<?xml version="1.0" encoding="us-ascii"?>
<!-- RRD ActiveDisclosure(SM) XBRL Linkbase Document - http://www.financial.rrd.com/ -->
<!-- Creation Date      : 2016-02-29T19:48:44.9896692+00:00 -->
<!-- Version            : 2.1.0.1 -->
<!-- Package ID         : 0BFE3679E78F2359CB450E8C8B3B2AD0-0000906709-001512 -->
<!-- Copyright (c) 2016 R. R. Donnelley &amp; Sons Company. All Rights Reserved. -->
<linkbase xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <roleRef xlink:type="simple" xlink:href="nktr-20151231.xsd#TemplateLink" roleURI="http://www.nektar.com/20151231/role/TemplateLink" />
  <roleRef roleURI="http://www.nektar.com/20151231/taxonomy/role/StatementConsolidatedBalanceSheets" xlink:href="nktr-20151231.xsd#Role_StatementConsolidatedBalanceSheets" xlink:type="simple" />
  <calculationLink xlink:type="extended" xlink:role="http://www.nektar.com/20151231/taxonomy/role/StatementConsolidatedBalanceSheets">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherAssetsCurrent" xlink:type="locator" xlink:label="us-gaap_OtherAssetsCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue" xlink:type="locator" xlink:label="us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InventoryNet" xlink:type="locator" xlink:label="us-gaap_InventoryNet" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:type="locator" xlink:label="us-gaap_AccountsReceivableNetCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesCurrent" xlink:type="locator" xlink:label="us-gaap_AvailableForSaleSecuritiesCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:type="locator" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherAssetsNoncurrent" xlink:type="locator" xlink:label="us-gaap_OtherAssetsNoncurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_Goodwill" xlink:type="locator" xlink:label="us-gaap_Goodwill" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentNet" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetsCurrent" xlink:type="locator" xlink:label="us-gaap_AssetsCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_Assets" xlink:type="locator" xlink:label="us-gaap_Assets" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherLiabilitiesCurrent" xlink:type="locator" xlink:label="us-gaap_OtherLiabilitiesCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredRevenueCurrent" xlink:type="locator" xlink:label="us-gaap_DeferredRevenueCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CapitalLeaseObligationsCurrent" xlink:type="locator" xlink:label="us-gaap_CapitalLeaseObligationsCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestPayableCurrent" xlink:type="locator" xlink:label="us-gaap_InterestPayableCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherAccruedLiabilitiesCurrent" xlink:type="locator" xlink:label="us-gaap_OtherAccruedLiabilitiesCurrent" />
    <loc xlink:href="nktr-20151231.xsd#nktr_AccruedClinicalTrialExpenses" xlink:type="locator" xlink:label="nktr_AccruedClinicalTrialExpenses" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:type="locator" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:type="locator" xlink:label="us-gaap_AccountsPayableCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent" xlink:type="locator" xlink:label="us-gaap_OtherLiabilitiesNoncurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredRevenueNoncurrent" xlink:type="locator" xlink:label="us-gaap_DeferredRevenueNoncurrent" />
    <loc xlink:href="nktr-20151231.xsd#nktr_LiabilityRelatedToSaleOfPotentialFutureRoyaltiesNonCurrent" xlink:type="locator" xlink:label="nktr_LiabilityRelatedToSaleOfPotentialFutureRoyaltiesNonCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CapitalLeaseObligationsNoncurrent" xlink:type="locator" xlink:label="us-gaap_CapitalLeaseObligationsNoncurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SeniorLongTermNotes" xlink:type="locator" xlink:label="us-gaap_SeniorLongTermNotes" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:type="locator" xlink:label="us-gaap_LiabilitiesCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:type="locator" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:type="locator" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AdditionalPaidInCapitalCommonStock" xlink:type="locator" xlink:label="us-gaap_AdditionalPaidInCapitalCommonStock" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CommonStockValue" xlink:type="locator" xlink:label="us-gaap_CommonStockValue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PreferredStockValue" xlink:type="locator" xlink:label="us-gaap_PreferredStockValue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockholdersEquity" xlink:type="locator" xlink:label="us-gaap_StockholdersEquity" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CommitmentsAndContingencies" xlink:type="locator" xlink:label="us-gaap_CommitmentsAndContingencies" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_Liabilities" xlink:type="locator" xlink:label="us-gaap_Liabilities" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:type="locator" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_Liabilities" order="10010.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_CommitmentsAndContingencies" order="10020.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_StockholdersEquity" order="10030.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquity" xlink:to="us-gaap_PreferredStockValue" order="10040.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquity" xlink:to="us-gaap_CommonStockValue" order="10050.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquity" xlink:to="us-gaap_AdditionalPaidInCapitalCommonStock" order="10060.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquity" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" order="10070.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquity" xlink:to="us-gaap_RetainedEarningsAccumulatedDeficit" order="10080.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Liabilities" xlink:to="us-gaap_LiabilitiesCurrent" order="10090.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Liabilities" xlink:to="us-gaap_SeniorLongTermNotes" order="10100.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Liabilities" xlink:to="us-gaap_CapitalLeaseObligationsNoncurrent" order="10110.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Liabilities" xlink:to="nktr_LiabilityRelatedToSaleOfPotentialFutureRoyaltiesNonCurrent" order="10120.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Liabilities" xlink:to="us-gaap_DeferredRevenueNoncurrent" order="10130.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Liabilities" xlink:to="us-gaap_OtherLiabilitiesNoncurrent" order="10140.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_AccountsPayableCurrent" order="10150.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_EmployeeRelatedLiabilitiesCurrent" order="10160.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="nktr_AccruedClinicalTrialExpenses" order="10170.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_OtherAccruedLiabilitiesCurrent" order="10180.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_InterestPayableCurrent" order="10190.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_CapitalLeaseObligationsCurrent" order="10200.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_DeferredRevenueCurrent" order="10210.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_OtherLiabilitiesCurrent" order="10220.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_AssetsCurrent" order="10230.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_PropertyPlantAndEquipmentNet" order="10240.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_Goodwill" order="10250.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_OtherAssetsNoncurrent" order="10260.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_CashAndCashEquivalentsAtCarryingValue" order="10270.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_AvailableForSaleSecuritiesCurrent" order="10280.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_AccountsReceivableNetCurrent" order="10290.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_InventoryNet" order="10300.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue" order="10310.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_OtherAssetsCurrent" order="10320.00" priority="2" use="optional" weight="1.00" />
  </calculationLink>
  <roleRef roleURI="http://www.nektar.com/20151231/taxonomy/role/StatementConsolidatedStatementsOfOperations" xlink:href="nktr-20151231.xsd#Role_StatementConsolidatedStatementsOfOperations" xlink:type="simple" />
  <calculationLink xlink:type="extended" xlink:role="http://www.nektar.com/20151231/taxonomy/role/StatementConsolidatedStatementsOfOperations">
    <loc xlink:href="nktr-20151231.xsd#nktr_LicenseCollaborationOtherRevenue" xlink:type="locator" xlink:label="nktr_LicenseCollaborationOtherRevenue" />
    <loc xlink:href="nktr-20151231.xsd#nktr_NonCashRoyaltyRevenueRelatedToSaleOfFutureRoyalties" xlink:type="locator" xlink:label="nktr_NonCashRoyaltyRevenueRelatedToSaleOfFutureRoyalties" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RoyaltyRevenue" xlink:type="locator" xlink:label="us-gaap_RoyaltyRevenue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SalesRevenueGoodsNet" xlink:type="locator" xlink:label="us-gaap_SalesRevenueGoodsNet" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GeneralAndAdministrativeExpense" xlink:type="locator" xlink:label="us-gaap_GeneralAndAdministrativeExpense" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense" xlink:type="locator" xlink:label="us-gaap_ResearchAndDevelopmentExpense" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CostOfGoodsSold" xlink:type="locator" xlink:label="us-gaap_CostOfGoodsSold" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CostsAndExpenses" xlink:type="locator" xlink:label="us-gaap_CostsAndExpenses" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_Revenues" xlink:type="locator" xlink:label="us-gaap_Revenues" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpense" xlink:type="locator" xlink:label="us-gaap_OtherNonoperatingIncomeExpense" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:type="locator" xlink:label="us-gaap_GainsLossesOnExtinguishmentOfDebt" />
    <loc xlink:href="nktr-20151231.xsd#nktr_NonCashInterestExpenseRelatedToSaleOfRoyalties" xlink:type="locator" xlink:label="nktr_NonCashInterestExpenseRelatedToSaleOfRoyalties" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestExpense" xlink:type="locator" xlink:label="us-gaap_InterestExpense" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NonoperatingIncomeExpense" xlink:type="locator" xlink:label="us-gaap_NonoperatingIncomeExpense" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:type="locator" xlink:label="us-gaap_OperatingIncomeLoss" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_IncomeTaxExpenseBenefit" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:type="locator" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetIncomeLoss" xlink:type="locator" xlink:label="us-gaap_NetIncomeLoss" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetIncomeLoss" xlink:to="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" order="10010.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetIncomeLoss" xlink:to="us-gaap_IncomeTaxExpenseBenefit" order="10020.00" priority="2" use="optional" weight="-1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_OperatingIncomeLoss" order="10030.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_NonoperatingIncomeExpense" order="10040.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NonoperatingIncomeExpense" xlink:to="us-gaap_InterestExpense" order="10050.00" priority="2" use="optional" weight="-1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NonoperatingIncomeExpense" xlink:to="nktr_NonCashInterestExpenseRelatedToSaleOfRoyalties" order="10060.00" priority="2" use="optional" weight="-1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NonoperatingIncomeExpense" xlink:to="us-gaap_GainsLossesOnExtinguishmentOfDebt" order="10070.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NonoperatingIncomeExpense" xlink:to="us-gaap_OtherNonoperatingIncomeExpense" order="10080.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_Revenues" order="10090.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_CostsAndExpenses" order="10100.00" priority="2" use="optional" weight="-1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CostsAndExpenses" xlink:to="us-gaap_CostOfGoodsSold" order="10110.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CostsAndExpenses" xlink:to="us-gaap_ResearchAndDevelopmentExpense" order="10120.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CostsAndExpenses" xlink:to="us-gaap_GeneralAndAdministrativeExpense" order="10130.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Revenues" xlink:to="us-gaap_SalesRevenueGoodsNet" order="10140.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Revenues" xlink:to="us-gaap_RoyaltyRevenue" order="10150.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Revenues" xlink:to="nktr_NonCashRoyaltyRevenueRelatedToSaleOfFutureRoyalties" order="10160.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Revenues" xlink:to="nktr_LicenseCollaborationOtherRevenue" order="10170.00" priority="2" use="optional" weight="1.00" />
  </calculationLink>
  <roleRef roleURI="http://www.nektar.com/20151231/taxonomy/role/StatementConsolidatedStatementsOfComprehensiveLoss" xlink:href="nktr-20151231.xsd#Role_StatementConsolidatedStatementsOfComprehensiveLoss" xlink:type="simple" />
  <calculationLink xlink:type="extended" xlink:role="http://www.nektar.com/20151231/taxonomy/role/StatementConsolidatedStatementsOfComprehensiveLoss">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax" xlink:type="locator" xlink:label="us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesIncomeTaxExpenseOnChangeInUnrealizedHoldingGainOrLoss" xlink:type="locator" xlink:label="us-gaap_AvailableForSaleSecuritiesIncomeTaxExpenseOnChangeInUnrealizedHoldingGainOrLoss" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesChangeInNetUnrealizedHoldingGainLoss" xlink:type="locator" xlink:label="us-gaap_AvailableForSaleSecuritiesChangeInNetUnrealizedHoldingGainLoss" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:type="locator" xlink:label="us-gaap_OtherComprehensiveIncomeLossNetOfTax" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetIncomeLoss" xlink:type="locator" xlink:label="us-gaap_NetIncomeLoss" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTax" xlink:type="locator" xlink:label="us-gaap_ComprehensiveIncomeNetOfTax" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_ComprehensiveIncomeNetOfTax" xlink:to="us-gaap_NetIncomeLoss" order="10010.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_ComprehensiveIncomeNetOfTax" xlink:to="us-gaap_OtherComprehensiveIncomeLossNetOfTax" order="10020.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:to="us-gaap_AvailableForSaleSecuritiesChangeInNetUnrealizedHoldingGainLoss" order="10030.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:to="us-gaap_AvailableForSaleSecuritiesIncomeTaxExpenseOnChangeInUnrealizedHoldingGainOrLoss" order="10040.00" priority="2" use="optional" weight="-1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:to="us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax" order="10050.00" priority="2" use="optional" weight="1.00" />
  </calculationLink>
  <roleRef roleURI="http://www.nektar.com/20151231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows" xlink:href="nktr-20151231.xsd#Role_StatementConsolidatedStatementsOfCashFlows" xlink:type="simple" />
  <calculationLink xlink:type="extended" xlink:role="http://www.nektar.com/20151231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" />
    <loc xlink:href="nktr-20151231.xsd#nktr_IncreaseDecreaseInMilestonePaymentLiabilities" xlink:type="locator" xlink:label="nktr_IncreaseDecreaseInMilestonePaymentLiabilities" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncreaseDecreaseInDeferredRevenue" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInDeferredRevenue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncreaseDecreaseInInterestPayableNet" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInInterestPayableNet" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncreaseDecreaseInOtherAccruedLiabilities" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInOtherAccruedLiabilities" />
    <loc xlink:href="nktr-20151231.xsd#nktr_IncreaseDecreaseInAccruedClinicalTrialExpenses" xlink:type="locator" xlink:label="nktr_IncreaseDecreaseInAccruedClinicalTrialExpenses" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncreaseDecreaseInEmployeeRelatedLiabilities" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInEmployeeRelatedLiabilities" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayable" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncreaseDecreaseInOtherOperatingAssets" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInOtherOperatingAssets" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncreaseDecreaseInInventories" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInInventories" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInAccountsReceivable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherNoncashIncomeExpense" xlink:type="locator" xlink:label="us-gaap_OtherNoncashIncomeExpense" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_WriteOffOfDeferredDebtIssuanceCost" xlink:type="locator" xlink:label="us-gaap_WriteOffOfDeferredDebtIssuanceCost" />
    <loc xlink:href="nktr-20151231.xsd#nktr_LossFromRedemptionPremiumAndIncrementalInterestOnSecuredDebt" xlink:type="locator" xlink:label="nktr_LossFromRedemptionPremiumAndIncrementalInterestOnSecuredDebt" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DepreciationAndAmortization" xlink:type="locator" xlink:label="us-gaap_DepreciationAndAmortization" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:type="locator" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense" />
    <loc xlink:href="nktr-20151231.xsd#nktr_NonCashInterestExpenseRelatedToSaleOfRoyalties" xlink:type="locator" xlink:label="nktr_NonCashInterestExpenseRelatedToSaleOfRoyalties" />
    <loc xlink:href="nktr-20151231.xsd#nktr_NonCashRoyaltyRevenueRelatedToSaleOfFutureRoyalties" xlink:type="locator" xlink:label="nktr_NonCashRoyaltyRevenueRelatedToSaleOfFutureRoyalties" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetIncomeLoss" xlink:type="locator" xlink:label="us-gaap_NetIncomeLoss" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncreaseDecreaseInRestrictedCash" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInRestrictedCash" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProceedsFromSaleOfAvailableForSaleSecurities" xlink:type="locator" xlink:label="us-gaap_ProceedsFromSaleOfAvailableForSaleSecurities" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities" xlink:type="locator" xlink:label="us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PaymentsToAcquireAvailableForSaleSecurities" xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquireAvailableForSaleSecurities" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlans" xlink:type="locator" xlink:label="us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlans" />
    <loc xlink:href="nktr-20151231.xsd#nktr_ProceedsFromIssuanceOfCommonStockNetOfIssuanceCosts" xlink:type="locator" xlink:label="nktr_ProceedsFromIssuanceOfCommonStockNetOfIssuanceCosts" />
    <loc xlink:href="nktr-20151231.xsd#nktr_RepaymentOfAndProceedsFromSaleOfFutureRoyaltiesNetOfTransactionCosts" xlink:type="locator" xlink:label="nktr_RepaymentOfAndProceedsFromSaleOfFutureRoyaltiesNetOfTransactionCosts" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PaymentsOfDebtExtinguishmentCosts" xlink:type="locator" xlink:label="us-gaap_PaymentsOfDebtExtinguishmentCosts" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RepaymentsOfSeniorDebt" xlink:type="locator" xlink:label="us-gaap_RepaymentsOfSeniorDebt" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProceedsFromIssuanceOfSecuredDebt" xlink:type="locator" xlink:label="us-gaap_ProceedsFromIssuanceOfSecuredDebt" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RepaymentsOfLongTermCapitalLeaseObligations" xlink:type="locator" xlink:label="us-gaap_RepaymentsOfLongTermCapitalLeaseObligations" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents" xlink:type="locator" xlink:label="us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:type="locator" xlink:label="us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:to="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" order="10010.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" order="10020.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:to="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" order="10030.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:to="us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents" order="10040.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_RepaymentsOfLongTermCapitalLeaseObligations" order="10050.00" priority="2" use="optional" weight="-1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_ProceedsFromIssuanceOfSecuredDebt" order="10060.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_RepaymentsOfSeniorDebt" order="10070.00" priority="2" use="optional" weight="-1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_PaymentsOfDebtExtinguishmentCosts" order="10080.00" priority="2" use="optional" weight="-1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="nktr_RepaymentOfAndProceedsFromSaleOfFutureRoyaltiesNetOfTransactionCosts" order="10090.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="nktr_ProceedsFromIssuanceOfCommonStockNetOfIssuanceCosts" order="10100.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlans" order="10110.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:to="us-gaap_PaymentsToAcquireAvailableForSaleSecurities" order="10120.00" priority="2" use="optional" weight="-1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:to="us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities" order="10130.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:to="us-gaap_ProceedsFromSaleOfAvailableForSaleSecurities" order="10140.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:to="us-gaap_IncreaseDecreaseInRestrictedCash" order="10150.00" priority="2" use="optional" weight="-1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:to="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" order="10160.00" priority="2" use="optional" weight="-1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_NetIncomeLoss" order="10170.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="nktr_NonCashRoyaltyRevenueRelatedToSaleOfFutureRoyalties" order="10180.00" priority="2" use="optional" weight="-1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="nktr_NonCashInterestExpenseRelatedToSaleOfRoyalties" order="10190.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_AllocatedShareBasedCompensationExpense" order="10200.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_DepreciationAndAmortization" order="10210.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="nktr_LossFromRedemptionPremiumAndIncrementalInterestOnSecuredDebt" order="10220.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_WriteOffOfDeferredDebtIssuanceCost" order="10230.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_OtherNoncashIncomeExpense" order="10240.00" priority="2" use="optional" weight="-1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_IncreaseDecreaseInAccountsReceivable" order="10250.00" priority="2" use="optional" weight="-1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_IncreaseDecreaseInInventories" order="10260.00" priority="2" use="optional" weight="-1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_IncreaseDecreaseInOtherOperatingAssets" order="10270.00" priority="2" use="optional" weight="-1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_IncreaseDecreaseInAccountsPayable" order="10280.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_IncreaseDecreaseInEmployeeRelatedLiabilities" order="10290.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="nktr_IncreaseDecreaseInAccruedClinicalTrialExpenses" order="10300.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_IncreaseDecreaseInOtherAccruedLiabilities" order="10310.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_IncreaseDecreaseInInterestPayableNet" order="10320.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_IncreaseDecreaseInDeferredRevenue" order="10330.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="nktr_IncreaseDecreaseInMilestonePaymentLiabilities" order="10340.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" order="10350.00" priority="2" use="optional" weight="1.00" />
  </calculationLink>
  <roleRef roleURI="http://www.nektar.com/20151231/taxonomy/role/DisclosureCashAndInvestmentsInMarketableSecuritiesCashAndInvestmentsInMarketableSecuritiesIncludingCashEquivalentsAndRestrictedCashDetail" xlink:href="nktr-20151231.xsd#Role_DisclosureCashAndInvestmentsInMarketableSecuritiesCashAndInvestmentsInMarketableSecuritiesIncludingCashEquivalentsAndRestrictedCashDetail" xlink:type="simple" />
  <calculationLink xlink:type="extended" xlink:role="http://www.nektar.com/20151231/taxonomy/role/DisclosureCashAndInvestmentsInMarketableSecuritiesCashAndInvestmentsInMarketableSecuritiesIncludingCashEquivalentsAndRestrictedCashDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue" xlink:type="locator" xlink:label="us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesCurrent" xlink:type="locator" xlink:label="us-gaap_AvailableForSaleSecuritiesCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:type="locator" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue" />
    <loc xlink:href="nktr-20151231.xsd#nktr_CashRestrictedCashCashEquivalentsAndAvailableForSaleInvestments" xlink:type="locator" xlink:label="nktr_CashRestrictedCashCashEquivalentsAndAvailableForSaleInvestments" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="nktr_CashRestrictedCashCashEquivalentsAndAvailableForSaleInvestments" xlink:to="us-gaap_CashAndCashEquivalentsAtCarryingValue" order="10010.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="nktr_CashRestrictedCashCashEquivalentsAndAvailableForSaleInvestments" xlink:to="us-gaap_AvailableForSaleSecuritiesCurrent" order="10020.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="nktr_CashRestrictedCashCashEquivalentsAndAvailableForSaleInvestments" xlink:to="us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue" order="10030.00" priority="2" use="optional" weight="1.00" />
  </calculationLink>
  <roleRef roleURI="http://www.nektar.com/20151231/taxonomy/role/DisclosureCashAndInvestmentsInMarketableSecuritiesPortfolioOfCashAndInvestmentsInMarketableSecuritiesDetail" xlink:href="nktr-20151231.xsd#Role_DisclosureCashAndInvestmentsInMarketableSecuritiesPortfolioOfCashAndInvestmentsInMarketableSecuritiesDetail" xlink:type="simple" />
  <calculationLink xlink:type="extended" xlink:role="http://www.nektar.com/20151231/taxonomy/role/DisclosureCashAndInvestmentsInMarketableSecuritiesPortfolioOfCashAndInvestmentsInMarketableSecuritiesDetail">
    <loc xlink:href="nktr-20151231.xsd#nktr_CashAndRestrictedCash" xlink:type="locator" xlink:label="nktr_CashAndRestrictedCash" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecurities" xlink:type="locator" xlink:label="us-gaap_AvailableForSaleSecurities" />
    <loc xlink:href="nktr-20151231.xsd#nktr_CashRestrictedCashCashEquivalentsAndAvailableForSaleInvestments" xlink:type="locator" xlink:label="nktr_CashRestrictedCashCashEquivalentsAndAvailableForSaleInvestments" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="nktr_CashRestrictedCashCashEquivalentsAndAvailableForSaleInvestments" xlink:to="us-gaap_AvailableForSaleSecurities" order="10010.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="nktr_CashRestrictedCashCashEquivalentsAndAvailableForSaleInvestments" xlink:to="nktr_CashAndRestrictedCash" order="10020.00" priority="2" use="optional" weight="1.00" />
  </calculationLink>
  <roleRef roleURI="http://www.nektar.com/20151231/taxonomy/role/DisclosureInventoryInventoryDetail" xlink:href="nktr-20151231.xsd#Role_DisclosureInventoryInventoryDetail" xlink:type="simple" />
  <calculationLink xlink:type="extended" xlink:role="http://www.nektar.com/20151231/taxonomy/role/DisclosureInventoryInventoryDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InventoryFinishedGoodsNetOfReserves" xlink:type="locator" xlink:label="us-gaap_InventoryFinishedGoodsNetOfReserves" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InventoryWorkInProcessNetOfReserves" xlink:type="locator" xlink:label="us-gaap_InventoryWorkInProcessNetOfReserves" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InventoryRawMaterialsNetOfReserves" xlink:type="locator" xlink:label="us-gaap_InventoryRawMaterialsNetOfReserves" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InventoryNet" xlink:type="locator" xlink:label="us-gaap_InventoryNet" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InventoryNet" xlink:to="us-gaap_InventoryRawMaterialsNetOfReserves" order="10010.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InventoryNet" xlink:to="us-gaap_InventoryWorkInProcessNetOfReserves" order="10020.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InventoryNet" xlink:to="us-gaap_InventoryFinishedGoodsNetOfReserves" order="10030.00" priority="2" use="optional" weight="1.00" />
  </calculationLink>
  <roleRef roleURI="http://www.nektar.com/20151231/taxonomy/role/DisclosurePropertyPlantAndEquipmentPropertyPlantAndEquipmentDetail" xlink:href="nktr-20151231.xsd#Role_DisclosurePropertyPlantAndEquipmentPropertyPlantAndEquipmentDetail" xlink:type="simple" />
  <calculationLink xlink:type="extended" xlink:role="http://www.nektar.com/20151231/taxonomy/role/DisclosurePropertyPlantAndEquipmentPropertyPlantAndEquipmentDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:type="locator" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" />
    <loc xlink:href="nktr-20151231.xsd#nktr_DepreciablePropertyPlantAndEquipmentGross" xlink:type="locator" xlink:label="nktr_DepreciablePropertyPlantAndEquipmentGross" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConstructionInProgressGross" xlink:type="locator" xlink:label="us-gaap_ConstructionInProgressGross" />
    <loc xlink:href="nktr-20151231.xsd#nktr_DepreciablePropertyPlantAndEquipmentNet" xlink:type="locator" xlink:label="nktr_DepreciablePropertyPlantAndEquipmentNet" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentNet" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_PropertyPlantAndEquipmentNet" xlink:to="nktr_DepreciablePropertyPlantAndEquipmentNet" order="10010.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_PropertyPlantAndEquipmentNet" xlink:to="us-gaap_ConstructionInProgressGross" order="10020.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="nktr_DepreciablePropertyPlantAndEquipmentNet" xlink:to="nktr_DepreciablePropertyPlantAndEquipmentGross" order="10030.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="nktr_DepreciablePropertyPlantAndEquipmentNet" xlink:to="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" order="10040.00" priority="2" use="optional" weight="-1.00" />
  </calculationLink>
  <roleRef roleURI="http://www.nektar.com/20151231/taxonomy/role/DisclosureLeasesFutureMinimumPaymentsForCapitalLeasesDetail" xlink:href="nktr-20151231.xsd#Role_DisclosureLeasesFutureMinimumPaymentsForCapitalLeasesDetail" xlink:type="simple" />
  <calculationLink xlink:type="extended" xlink:role="http://www.nektar.com/20151231/taxonomy/role/DisclosureLeasesFutureMinimumPaymentsForCapitalLeasesDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsDueInThreeYears" xlink:type="locator" xlink:label="us-gaap_CapitalLeasesFutureMinimumPaymentsDueInThreeYears" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsDueInTwoYears" xlink:type="locator" xlink:label="us-gaap_CapitalLeasesFutureMinimumPaymentsDueInTwoYears" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsDueCurrent" xlink:type="locator" xlink:label="us-gaap_CapitalLeasesFutureMinimumPaymentsDueCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsInterestIncludedInPayments" xlink:type="locator" xlink:label="us-gaap_CapitalLeasesFutureMinimumPaymentsInterestIncludedInPayments" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsDue" xlink:type="locator" xlink:label="us-gaap_CapitalLeasesFutureMinimumPaymentsDue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsPresentValueOfNetMinimumPayments" xlink:type="locator" xlink:label="us-gaap_CapitalLeasesFutureMinimumPaymentsPresentValueOfNetMinimumPayments" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CapitalLeasesFutureMinimumPaymentsPresentValueOfNetMinimumPayments" xlink:to="us-gaap_CapitalLeasesFutureMinimumPaymentsDue" order="10010.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CapitalLeasesFutureMinimumPaymentsPresentValueOfNetMinimumPayments" xlink:to="us-gaap_CapitalLeasesFutureMinimumPaymentsInterestIncludedInPayments" order="10020.00" priority="2" use="optional" weight="-1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CapitalLeasesFutureMinimumPaymentsDue" xlink:to="us-gaap_CapitalLeasesFutureMinimumPaymentsDueCurrent" order="10030.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CapitalLeasesFutureMinimumPaymentsDue" xlink:to="us-gaap_CapitalLeasesFutureMinimumPaymentsDueInTwoYears" order="10040.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CapitalLeasesFutureMinimumPaymentsDue" xlink:to="us-gaap_CapitalLeasesFutureMinimumPaymentsDueInThreeYears" order="10050.00" priority="2" use="optional" weight="1.00" />
  </calculationLink>
  <roleRef roleURI="http://www.nektar.com/20151231/taxonomy/role/DisclosureLeasesFutureMinimumPaymentsForCapitalLeasesDetail2" xlink:href="nktr-20151231.xsd#Role_DisclosureLeasesFutureMinimumPaymentsForCapitalLeasesDetail2" xlink:type="simple" />
  <calculationLink xlink:type="extended" xlink:role="http://www.nektar.com/20151231/taxonomy/role/DisclosureLeasesFutureMinimumPaymentsForCapitalLeasesDetail2">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CapitalLeaseObligationsNoncurrent" xlink:type="locator" xlink:label="us-gaap_CapitalLeaseObligationsNoncurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CapitalLeaseObligationsCurrent" xlink:type="locator" xlink:label="us-gaap_CapitalLeaseObligationsCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsPresentValueOfNetMinimumPayments" xlink:type="locator" xlink:label="us-gaap_CapitalLeasesFutureMinimumPaymentsPresentValueOfNetMinimumPayments" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CapitalLeasesFutureMinimumPaymentsPresentValueOfNetMinimumPayments" xlink:to="us-gaap_CapitalLeaseObligationsCurrent" order="10010.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CapitalLeasesFutureMinimumPaymentsPresentValueOfNetMinimumPayments" xlink:to="us-gaap_CapitalLeaseObligationsNoncurrent" order="10020.00" priority="2" use="optional" weight="1.00" />
  </calculationLink>
  <roleRef roleURI="http://www.nektar.com/20151231/taxonomy/role/DisclosureLeasesFutureMinimumLeasePaymentsForOperatingLeasesDetail" xlink:href="nktr-20151231.xsd#Role_DisclosureLeasesFutureMinimumLeasePaymentsForOperatingLeasesDetail" xlink:type="simple" />
  <calculationLink xlink:type="extended" xlink:role="http://www.nektar.com/20151231/taxonomy/role/DisclosureLeasesFutureMinimumLeasePaymentsForOperatingLeasesDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears" xlink:type="locator" xlink:label="us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears" xlink:type="locator" xlink:label="us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears" xlink:type="locator" xlink:label="us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears" xlink:type="locator" xlink:label="us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent" xlink:type="locator" xlink:label="us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDue" xlink:type="locator" xlink:label="us-gaap_OperatingLeasesFutureMinimumPaymentsDue" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingLeasesFutureMinimumPaymentsDue" xlink:to="us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent" order="10010.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingLeasesFutureMinimumPaymentsDue" xlink:to="us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears" order="10020.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingLeasesFutureMinimumPaymentsDue" xlink:to="us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears" order="10030.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingLeasesFutureMinimumPaymentsDue" xlink:to="us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears" order="10040.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingLeasesFutureMinimumPaymentsDue" xlink:to="us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears" order="10050.00" priority="2" use="optional" weight="1.00" />
  </calculationLink>
  <roleRef roleURI="http://www.nektar.com/20151231/taxonomy/role/DisclosureIncomeTaxesLossBeforeProvisionBenefitForIncomeTaxesDetail" xlink:href="nktr-20151231.xsd#Role_DisclosureIncomeTaxesLossBeforeProvisionBenefitForIncomeTaxesDetail" xlink:type="simple" />
  <calculationLink xlink:type="extended" xlink:role="http://www.nektar.com/20151231/taxonomy/role/DisclosureIncomeTaxesLossBeforeProvisionBenefitForIncomeTaxesDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign" xlink:type="locator" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic" xlink:type="locator" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:type="locator" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic" order="10010.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign" order="10020.00" priority="2" use="optional" weight="1.00" />
  </calculationLink>
  <roleRef roleURI="http://www.nektar.com/20151231/taxonomy/role/DisclosureIncomeTaxesProvisionBenefitForIncomeTaxesDetail" xlink:href="nktr-20151231.xsd#Role_DisclosureIncomeTaxesProvisionBenefitForIncomeTaxesDetail" xlink:type="simple" />
  <calculationLink xlink:type="extended" xlink:role="http://www.nektar.com/20151231/taxonomy/role/DisclosureIncomeTaxesProvisionBenefitForIncomeTaxesDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CurrentForeignTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_CurrentForeignTaxExpenseBenefit" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CurrentStateAndLocalTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_CurrentStateAndLocalTaxExpenseBenefit" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CurrentFederalTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_CurrentFederalTaxExpenseBenefit" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredForeignIncomeTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_DeferredForeignIncomeTaxExpenseBenefit" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_DeferredFederalIncomeTaxExpenseBenefit" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefit" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CurrentIncomeTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_CurrentIncomeTaxExpenseBenefit" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_IncomeTaxExpenseBenefit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="us-gaap_CurrentIncomeTaxExpenseBenefit" order="10010.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="us-gaap_DeferredIncomeTaxExpenseBenefit" order="10020.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:to="us-gaap_DeferredFederalIncomeTaxExpenseBenefit" order="10030.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:to="us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit" order="10040.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:to="us-gaap_DeferredForeignIncomeTaxExpenseBenefit" order="10050.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CurrentIncomeTaxExpenseBenefit" xlink:to="us-gaap_CurrentFederalTaxExpenseBenefit" order="10060.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CurrentIncomeTaxExpenseBenefit" xlink:to="us-gaap_CurrentStateAndLocalTaxExpenseBenefit" order="10070.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CurrentIncomeTaxExpenseBenefit" xlink:to="us-gaap_CurrentForeignTaxExpenseBenefit" order="10080.00" priority="2" use="optional" weight="1.00" />
  </calculationLink>
  <roleRef roleURI="http://www.nektar.com/20151231/taxonomy/role/DisclosureIncomeTaxesIncomeTaxProvisionRelatedToContinuingOperationsDetail" xlink:href="nktr-20151231.xsd#Role_DisclosureIncomeTaxesIncomeTaxProvisionRelatedToContinuingOperationsDetail" xlink:type="simple" />
  <calculationLink xlink:type="extended" xlink:role="http://www.nektar.com/20151231/taxonomy/role/DisclosureIncomeTaxesIncomeTaxProvisionRelatedToContinuingOperationsDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeTaxReconciliationOtherAdjustments" xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationOtherAdjustments" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeTaxReconciliationTaxCreditsResearch" xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationTaxCreditsResearch" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential" xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeTaxReconciliationTaxSettlementsForeign" xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationTaxSettlementsForeign" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost" xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost" />
    <loc xlink:href="nktr-20151231.xsd#nktr_IncomeTaxReconciliationNonDeductibleExpenseForLiabilityRelatedSaleOfFutureRoyalties" xlink:type="locator" xlink:label="nktr_IncomeTaxReconciliationNonDeductibleExpenseForLiabilityRelatedSaleOfFutureRoyalties" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_IncomeTaxExpenseBenefit" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" order="10010.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" order="10020.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance" order="10030.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="nktr_IncomeTaxReconciliationNonDeductibleExpenseForLiabilityRelatedSaleOfFutureRoyalties" order="10040.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost" order="10050.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="us-gaap_IncomeTaxReconciliationTaxSettlementsForeign" order="10060.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential" order="10070.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="us-gaap_IncomeTaxReconciliationTaxCreditsResearch" order="10080.00" priority="2" use="optional" weight="-1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="us-gaap_IncomeTaxReconciliationOtherAdjustments" order="10090.00" priority="2" use="optional" weight="1.00" />
  </calculationLink>
  <roleRef roleURI="http://www.nektar.com/20151231/taxonomy/role/DisclosureIncomeTaxesSignificantComponentsOfDeferredTaxAssetsAndLiabilitiesDetail" xlink:href="nktr-20151231.xsd#Role_DisclosureIncomeTaxesSignificantComponentsOfDeferredTaxAssetsAndLiabilitiesDetail" xlink:type="simple" />
  <calculationLink xlink:type="extended" xlink:role="http://www.nektar.com/20151231/taxonomy/role/DisclosureIncomeTaxesSignificantComponentsOfDeferredTaxAssetsAndLiabilitiesDetail">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsOther" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsOther" />
    <loc xlink:href="nktr-20151231.xsd#nktr_DeferredTaxAssetsDepreciationPropertyAndEquipment" xlink:type="locator" xlink:label="nktr_DeferredTaxAssetsDepreciationPropertyAndEquipment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals" />
    <loc xlink:href="nktr-20151231.xsd#nktr_DeferredTaxAssetsFromSaleOfFutureRoyalties" xlink:type="locator" xlink:label="nktr_DeferredTaxAssetsFromSaleOfFutureRoyalties" />
    <loc xlink:href="nktr-20151231.xsd#nktr_DeferredTaxAssetsCapitalizedResearchExpenses" xlink:type="locator" xlink:label="nktr_DeferredTaxAssetsCapitalizedResearchExpenses" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsDeferredIncome" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsDeferredIncome" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsValuationAllowance" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsGross" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsGross" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxLiabilities" xlink:type="locator" xlink:label="us-gaap_DeferredTaxLiabilities" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsNet" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsNet" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxAssetsLiabilitiesNet" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsLiabilitiesNet" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DeferredTaxAssetsLiabilitiesNet" xlink:to="us-gaap_DeferredTaxAssetsNet" order="10010.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DeferredTaxAssetsLiabilitiesNet" xlink:to="us-gaap_DeferredTaxLiabilities" order="10020.00" priority="2" use="optional" weight="-1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DeferredTaxAssetsNet" xlink:to="us-gaap_DeferredTaxAssetsGross" order="10030.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DeferredTaxAssetsNet" xlink:to="us-gaap_DeferredTaxAssetsValuationAllowance" order="10040.00" priority="2" use="optional" weight="-1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DeferredTaxAssetsGross" xlink:to="us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" order="10050.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DeferredTaxAssetsGross" xlink:to="us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch" order="10060.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DeferredTaxAssetsGross" xlink:to="us-gaap_DeferredTaxAssetsDeferredIncome" order="10070.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DeferredTaxAssetsGross" xlink:to="us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost" order="10080.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DeferredTaxAssetsGross" xlink:to="nktr_DeferredTaxAssetsCapitalizedResearchExpenses" order="10090.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DeferredTaxAssetsGross" xlink:to="nktr_DeferredTaxAssetsFromSaleOfFutureRoyalties" order="10100.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DeferredTaxAssetsGross" xlink:to="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals" order="10110.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DeferredTaxAssetsGross" xlink:to="nktr_DeferredTaxAssetsDepreciationPropertyAndEquipment" order="10120.00" priority="2" use="optional" weight="1.00" />
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DeferredTaxAssetsGross" xlink:to="us-gaap_DeferredTaxAssetsOther" order="10130.00" priority="2" use="optional" weight="1.00" />
  </calculationLink>
</linkbase>
