f-9ee5-349a2cb13aa3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CurrentIncomeTaxExpenseBenefit"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_5de71b00-3edd-42cd-b6af-d783c8099e70" xlink:to="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_52105267-50d4-4d6f-9ee5-349a2cb13aa3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_5a0e6605-fb09-4cf9-b7c7-3d6edb1c9fa2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_5de71b00-3edd-42cd-b6af-d783c8099e70" xlink:to="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_5a0e6605-fb09-4cf9-b7c7-3d6edb1c9fa2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_d2e657e2-55f5-4220-9628-eac7ddb24e11" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CurrentIncomeTaxExpenseBenefit"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentFederalTaxExpenseBenefit_fe4ed446-d50c-4dc0-8b01-718dc8f981bb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CurrentFederalTaxExpenseBenefit"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_d2e657e2-55f5-4220-9628-eac7ddb24e11" xlink:to="loc_us-gaap_CurrentFederalTaxExpenseBenefit_fe4ed446-d50c-4dc0-8b01-718dc8f981bb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentStateAndLocalTaxExpenseBenefit_e80dbc3a-b6ba-42d6-9239-32a2ca157460" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CurrentStateAndLocalTaxExpenseBenefit"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_d2e657e2-55f5-4220-9628-eac7ddb24e11" xlink:to="loc_us-gaap_CurrentStateAndLocalTaxExpenseBenefit_e80dbc3a-b6ba-42d6-9239-32a2ca157460" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentForeignTaxExpenseBenefit_f9734af0-2316-44c1-894e-8ff28d53b4d7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CurrentForeignTaxExpenseBenefit"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_d2e657e2-55f5-4220-9628-eac7ddb24e11" xlink:to="loc_us-gaap_CurrentForeignTaxExpenseBenefit_f9734af0-2316-44c1-894e-8ff28d53b4d7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_89df3b4f-6a65-4a14-b3cd-35b93369d01b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFederalIncomeTaxExpenseBenefit_1057a735-a867-4ebb-bd93-29962315a80f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredFederalIncomeTaxExpenseBenefit"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_89df3b4f-6a65-4a14-b3cd-35b93369d01b" xlink:to="loc_us-gaap_DeferredFederalIncomeTaxExpenseBenefit_1057a735-a867-4ebb-bd93-29962315a80f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_64089f54-9329-4248-8455-130f8daebe40" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_89df3b4f-6a65-4a14-b3cd-35b93369d01b" xlink:to="loc_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_64089f54-9329-4248-8455-130f8daebe40" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredForeignIncomeTaxExpenseBenefit_26d44b5b-6ee6-4996-90a5-b7ee7bf2a4c4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredForeignIncomeTaxExpenseBenefit"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_89df3b4f-6a65-4a14-b3cd-35b93369d01b" xlink:to="loc_us-gaap_DeferredForeignIncomeTaxExpenseBenefit_26d44b5b-6ee6-4996-90a5-b7ee7bf2a4c4" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/IncomeTaxesNarrativeDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#IncomeTaxesNarrativeDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/IncomeTaxesNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/IncomeTaxesReconciliationBetweenEffectiveTaxRateOnIncomeFromContinuingOperationsAndStatutoryTaxRateDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#IncomeTaxesReconciliationBetweenEffectiveTaxRateOnIncomeFromContinuingOperationsAndStatutoryTaxRateDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/IncomeTaxesReconciliationBetweenEffectiveTaxRateOnIncomeFromContinuingOperationsAndStatutoryTaxRateDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_11de7c6e-c76a-4b5c-8a6f-964ddd920480" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_ff766867-a2b7-4827-ba68-ef8e0af51e21" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_11de7c6e-c76a-4b5c-8a6f-964ddd920480" xlink:to="loc_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_ff766867-a2b7-4827-ba68-ef8e0af51e21" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes_b5a0e8a3-1ffe-4abc-ad01-33d6e6d84b96" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_11de7c6e-c76a-4b5c-8a6f-964ddd920480" xlink:to="loc_us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes_b5a0e8a3-1ffe-4abc-ad01-33d6e6d84b96" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential_ef6bda7c-2d80-4022-b77b-382478ba5cf6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_11de7c6e-c76a-4b5c-8a6f-964ddd920480" xlink:to="loc_us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential_ef6bda7c-2d80-4022-b77b-382478ba5cf6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationTaxContingencies_6fa1e5c3-e934-44d3-9999-27b46a5a05b9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxReconciliationTaxContingencies"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_11de7c6e-c76a-4b5c-8a6f-964ddd920480" xlink:to="loc_us-gaap_IncomeTaxReconciliationTaxContingencies_6fa1e5c3-e934-44d3-9999-27b46a5a05b9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpenseImpairmentLosses_89cf6629-06c6-44bf-9c67-e7138fabc6dc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxReconciliationNondeductibleExpenseImpairmentLosses"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_11de7c6e-c76a-4b5c-8a6f-964ddd920480" xlink:to="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpenseImpairmentLosses_89cf6629-06c6-44bf-9c67-e7138fabc6dc" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_EffectiveIncomeTaxRateReconciliationLitigationAndClaims_7b0a7fd0-f18a-48d3-857a-711279eb323b" xlink:href="mck-20210331.xsd#mck_EffectiveIncomeTaxRateReconciliationLitigationAndClaims"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_11de7c6e-c76a-4b5c-8a6f-964ddd920480" xlink:to="loc_mck_EffectiveIncomeTaxRateReconciliationLitigationAndClaims_7b0a7fd0-f18a-48d3-857a-711279eb323b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_EffectiveIncomeTaxRateReconciliationIntellectualPropertyTransferNetTaxBenefit_48a3d570-6ec3-42f2-9689-6165f17eb160" xlink:href="mck-20210331.xsd#mck_EffectiveIncomeTaxRateReconciliationIntellectualPropertyTransferNetTaxBenefit"/>
    <link:calculationArc order="7" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_11de7c6e-c76a-4b5c-8a6f-964ddd920480" xlink:to="loc_mck_EffectiveIncomeTaxRateReconciliationIntellectualPropertyTransferNetTaxBenefit_48a3d570-6ec3-42f2-9689-6165f17eb160" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationDispositionOfBusiness_675a5cc8-27ce-40d0-9a6a-a7ad2d783a89" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxReconciliationDispositionOfBusiness"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_11de7c6e-c76a-4b5c-8a6f-964ddd920480" xlink:to="loc_us-gaap_IncomeTaxReconciliationDispositionOfBusiness_675a5cc8-27ce-40d0-9a6a-a7ad2d783a89" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationChangeInEnactedTaxRate_e912797c-9fbd-4a44-9e97-be0ed0137729" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxReconciliationChangeInEnactedTaxRate"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_11de7c6e-c76a-4b5c-8a6f-964ddd920480" xlink:to="loc_us-gaap_IncomeTaxReconciliationChangeInEnactedTaxRate_e912797c-9fbd-4a44-9e97-be0ed0137729" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_EffectiveIncomeTaxRateReconciliationCapitalLossCarryback_7d2845e8-4ce2-42aa-ab12-0a8ce8568b9a" xlink:href="mck-20210331.xsd#mck_EffectiveIncomeTaxRateReconciliationCapitalLossCarryback"/>
    <link:calculationArc order="10" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_11de7c6e-c76a-4b5c-8a6f-964ddd920480" xlink:to="loc_mck_EffectiveIncomeTaxRateReconciliationCapitalLossCarryback_7d2845e8-4ce2-42aa-ab12-0a8ce8568b9a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationOtherReconcilingItems_843644da-2f26-424a-8af4-3484559d3c0a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxReconciliationOtherReconcilingItems"/>
    <link:calculationArc order="11" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_11de7c6e-c76a-4b5c-8a6f-964ddd920480" xlink:to="loc_us-gaap_IncomeTaxReconciliationOtherReconcilingItems_843644da-2f26-424a-8af4-3484559d3c0a" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/IncomeTaxesComponentsOfDeferredTaxBalancesDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#IncomeTaxesComponentsOfDeferredTaxBalancesDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/IncomeTaxesComponentsOfDeferredTaxBalancesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsGross_eeb36e36-2587-4e39-b0e6-c14149561ec7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsGross"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts_f413be3c-c384-4417-8500-78f9b58a6811" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_eeb36e36-2587-4e39-b0e6-c14149561ec7" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts_f413be3c-c384-4417-8500-78f9b58a6811" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_DeferredTaxAssetLitigationAndClaims_3fbd3c50-8823-4f87-8769-4ff54373a2f6" xlink:href="mck-20210331.xsd#mck_DeferredTaxAssetLitigationAndClaims"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_eeb36e36-2587-4e39-b0e6-c14149561ec7" xlink:to="loc_mck_DeferredTaxAssetLitigationAndClaims_3fbd3c50-8823-4f87-8769-4ff54373a2f6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits_b8da9d20-b860-49d3-b137-a7aa10505435" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_eeb36e36-2587-4e39-b0e6-c14149561ec7" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits_b8da9d20-b860-49d3-b137-a7aa10505435" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxCreditCarryforwards_f9625318-c47a-4c97-bf1c-5e39973e74ee" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsTaxCreditCarryforwards"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_eeb36e36-2587-4e39-b0e6-c14149561ec7" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxCreditCarryforwards_f9625318-c47a-4c97-bf1c-5e39973e74ee" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_DeferredTaxAssetLeaseObligations_d4d02136-09e0-4589-a1ef-01360929153a" xlink:href="mck-20210331.xsd#mck_DeferredTaxAssetLeaseObligations"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_eeb36e36-2587-4e39-b0e6-c14149561ec7" xlink:to="loc_mck_DeferredTaxAssetLeaseObligations_d4d02136-09e0-4589-a1ef-01360929153a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOther_bc55ec1d-f427-43dd-bff4-6a701d0d9109" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsOther"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_eeb36e36-2587-4e39-b0e6-c14149561ec7" xlink:to="loc_us-gaap_DeferredTaxAssetsOther_bc55ec1d-f427-43dd-bff4-6a701d0d9109" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilities_d42ce643-11a7-4867-abe5-b11760eac6ca" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredIncomeTaxLiabilities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesDeferredExpenseCapitalizedInventoryCosts_d90a4a42-1000-4f9b-93fb-56bf0acbcd09" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxLiabilitiesDeferredExpenseCapitalizedInventoryCosts"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredIncomeTaxLiabilities_d42ce643-11a7-4867-abe5-b11760eac6ca" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesDeferredExpenseCapitalizedInventoryCosts_d90a4a42-1000-4f9b-93fb-56bf0acbcd09" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_7600c531-f143-472f-a9ce-8e93742b0377" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredIncomeTaxLiabilities_d42ce643-11a7-4867-abe5-b11760eac6ca" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_7600c531-f143-472f-a9ce-8e93742b0377" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets_80bac8da-db18-43f9-ae98-5dd1bb3db97b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredIncomeTaxLiabilities_d42ce643-11a7-4867-abe5-b11760eac6ca" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets_80bac8da-db18-43f9-ae98-5dd1bb3db97b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesOther_e1eaafca-01f0-416b-8098-685c830724ac" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxLiabilitiesOther"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredIncomeTaxLiabilities_d42ce643-11a7-4867-abe5-b11760eac6ca" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesOther_e1eaafca-01f0-416b-8098-685c830724ac" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_DeferredTaxLiabilitiesLeaseRightofuseAssets_9ad337ea-1853-42f9-895e-8870a760bd68" xlink:href="mck-20210331.xsd#mck_DeferredTaxLiabilitiesLeaseRightofuseAssets"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredIncomeTaxLiabilities_d42ce643-11a7-4867-abe5-b11760eac6ca" xlink:to="loc_mck_DeferredTaxLiabilitiesLeaseRightofuseAssets_9ad337ea-1853-42f9-895e-8870a760bd68" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilities_d0efb074-fd24-4fbb-a8a8-9fa58560a144" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxLiabilities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxAssetsNet_b11fecfb-97f3-4f98-a22f-76d4a82a93d9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredIncomeTaxAssetsNet"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxLiabilities_d0efb074-fd24-4fbb-a8a8-9fa58560a144" xlink:to="loc_us-gaap_DeferredIncomeTaxAssetsNet_b11fecfb-97f3-4f98-a22f-76d4a82a93d9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_d12c350d-e758-429d-b514-9fb9f1d94c32" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxLiabilities_d0efb074-fd24-4fbb-a8a8-9fa58560a144" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_d12c350d-e758-429d-b514-9fb9f1d94c32" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsNet_3fcfdf34-0dbf-426e-9907-cfdb1d2fbca7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsGross_2e45dd6c-a59d-43af-8266-edec0094ee5c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsGross"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsNet_3fcfdf34-0dbf-426e-9907-cfdb1d2fbca7" xlink:to="loc_us-gaap_DeferredTaxAssetsGross_2e45dd6c-a59d-43af-8266-edec0094ee5c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance_b43c94b3-c4a5-4748-9ea7-a4b6338a4375" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsNet_3fcfdf34-0dbf-426e-9907-cfdb1d2fbca7" xlink:to="loc_us-gaap_DeferredTaxAssetsValuationAllowance_b43c94b3-c4a5-4748-9ea7-a4b6338a4375" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/IncomeTaxesGrossUnrecognizedTaxBenefitsDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#IncomeTaxesGrossUnrecognizedTaxBenefitsDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/IncomeTaxesGrossUnrecognizedTaxBenefitsDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/RedeemableNoncontrollingInterestsandNoncontrollingInterests" xlink:type="simple" xlink:href="mck-20210331.xsd#RedeemableNoncontrollingInterestsandNoncontrollingInterests"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/RedeemableNoncontrollingInterestsandNoncontrollingInterests" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/RedeemableNoncontrollingInterestsandNoncontrollingInterestsTables" xlink:type="simple" xlink:href="mck-20210331.xsd#RedeemableNoncontrollingInterestsandNoncontrollingInterestsTables"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/RedeemableNoncontrollingInterestsandNoncontrollingInterestsTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/RedeemableNoncontrollingInterestsandNoncontrollingInterestsNarrativeDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#RedeemableNoncontrollingInterestsandNoncontrollingInterestsNarrativeDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/RedeemableNoncontrollingInterestsandNoncontrollingInterestsNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/RedeemableNoncontrollingInterestsandNoncontrollingInterestsScheduleofChangesinNoncontrollingInterestsandRedeemableNoncontrollingInterestDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#RedeemableNoncontrollingInterestsandNoncontrollingInterestsScheduleofChangesinNoncontrollingInterestsandRedeemableNoncontrollingInterestDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/RedeemableNoncontrollingInterestsandNoncontrollingInterestsScheduleofChangesinNoncontrollingInterestsandRedeemableNoncontrollingInterestDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/EarningsperCommonShare" xlink:type="simple" xlink:href="mck-20210331.xsd#EarningsperCommonShare"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/EarningsperCommonShare" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/EarningsperCommonShareTables" xlink:type="simple" xlink:href="mck-20210331.xsd#EarningsperCommonShareTables"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/EarningsperCommonShareTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/EarningsperCommonShareScheduleofBasicandDilutedEarningsperCommonShareDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#EarningsperCommonShareScheduleofBasicandDilutedEarningsperCommonShareDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/EarningsperCommonShareScheduleofBasicandDilutedEarningsperCommonShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_04f8a3a3-fe16-47c8-82ae-4c9c3ca4b1fc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_1a336de8-4878-4220-acc4-775c32b5f353" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_04f8a3a3-fe16-47c8-82ae-4c9c3ca4b1fc" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_1a336de8-4878-4220-acc4-775c32b5f353" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_1dfc9370-a05c-4b79-8c0b-a0aa2ea54b4e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_04f8a3a3-fe16-47c8-82ae-4c9c3ca4b1fc" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_1dfc9370-a05c-4b79-8c0b-a0aa2ea54b4e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperations_127a75a9-b780-4762-9951-c8046addd3ad" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromContinuingOperations"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_c84f231a-8029-47c1-a93a-a87657a8cccd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperations_127a75a9-b780-4762-9951-c8046addd3ad" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_c84f231a-8029-47c1-a93a-a87657a8cccd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_294312c3-caae-4ec0-b033-1fa3b69ce4d7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperations_127a75a9-b780-4762-9951-c8046addd3ad" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_294312c3-caae-4ec0-b033-1fa3b69ce4d7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_54cbe998-3770-481d-bff0-2a05bca53108" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperations_0992be6f-3d6a-44c3-9ecf-1b3d530e1727" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromContinuingOperations"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_54cbe998-3770-481d-bff0-2a05bca53108" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperations_0992be6f-3d6a-44c3-9ecf-1b3d530e1727" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax_ab5d17e6-7b91-45e1-aeae-791c83eef66f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_54cbe998-3770-481d-bff0-2a05bca53108" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax_ab5d17e6-7b91-45e1-aeae-791c83eef66f" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/EarningsperCommonShareNarrativeDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#EarningsperCommonShareNarrativeDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/EarningsperCommonShareNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/Leases" xlink:type="simple" xlink:href="mck-20210331.xsd#Leases"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/Leases" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/LeasesTables" xlink:type="simple" xlink:href="mck-20210331.xsd#LeasesTables"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/LeasesTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/LeasesNarrativeDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#LeasesNarrativeDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/LeasesNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/LeasesSupplementalbalancesheetinformationDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#LeasesSupplementalbalancesheetinformationDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/LeasesSupplementalbalancesheetinformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiability_f6c42c9a-c6ce-48e2-be09-b28baae778bb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiability"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityCurrent_7ff5d8f3-5955-433d-8c83-518169ed53f9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiability_f6c42c9a-c6ce-48e2-be09-b28baae778bb" xlink:to="loc_us-gaap_FinanceLeaseLiabilityCurrent_7ff5d8f3-5955-433d-8c83-518169ed53f9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityNoncurrent_49ad73f9-6fb7-44f9-b48f-220866a6004d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityNoncurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiability_f6c42c9a-c6ce-48e2-be09-b28baae778bb" xlink:to="loc_us-gaap_FinanceLeaseLiabilityNoncurrent_49ad73f9-6fb7-44f9-b48f-220866a6004d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_64fd6c22-5ebe-4ffa-92ea-eaae36b5cca7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_7046046c-d8c1-4723-a25f-f8d5a004f3e8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingLeaseLiability_64fd6c22-5ebe-4ffa-92ea-eaae36b5cca7" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_7046046c-d8c1-4723-a25f-f8d5a004f3e8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_6f4cf533-5cd8-42ac-98c7-dc76391a9707" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingLeaseLiability_64fd6c22-5ebe-4ffa-92ea-eaae36b5cca7" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_6f4cf533-5cd8-42ac-98c7-dc76391a9707" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/LeasesComponentsofleasecostsDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#LeasesComponentsofleasecostsDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/LeasesComponentsofleasecostsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_mck_FinanceLeaseCost_fa631f7c-7e56-496b-9ef7-7faf40bbd98f" xlink:href="mck-20210331.xsd#mck_FinanceLeaseCost"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAssetAmortization_f75206ec-9e5a-4255-ad8f-b5eeed629eec" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseRightOfUseAssetAmortization"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_FinanceLeaseCost_fa631f7c-7e56-496b-9ef7-7faf40bbd98f" xlink:to="loc_us-gaap_FinanceLeaseRightOfUseAssetAmortization_f75206ec-9e5a-4255-ad8f-b5eeed629eec" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseInterestExpense_ab5499f3-9eaa-4be1-9afa-7ad31d0188bd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseInterestExpense"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_FinanceLeaseCost_fa631f7c-7e56-496b-9ef7-7faf40bbd98f" xlink:to="loc_us-gaap_FinanceLeaseInterestExpense_ab5499f3-9eaa-4be1-9afa-7ad31d0188bd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseCost_83356863-034d-4f24-8796-c9f30597655f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeaseCost"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermLeaseCost_e26cc96b-5fdc-4529-9696-360a5d09c86c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShortTermLeaseCost"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LeaseCost_83356863-034d-4f24-8796-c9f30597655f" xlink:to="loc_us-gaap_ShortTermLeaseCost_e26cc96b-5fdc-4529-9696-360a5d09c86c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseCost_bd350af6-48e9-4de6-bcdc-84a8e0ac8d1f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseCost"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LeaseCost_83356863-034d-4f24-8796-c9f30597655f" xlink:to="loc_us-gaap_OperatingLeaseCost_bd350af6-48e9-4de6-bcdc-84a8e0ac8d1f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_FinanceLeaseCost_27ceae4f-2b4f-4b80-9a3a-e71c7ed46ba3" xlink:href="mck-20210331.xsd#mck_FinanceLeaseCost"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LeaseCost_83356863-034d-4f24-8796-c9f30597655f" xlink:to="loc_mck_FinanceLeaseCost_27ceae4f-2b4f-4b80-9a3a-e71c7ed46ba3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableLeaseCost_2c49747a-0a10-4a6c-a56f-6c9d23bdbe6d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableLeaseCost"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LeaseCost_83356863-034d-4f24-8796-c9f30597655f" xlink:to="loc_us-gaap_VariableLeaseCost_2c49747a-0a10-4a6c-a56f-6c9d23bdbe6d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubleaseIncome_ff0abd64-e1f3-4b77-b82b-eceb6f9094eb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubleaseIncome"/>
    <link:calculationArc order="5" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LeaseCost_83356863-034d-4f24-8796-c9f30597655f" xlink:to="loc_us-gaap_SubleaseIncome_ff0abd64-e1f3-4b77-b82b-eceb6f9094eb" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/LeasesSupplementalcashflowinformationDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#LeasesSupplementalcashflowinformationDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/LeasesSupplementalcashflowinformationDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/LeasesMaturitiesofleaseliabilitiesDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#LeasesMaturitiesofleaseliabilitiesDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/LeasesMaturitiesofleaseliabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_mck_LeaseLiabilityPaymentsDueYearFour_8fbbacb7-bdce-42ba-be08-c20c909690ca" xlink:href="mck-20210331.xsd#mck_LeaseLiabilityPaymentsDueYearFour"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_b80b7b24-7739-471d-ad54-edc20409b706" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityPaymentsDueYearFour_8fbbacb7-bdce-42ba-be08-c20c909690ca" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_b80b7b24-7739-471d-ad54-edc20409b706" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_fa123246-1006-42b5-8389-362675b98fc9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityPaymentsDueYearFour_8fbbacb7-bdce-42ba-be08-c20c909690ca" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_fa123246-1006-42b5-8389-362675b98fc9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_LeaseLiabilityPaymentsDue_ef462f56-9473-42cf-90bd-af26bedbdfd4" xlink:href="mck-20210331.xsd#mck_LeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_LeaseLiabilityPaymentsDueNextTwelveMonths_2ff8849b-a507-4dc5-b64d-53f99b2cb52a" xlink:href="mck-20210331.xsd#mck_LeaseLiabilityPaymentsDueNextTwelveMonths"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityPaymentsDue_ef462f56-9473-42cf-90bd-af26bedbdfd4" xlink:to="loc_mck_LeaseLiabilityPaymentsDueNextTwelveMonths_2ff8849b-a507-4dc5-b64d-53f99b2cb52a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_LeaseLiabilityPaymentsDueYearTwo_7b21d598-b598-4feb-8c06-2656765fbb45" xlink:href="mck-20210331.xsd#mck_LeaseLiabilityPaymentsDueYearTwo"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityPaymentsDue_ef462f56-9473-42cf-90bd-af26bedbdfd4" xlink:to="loc_mck_LeaseLiabilityPaymentsDueYearTwo_7b21d598-b598-4feb-8c06-2656765fbb45" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_LeaseLiabilityPaymentsDueYearThree_93c2c969-f54e-4234-a95e-d75b46feb29a" xlink:href="mck-20210331.xsd#mck_LeaseLiabilityPaymentsDueYearThree"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityPaymentsDue_ef462f56-9473-42cf-90bd-af26bedbdfd4" xlink:to="loc_mck_LeaseLiabilityPaymentsDueYearThree_93c2c969-f54e-4234-a95e-d75b46feb29a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_LeaseLiabilityPaymentsDueYearFour_860957be-c291-4d7c-8d9d-2ec4482bb502" xlink:href="mck-20210331.xsd#mck_LeaseLiabilityPaymentsDueYearFour"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityPaymentsDue_ef462f56-9473-42cf-90bd-af26bedbdfd4" xlink:to="loc_mck_LeaseLiabilityPaymentsDueYearFour_860957be-c291-4d7c-8d9d-2ec4482bb502" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_LeaseLiabilityPaymentsDueYearFive_f496eecc-5104-4562-a36f-cf9231851540" xlink:href="mck-20210331.xsd#mck_LeaseLiabilityPaymentsDueYearFive"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityPaymentsDue_ef462f56-9473-42cf-90bd-af26bedbdfd4" xlink:to="loc_mck_LeaseLiabilityPaymentsDueYearFive_f496eecc-5104-4562-a36f-cf9231851540" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_LeaseLiabilityPaymentsDueAfterYearFive_868f1a00-381e-42fa-8cc2-cc1880d90ef0" xlink:href="mck-20210331.xsd#mck_LeaseLiabilityPaymentsDueAfterYearFive"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityPaymentsDue_ef462f56-9473-42cf-90bd-af26bedbdfd4" xlink:to="loc_mck_LeaseLiabilityPaymentsDueAfterYearFive_868f1a00-381e-42fa-8cc2-cc1880d90ef0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_LeaseLiabilityPaymentsDueYearFive_4c6fa0de-ed3c-49f0-9695-4a0b981f73e4" xlink:href="mck-20210331.xsd#mck_LeaseLiabilityPaymentsDueYearFive"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_220644e6-32d6-4d53-9824-cd47fe8e0d65" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityPaymentsDueYearFive_4c6fa0de-ed3c-49f0-9695-4a0b981f73e4" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_220644e6-32d6-4d53-9824-cd47fe8e0d65" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_f4f9ed00-a29f-43a6-bb80-969224cb741e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityPaymentsDueYearFive_4c6fa0de-ed3c-49f0-9695-4a0b981f73e4" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_f4f9ed00-a29f-43a6-bb80-969224cb741e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_LeaseLiabilityPaymentsDueNextTwelveMonths_96a47460-8b4b-483d-9e78-12dac469352b" xlink:href="mck-20210331.xsd#mck_LeaseLiabilityPaymentsDueNextTwelveMonths"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_f424978c-a0d7-41fb-8b86-9bf4d2e17242" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityPaymentsDueNextTwelveMonths_96a47460-8b4b-483d-9e78-12dac469352b" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_f424978c-a0d7-41fb-8b86-9bf4d2e17242" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths_95b0d9d0-dedd-4251-94ca-371c6e382fc3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityPaymentsDueNextTwelveMonths_96a47460-8b4b-483d-9e78-12dac469352b" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths_95b0d9d0-dedd-4251-94ca-371c6e382fc3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_3c525fb0-889e-4928-8db0-c02dadea7b0c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_c0df8f74-b975-4d70-afd5-b6f04f09c6de" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_3c525fb0-889e-4928-8db0-c02dadea7b0c" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_c0df8f74-b975-4d70-afd5-b6f04f09c6de" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_5d2ef71a-f504-4567-9cae-ec1314c9157d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_3c525fb0-889e-4928-8db0-c02dadea7b0c" xlink:to="loc_us-gaap_OperatingLeaseLiability_5d2ef71a-f504-4567-9cae-ec1314c9157d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_92e34f51-799a-4d7a-ad8e-33a05b95a7a6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount_76a440b3-a18f-4def-b854-76d6113c5505" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_92e34f51-799a-4d7a-ad8e-33a05b95a7a6" xlink:to="loc_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount_76a440b3-a18f-4def-b854-76d6113c5505" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiability_57a21f40-887f-4638-b784-18c2597b7610" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiability"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_92e34f51-799a-4d7a-ad8e-33a05b95a7a6" xlink:to="loc_us-gaap_FinanceLeaseLiability_57a21f40-887f-4638-b784-18c2597b7610" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_LeaseLiabilityPaymentsDueYearTwo_4511bd91-c384-46e5-a4db-d2b9f34fdccc" xlink:href="mck-20210331.xsd#mck_LeaseLiabilityPaymentsDueYearTwo"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_5d93cd7c-4f71-486e-8536-fc6db693af36" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityPaymentsDueYearTwo_4511bd91-c384-46e5-a4db-d2b9f34fdccc" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_5d93cd7c-4f71-486e-8536-fc6db693af36" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_d73b340e-e880-4975-97d1-13ecf1bf9fa5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityPaymentsDueYearTwo_4511bd91-c384-46e5-a4db-d2b9f34fdccc" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_d73b340e-e880-4975-97d1-13ecf1bf9fa5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_LeaseLiabilityPaymentsDueAfterYearFive_2e2ca624-ccf7-4b69-90b5-6f734b54c4e3" xlink:href="mck-20210331.xsd#mck_LeaseLiabilityPaymentsDueAfterYearFive"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_27716a22-3ce4-4f4b-b6df-80ed8be11f3f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityPaymentsDueAfterYearFive_2e2ca624-ccf7-4b69-90b5-6f734b54c4e3" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_27716a22-3ce4-4f4b-b6df-80ed8be11f3f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive_58c5fa97-3715-4458-a283-fa9287efba4a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityPaymentsDueAfterYearFive_2e2ca624-ccf7-4b69-90b5-6f734b54c4e3" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive_58c5fa97-3715-4458-a283-fa9287efba4a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_LeaseLiabilityPaymentsDueYearThree_e1b0aaa4-3eaf-4e0a-96da-0706ea1d419c" xlink:href="mck-20210331.xsd#mck_LeaseLiabilityPaymentsDueYearThree"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_8484bc24-65e9-4cfb-9112-3c1cd88d6b0d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityPaymentsDueYearThree_e1b0aaa4-3eaf-4e0a-96da-0706ea1d419c" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_8484bc24-65e9-4cfb-9112-3c1cd88d6b0d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_7b7393db-f5cb-4a3b-969a-2efaf1e830cb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityPaymentsDueYearThree_e1b0aaa4-3eaf-4e0a-96da-0706ea1d419c" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_7b7393db-f5cb-4a3b-969a-2efaf1e830cb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_LeaseLiabilityUndiscountedExcessAmount_886b9ac6-695a-4d61-ae76-44ce491590ad" xlink:href="mck-20210331.xsd#mck_LeaseLiabilityUndiscountedExcessAmount"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_7a953497-bb8a-48ac-b98a-fb3abc84c025" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityUndiscountedExcessAmount_886b9ac6-695a-4d61-ae76-44ce491590ad" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_7a953497-bb8a-48ac-b98a-fb3abc84c025" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount_fb2873ca-1d48-41bc-a595-ecd733d37a25" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityUndiscountedExcessAmount_886b9ac6-695a-4d61-ae76-44ce491590ad" xlink:to="loc_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount_fb2873ca-1d48-41bc-a595-ecd733d37a25" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_LeaseLiability_94d9c3ba-aa0d-412d-96f5-0166d656b8ec" xlink:href="mck-20210331.xsd#mck_LeaseLiability"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_bf656195-de72-437c-84ca-23cf016a1bfb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiability_94d9c3ba-aa0d-412d-96f5-0166d656b8ec" xlink:to="loc_us-gaap_OperatingLeaseLiability_bf656195-de72-437c-84ca-23cf016a1bfb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiability_a26d91a7-a2da-4c27-aab4-cc31fd12f709" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiability"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiability_94d9c3ba-aa0d-412d-96f5-0166d656b8ec" xlink:to="loc_us-gaap_FinanceLeaseLiability_a26d91a7-a2da-4c27-aab4-cc31fd12f709" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/LeasesMaturitiesofleaseliabilitiesDetails_1" xlink:type="simple" xlink:href="mck-20210331.xsd#LeasesMaturitiesofleaseliabilitiesDetails_1"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/LeasesMaturitiesofleaseliabilitiesDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_mck_LeaseLiabilityPaymentsDue_75ae9232-0335-44c5-bcb3-67b8abf0e95f" xlink:href="mck-20210331.xsd#mck_LeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_5144cb13-64d8-4bf6-81fd-f0676d51ea3e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityPaymentsDue_75ae9232-0335-44c5-bcb3-67b8abf0e95f" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_5144cb13-64d8-4bf6-81fd-f0676d51ea3e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_b6178694-6154-41eb-8383-deb6aeaa223c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDue"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityPaymentsDue_75ae9232-0335-44c5-bcb3-67b8abf0e95f" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_b6178694-6154-41eb-8383-deb6aeaa223c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_a28743f1-0269-4abb-be0e-1bb00103f4a9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths_556f6c1c-a4ee-4ad0-9643-3c0973b87e1f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_a28743f1-0269-4abb-be0e-1bb00103f4a9" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths_556f6c1c-a4ee-4ad0-9643-3c0973b87e1f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_1c1e9ba9-8b07-4dc3-bcd3-60bf9ebebbf9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_a28743f1-0269-4abb-be0e-1bb00103f4a9" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_1c1e9ba9-8b07-4dc3-bcd3-60bf9ebebbf9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_eb6eedb8-fe85-48a9-87e6-450c6c4d96c5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_a28743f1-0269-4abb-be0e-1bb00103f4a9" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_eb6eedb8-fe85-48a9-87e6-450c6c4d96c5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_68dd9987-5cd6-4522-ad8f-985a99418a8a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_a28743f1-0269-4abb-be0e-1bb00103f4a9" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_68dd9987-5cd6-4522-ad8f-985a99418a8a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_cb8fe759-ee15-4b86-ba20-a7e47890da5f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_a28743f1-0269-4abb-be0e-1bb00103f4a9" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_cb8fe759-ee15-4b86-ba20-a7e47890da5f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive_639e20e1-3a06-47b3-ac4d-347dff61b325" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_a28743f1-0269-4abb-be0e-1bb00103f4a9" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive_639e20e1-3a06-47b3-ac4d-347dff61b325" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_363e6bde-5ba6-4a70-909d-b94d1dd3a7f1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_e4f5941a-35ca-45ed-ab40-a12b1348ef3d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_363e6bde-5ba6-4a70-909d-b94d1dd3a7f1" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_e4f5941a-35ca-45ed-ab40-a12b1348ef3d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_fffc5feb-b4ed-4067-9e1b-f788800fcfb4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_363e6bde-5ba6-4a70-909d-b94d1dd3a7f1" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_fffc5feb-b4ed-4067-9e1b-f788800fcfb4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_6a1ad835-6050-4c63-92b3-894d6bb68d81" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_363e6bde-5ba6-4a70-909d-b94d1dd3a7f1" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_6a1ad835-6050-4c63-92b3-894d6bb68d81" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_ab5e0abd-4695-4e2c-b431-24bd7876b9d8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_363e6bde-5ba6-4a70-909d-b94d1dd3a7f1" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_ab5e0abd-4695-4e2c-b431-24bd7876b9d8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_4a2df376-ef35-48cb-b867-24b7d640fbde" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_363e6bde-5ba6-4a70-909d-b94d1dd3a7f1" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_4a2df376-ef35-48cb-b867-24b7d640fbde" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_8460f9dc-8275-4dc5-9d25-fc6e0c53fceb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_363e6bde-5ba6-4a70-909d-b94d1dd3a7f1" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_8460f9dc-8275-4dc5-9d25-fc6e0c53fceb" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/LeasesMaturitiesofleaseliabilitiesDetails_2" xlink:type="simple" xlink:href="mck-20210331.xsd#LeasesMaturitiesofleaseliabilitiesDetails_2"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/LeasesMaturitiesofleaseliabilitiesDetails_2" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_mck_LeaseLiabilityPaymentsDue_e7004e5a-40b2-4e24-8adb-f00e10f07532" xlink:href="mck-20210331.xsd#mck_LeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_LeaseLiabilityUndiscountedExcessAmount_8690f1b1-8e83-4c31-9f10-f9635d37d195" xlink:href="mck-20210331.xsd#mck_LeaseLiabilityUndiscountedExcessAmount"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityPaymentsDue_e7004e5a-40b2-4e24-8adb-f00e10f07532" xlink:to="loc_mck_LeaseLiabilityUndiscountedExcessAmount_8690f1b1-8e83-4c31-9f10-f9635d37d195" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_LeaseLiability_3e5dc51f-da6a-4877-aeb1-d56e304dcdd6" xlink:href="mck-20210331.xsd#mck_LeaseLiability"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mck_LeaseLiabilityPaymentsDue_e7004e5a-40b2-4e24-8adb-f00e10f07532" xlink:to="loc_mck_LeaseLiability_3e5dc51f-da6a-4877-aeb1-d56e304dcdd6" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/GoodwillandIntangibleAssetsNet" xlink:type="simple" xlink:href="mck-20210331.xsd#GoodwillandIntangibleAssetsNet"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/GoodwillandIntangibleAssetsNet" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/GoodwillandIntangibleAssetsNetTables" xlink:type="simple" xlink:href="mck-20210331.xsd#GoodwillandIntangibleAssetsNetTables"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/GoodwillandIntangibleAssetsNetTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/GoodwillandIntangibleAssetsNetScheduleofChangesintheCarryingAmountofGoodwillDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#GoodwillandIntangibleAssetsNetScheduleofChangesintheCarryingAmountofGoodwillDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/GoodwillandIntangibleAssetsNetScheduleofChangesintheCarryingAmountofGoodwillDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/GoodwillandIntangibleAssetsNetGoodwillImpairmentInputsDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#GoodwillandIntangibleAssetsNetGoodwillImpairmentInputsDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/GoodwillandIntangibleAssetsNetGoodwillImpairmentInputsDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/GoodwillandIntangibleAssetsNetGoodwillNarrativeDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#GoodwillandIntangibleAssetsNetGoodwillNarrativeDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/GoodwillandIntangibleAssetsNetGoodwillNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/GoodwillandIntangibleAssetsNetScheduleofInformationRegardingIntangibleAssetsDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#GoodwillandIntangibleAssetsNetScheduleofInformationRegardingIntangibleAssetsDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/GoodwillandIntangibleAssetsNetScheduleofInformationRegardingIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_e80dac3a-78ff-4052-8a96-79d1aed53383" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_c73a0cec-65a4-41cb-b062-cc6fb2fc6b5b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_e80dac3a-78ff-4052-8a96-79d1aed53383" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_c73a0cec-65a4-41cb-b062-cc6fb2fc6b5b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_5dd82f34-8e0c-404d-ae3a-8e946e0bbc4b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_e80dac3a-78ff-4052-8a96-79d1aed53383" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_5dd82f34-8e0c-404d-ae3a-8e946e0bbc4b" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/GoodwillandIntangibleAssetsNetIntangibleAssetsNarrativeDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#GoodwillandIntangibleAssetsNetIntangibleAssetsNarrativeDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/GoodwillandIntangibleAssetsNetIntangibleAssetsNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/DebtandFinancingActivities" xlink:type="simple" xlink:href="mck-20210331.xsd#DebtandFinancingActivities"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/DebtandFinancingActivities" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/DebtandFinancingActivitiesTables" xlink:type="simple" xlink:href="mck-20210331.xsd#DebtandFinancingActivitiesTables"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/DebtandFinancingActivitiesTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/DebtandFinancingActivitiesScheduleofLongTermDebtDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#DebtandFinancingActivitiesScheduleofLongTermDebtDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/DebtandFinancingActivitiesScheduleofLongTermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_a2ed481c-700a-4015-8a6b-6e59257ac52a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebt"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent_083cb8b7-a3e7-4a54-87ad-e76ba0c261bd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_a2ed481c-700a-4015-8a6b-6e59257ac52a" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent_083cb8b7-a3e7-4a54-87ad-e76ba0c261bd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_d8723df5-e40a-4e1f-844d-b5669f1583d0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_a2ed481c-700a-4015-8a6b-6e59257ac52a" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_d8723df5-e40a-4e1f-844d-b5669f1583d0" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/DebtandFinancingActivitiesLongTermDebtDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#DebtandFinancingActivitiesLongTermDebtDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/DebtandFinancingActivitiesLongTermDebtDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/DebtandFinancingActivitiesRevolvingCreditFacilitiesDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#DebtandFinancingActivitiesRevolvingCreditFacilitiesDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/DebtandFinancingActivitiesRevolvingCreditFacilitiesDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/DebtandFinancingActivitiesCommercialPaperDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#DebtandFinancingActivitiesCommercialPaperDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/DebtandFinancingActivitiesCommercialPaperDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/VariableInterestEntities" xlink:type="simple" xlink:href="mck-20210331.xsd#VariableInterestEntities"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/VariableInterestEntities" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/VariableInterestEntitiesDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#VariableInterestEntitiesDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/VariableInterestEntitiesDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/PensionBenefits" xlink:type="simple" xlink:href="mck-20210331.xsd#PensionBenefits"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/PensionBenefits" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/PensionBenefitsTables" xlink:type="simple" xlink:href="mck-20210331.xsd#PensionBenefitsTables"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/PensionBenefitsTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/PensionBenefitsNarrativeDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#PensionBenefitsNarrativeDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/PensionBenefitsNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/PensionBenefitsScheduleofNetPeriodicExpenseforPensionPlansDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#PensionBenefitsScheduleofNetPeriodicExpenseforPensionPlansDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/PensionBenefitsScheduleofNetPeriodicExpenseforPensionPlansDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_097fc77d-a4ab-461c-8efd-e9648e5197b9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_3d6679aa-b29b-49d3-86f3-72957c887e29" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanServiceCost"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_097fc77d-a4ab-461c-8efd-e9648e5197b9" xlink:to="loc_us-gaap_DefinedBenefitPlanServiceCost_3d6679aa-b29b-49d3-86f3-72957c887e29" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_e7e5580f-e4f8-4beb-a9d2-dd83b43674bf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanInterestCost"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_097fc77d-a4ab-461c-8efd-e9648e5197b9" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_e7e5580f-e4f8-4beb-a9d2-dd83b43674bf" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_262f4730-4349-4a63-856e-16772d4d3f71" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_097fc77d-a4ab-461c-8efd-e9648e5197b9" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_262f4730-4349-4a63-856e-16772d4d3f71" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_DefinedBenefitPlanAmortizationofGainsLossesPriorServiceCostCreditandTransitionObligationsAssets_ad8927b3-e943-42f5-9893-70b6d8d475ee" xlink:href="mck-20210331.xsd#mck_DefinedBenefitPlanAmortizationofGainsLossesPriorServiceCostCreditandTransitionObligationsAssets"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_097fc77d-a4ab-461c-8efd-e9648e5197b9" xlink:to="loc_mck_DefinedBenefitPlanAmortizationofGainsLossesPriorServiceCostCreditandTransitionObligationsAssets_ad8927b3-e943-42f5-9893-70b6d8d475ee" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToCurtailments_6e467c8f-2c1b-46a1-8f5d-586c6d8ca809" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToCurtailments"/>
    <link:calculationArc order="5" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_097fc77d-a4ab-461c-8efd-e9648e5197b9" xlink:to="loc_us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToCurtailments_6e467c8f-2c1b-46a1-8f5d-586c6d8ca809" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/PensionBenefitsScheduleofChangesinBenefitObligationsandPlanAssetsDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#PensionBenefitsScheduleofChangesinBenefitObligationsandPlanAssetsDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/PensionBenefitsScheduleofChangesinBenefitObligationsandPlanAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_50352d35-cfe6-4c95-8f9e-8b7a21c86b56" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanFundedStatusOfPlan"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_4dcf62bb-02b7-4264-8230-2b83a24f58b3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitObligation"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_50352d35-cfe6-4c95-8f9e-8b7a21c86b56" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligation_4dcf62bb-02b7-4264-8230-2b83a24f58b3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_8b9168d5-746c-4194-9d39-55bdc2babf61" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_50352d35-cfe6-4c95-8f9e-8b7a21c86b56" xlink:to="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_8b9168d5-746c-4194-9d39-55bdc2babf61" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet_681dba6a-10e3-49ac-be6d-c95d243361e0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities_872959dc-5212-4ee7-b407-cf57e81d1a84" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet_681dba6a-10e3-49ac-be6d-c95d243361e0" xlink:to="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities_872959dc-5212-4ee7-b407-cf57e81d1a84" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent_ccdadbf1-9a6a-4f15-899a-def83eec5bc6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet_681dba6a-10e3-49ac-be6d-c95d243361e0" xlink:to="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent_ccdadbf1-9a6a-4f15-899a-def83eec5bc6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent_b87ab60a-4b13-4aa4-8835-d36cb8a00107" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet_681dba6a-10e3-49ac-be6d-c95d243361e0" xlink:to="loc_us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent_b87ab60a-4b13-4aa4-8835-d36cb8a00107" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/PensionBenefitsScheduleofProjectedBenefitObligationAccumulatedBenefitObligationandFairValueofPlanAssetsforPensionPlansDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#PensionBenefitsScheduleofProjectedBenefitObligationAccumulatedBenefitObligationandFairValueofPlanAssetsforPensionPlansDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/PensionBenefitsScheduleofProjectedBenefitObligationAccumulatedBenefitObligationandFairValueofPlanAssetsforPensionPlansDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/PensionBenefitsScheduleofAmountsRecognizedinAccumulatedOtherComprehensiveIncomeDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#PensionBenefitsScheduleofAmountsRecognizedinAccumulatedOtherComprehensiveIncomeDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/PensionBenefitsScheduleofAmountsRecognizedinAccumulatedOtherComprehensiveIncomeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax_bedf43f5-5c7a-4422-890d-a29505379cd5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax_7bd9b3be-0929-46dd-ba7e-6be8bb327306" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax_bedf43f5-5c7a-4422-890d-a29505379cd5" xlink:to="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax_7bd9b3be-0929-46dd-ba7e-6be8bb327306" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax_e092e69b-658d-4cbf-89fe-ad43cc09ed44" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax_bedf43f5-5c7a-4422-890d-a29505379cd5" xlink:to="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax_e092e69b-658d-4cbf-89fe-ad43cc09ed44" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/PensionBenefitsScheduleofOtherChangesinAccumulatedOtherComprehensiveIncomeDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#PensionBenefitsScheduleofOtherChangesinAccumulatedOtherComprehensiveIncomeDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/PensionBenefitsScheduleofOtherChangesinAccumulatedOtherComprehensiveIncomeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax_f18c2b3d-9892-4efe-836a-984ff44ada31" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax_a4046b1e-9ef0-4a6c-b4ad-fde4b278e25e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax_f18c2b3d-9892-4efe-836a-984ff44ada31" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax_a4046b1e-9ef0-4a6c-b4ad-fde4b278e25e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax_9f27daea-b533-455c-a061-d39d6599de5a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax_f18c2b3d-9892-4efe-836a-984ff44ada31" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax_9f27daea-b533-455c-a061-d39d6599de5a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax_99ee99c4-7a73-4c14-8f38-3d33ee08f588" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax_f18c2b3d-9892-4efe-836a-984ff44ada31" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax_99ee99c4-7a73-4c14-8f38-3d33ee08f588" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_OtherComprehensiveIncomeDefinedBenefitPlansNetTranslationGainLossArisingDuringPeriodBeforeTax_b8d41390-f0a5-46e4-910a-81d48bad3809" xlink:href="mck-20210331.xsd#mck_OtherComprehensiveIncomeDefinedBenefitPlansNetTranslationGainLossArisingDuringPeriodBeforeTax"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax_f18c2b3d-9892-4efe-836a-984ff44ada31" xlink:to="loc_mck_OtherComprehensiveIncomeDefinedBenefitPlansNetTranslationGainLossArisingDuringPeriodBeforeTax_b8d41390-f0a5-46e4-910a-81d48bad3809" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/PensionBenefitsScheduleofWeightedAverageAssumptionsUsedtoEstimateNetPeriodicPensionExpenseandActuarialPresentValueofBenefitObligationsDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#PensionBenefitsScheduleofWeightedAverageAssumptionsUsedtoEstimateNetPeriodicPensionExpenseandActuarialPresentValueofBenefitObligationsDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/PensionBenefitsScheduleofWeightedAverageAssumptionsUsedtoEstimateNetPeriodicPensionExpenseandActuarialPresentValueofBenefitObligationsDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/PensionBenefitsSummaryofPensionPlanAssetsUsingFairValueHierarchybyAssetClassDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#PensionBenefitsSummaryofPensionPlanAssetsUsingFairValueHierarchybyAssetClassDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/PensionBenefitsSummaryofPensionPlanAssetsUsingFairValueHierarchybyAssetClassDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/PensionBenefitsOtherPostretirementBenefitsPlanDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#PensionBenefitsOtherPostretirementBenefitsPlanDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/PensionBenefitsOtherPostretirementBenefitsPlanDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/HedgingActivities" xlink:type="simple" xlink:href="mck-20210331.xsd#HedgingActivities"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/HedgingActivities" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/HedgingActivitiesTables" xlink:type="simple" xlink:href="mck-20210331.xsd#HedgingActivitiesTables"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/HedgingActivitiesTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/HedgingActivitiesNarrativeDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#HedgingActivitiesNarrativeDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/HedgingActivitiesNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/HedgingActivitiesScheduleofInformationRegardingFairValueofDerivativesonaGrossBasisDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#HedgingActivitiesScheduleofInformationRegardingFairValueofDerivativesonaGrossBasisDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/HedgingActivitiesScheduleofInformationRegardingFairValueofDerivativesonaGrossBasisDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/FairValueMeasurements" xlink:type="simple" xlink:href="mck-20210331.xsd#FairValueMeasurements"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/FairValueMeasurements" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/FairValueMeasurementsTables" xlink:type="simple" xlink:href="mck-20210331.xsd#FairValueMeasurementsTables"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/FairValueMeasurementsTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/FairValueMeasurementsNarrativeDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#FairValueMeasurementsNarrativeDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/FairValueMeasurementsNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/FairValueMeasurementsScheduleofCarryingValuesandEstimatedFairValuesofDebtInstrumentsDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#FairValueMeasurementsScheduleofCarryingValuesandEstimatedFairValuesofDebtInstrumentsDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/FairValueMeasurementsScheduleofCarryingValuesandEstimatedFairValuesofDebtInstrumentsDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/FinancialGuaranteesandWarranties" xlink:type="simple" xlink:href="mck-20210331.xsd#FinancialGuaranteesandWarranties"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/FinancialGuaranteesandWarranties" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/FinancialGuaranteesandWarrantiesDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#FinancialGuaranteesandWarrantiesDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/FinancialGuaranteesandWarrantiesDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/CommitmentsandContingentLiabilities" xlink:type="simple" xlink:href="mck-20210331.xsd#CommitmentsandContingentLiabilities"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/CommitmentsandContingentLiabilities" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/CommitmentsandContingentLiabilitiesDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#CommitmentsandContingentLiabilitiesDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/CommitmentsandContingentLiabilitiesDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/StockholdersEquity" xlink:type="simple" xlink:href="mck-20210331.xsd#StockholdersEquity"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/StockholdersEquity" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/StockholdersEquityTables" xlink:type="simple" xlink:href="mck-20210331.xsd#StockholdersEquityTables"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/StockholdersEquityTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/StockholdersEquityNarrativeDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#StockholdersEquityNarrativeDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/StockholdersEquityNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/StockholdersEquityScheduleofShareRepurchasesDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#StockholdersEquityScheduleofShareRepurchasesDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/StockholdersEquityScheduleofShareRepurchasesDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/StockholdersEquityScheduleofOtherComprehensiveIncomeLossNetofTaxDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#StockholdersEquityScheduleofOtherComprehensiveIncomeLossNetofTaxDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/StockholdersEquityScheduleofOtherComprehensiveIncomeLossNetofTaxDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/StockholdersEquityScheduleofChangesinAccumulatedOtherComprehensiveIncomebyComponentDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#StockholdersEquityScheduleofChangesinAccumulatedOtherComprehensiveIncomebyComponentDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/StockholdersEquityScheduleofChangesinAccumulatedOtherComprehensiveIncomebyComponentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_e8285ca9-e8e9-4b38-a65f-161efe19fef1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_dcef9fac-0a80-4579-9bb3-189fcd6179dd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_e8285ca9-e8e9-4b38-a65f-161efe19fef1" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_dcef9fac-0a80-4579-9bb3-189fcd6179dd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_6d1b9bae-45d5-48da-8039-ba50cbdac07d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_e8285ca9-e8e9-4b38-a65f-161efe19fef1" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_6d1b9bae-45d5-48da-8039-ba50cbdac07d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_7549ccc4-89ad-4903-bfeb-a6a8d96eabca" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_816caaa0-9e3c-4bfd-8c8a-9adaadb8b9ee" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_7549ccc4-89ad-4903-bfeb-a6a8d96eabca" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_816caaa0-9e3c-4bfd-8c8a-9adaadb8b9ee" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToNoncontrollingInterest_0dad0a45-38e2-4757-8658-8aa7f63ca2eb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToNoncontrollingInterest"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_7549ccc4-89ad-4903-bfeb-a6a8d96eabca" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToNoncontrollingInterest_0dad0a45-38e2-4757-8658-8aa7f63ca2eb" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/RelatedPartyBalancesandTransactions" xlink:type="simple" xlink:href="mck-20210331.xsd#RelatedPartyBalancesandTransactions"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/RelatedPartyBalancesandTransactions" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/RelatedPartyBalancesandTransactionsDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#RelatedPartyBalancesandTransactionsDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/RelatedPartyBalancesandTransactionsDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/SegmentsofBusiness" xlink:type="simple" xlink:href="mck-20210331.xsd#SegmentsofBusiness"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/SegmentsofBusiness" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/SegmentsofBusinessTables" xlink:type="simple" xlink:href="mck-20210331.xsd#SegmentsofBusinessTables"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/SegmentsofBusinessTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/SegmentsofBusinessNarrativeDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#SegmentsofBusinessNarrativeDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/SegmentsofBusinessNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/SegmentsofBusinessScheduleofSegmentInformationDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#SegmentsofBusinessScheduleofSegmentInformationDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/SegmentsofBusinessScheduleofSegmentInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_35469dba-f9ea-4fa4-a61a-90773f34c94c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_GrossProfitNetofExpensesIncludingOtherIncome_72d80d77-554f-4364-8d0a-a499f61953c0" xlink:href="mck-20210331.xsd#mck_GrossProfitNetofExpensesIncludingOtherIncome"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_35469dba-f9ea-4fa4-a61a-90773f34c94c" xlink:to="loc_mck_GrossProfitNetofExpensesIncludingOtherIncome_72d80d77-554f-4364-8d0a-a499f61953c0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mck_CorporateOperatingExpenseandOtherIncomeNet_9b1a03d4-f523-42f7-910f-2c8a146e3cff" xlink:href="mck-20210331.xsd#mck_CorporateOperatingExpenseandOtherIncomeNet"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_35469dba-f9ea-4fa4-a61a-90773f34c94c" xlink:to="loc_mck_CorporateOperatingExpenseandOtherIncomeNet_9b1a03d4-f523-42f7-910f-2c8a146e3cff" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_10ba20ad-913b-44d3-b283-e3099740288f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestExpense"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_35469dba-f9ea-4fa4-a61a-90773f34c94c" xlink:to="loc_us-gaap_InterestExpense_10ba20ad-913b-44d3-b283-e3099740288f" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://mckesson123.com/role/SegmentsofBusinessSegmentAssetsandPropertyPlantandEquipmentNetbyGeographicalAreaDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#SegmentsofBusinessSegmentAssetsandPropertyPlantandEquipmentNetbyGeographicalAreaDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/SegmentsofBusinessSegmentAssetsandPropertyPlantandEquipmentNetbyGeographicalAreaDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/QuarterlyFinancialInformationUnaudited" xlink:type="simple" xlink:href="mck-20210331.xsd#QuarterlyFinancialInformationUnaudited"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/QuarterlyFinancialInformationUnaudited" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/QuarterlyFinancialInformationUnauditedTables" xlink:type="simple" xlink:href="mck-20210331.xsd#QuarterlyFinancialInformationUnauditedTables"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/QuarterlyFinancialInformationUnauditedTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/QuarterlyFinancialInformationUnauditedScheduleofQuarterlyFinancialInformationDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#QuarterlyFinancialInformationUnauditedScheduleofQuarterlyFinancialInformationDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/QuarterlyFinancialInformationUnauditedScheduleofQuarterlyFinancialInformationDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/SUPPLEMENTARYCONSOLIDATEDFINANCIALSTATEMENTSCHEDULEVALUATIONANDQUALIFYINGACCOUNTS" xlink:type="simple" xlink:href="mck-20210331.xsd#SUPPLEMENTARYCONSOLIDATEDFINANCIALSTATEMENTSCHEDULEVALUATIONANDQUALIFYINGACCOUNTS"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/SUPPLEMENTARYCONSOLIDATEDFINANCIALSTATEMENTSCHEDULEVALUATIONANDQUALIFYINGACCOUNTS" xlink:type="extended"/>
  <link:roleRef roleURI="http://mckesson123.com/role/SUPPLEMENTARYCONSOLIDATEDFINANCIALSTATEMENTSCHEDULEVALUATIONANDQUALIFYINGACCOUNTSDetails" xlink:type="simple" xlink:href="mck-20210331.xsd#SUPPLEMENTARYCONSOLIDATEDFINANCIALSTATEMENTSCHEDULEVALUATIONANDQUALIFYINGACCOUNTSDetails"/>
  <link:calculationLink xlink:role="http://mckesson123.com/role/SUPPLEMENTARYCONSOLIDATEDFINANCIALSTATEMENTSCHEDULEVALUATIONANDQUALIFYINGACCOUNTSDetails" xlink:type="extended"/>
</link:linkbase>
