<SEC-DOCUMENT>0000091142-21-000060.txt : 20210415
<SEC-HEADER>0000091142-21-000060.hdr.sgml : 20210415
<ACCEPTANCE-DATETIME>20210415150945
ACCESSION NUMBER:		0000091142-21-000060
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20210413
FILED AS OF DATE:		20210415
DATE AS OF CHANGE:		20210415

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			BROWN RONALD D
		CENTRAL INDEX KEY:			0001206562

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-00475
		FILM NUMBER:		21828311

	MAIL ADDRESS:	
		STREET 1:		2090 FLORENCE AVENUE
		CITY:			CINCINNATI
		STATE:			OH
		ZIP:			45206

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			SMITH A O CORP
		CENTRAL INDEX KEY:			0000091142
		STANDARD INDUSTRIAL CLASSIFICATION:	HOUSEHOLD APPLIANCES [3630]
		IRS NUMBER:				390619790
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		11270 WEST PARK PLACE
		CITY:			MILWAUKEE
		STATE:			WI
		ZIP:			53224
		BUSINESS PHONE:		4143594000

	MAIL ADDRESS:	
		STREET 1:		11270 WEST PARK PLACE
		CITY:			MILWAUKEE
		STATE:			WI
		ZIP:			53224
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2021-04-13</periodOfReport>

    <issuer>
        <issuerCik>0000091142</issuerCik>
        <issuerName>SMITH A O CORP</issuerName>
        <issuerTradingSymbol>AOS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001206562</rptOwnerCik>
            <rptOwnerName>BROWN RONALD D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>A. O. SMITH CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>11270 WEST PARK PLACE</rptOwnerStreet2>
            <rptOwnerCity>MILWAUKEE</rptOwnerCity>
            <rptOwnerState>WI</rptOwnerState>
            <rptOwnerZipCode>53224</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>67.665</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2021-04-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1922</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1922</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>62319</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Payment of retainer in Restricted Stock Units under the A. O. Smith Nonqualified Deferred Compensation Plan based on the average of the high and the low price of Common Stock on April 13, 2021.</footnote>
        <footnote id="F2">The Plan permits the participant to defer the receipt of the award, and Mr. Brown has made a deferral.</footnote>
        <footnote id="F3">The Restricted Stock Units receive a quarterly dividend pursuant to a dividend reinvestment feature of the A. O. Smith Nonqualified Deferred Compensation Plan.  The total amount of dividends received was 1,156 units of Restricted Stock Units.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>James F. Stern, Attorney-in-Fact for Ronald D. Brown</signatureName>
        <signatureDate>2021-04-15</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
