<SEC-DOCUMENT>0001039399-22-000031.txt : 20220517
<SEC-HEADER>0001039399-22-000031.hdr.sgml : 20220517
<ACCEPTANCE-DATETIME>20220517190641
ACCESSION NUMBER:		0001039399-22-000031
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20220514
FILED AS OF DATE:		20220517
DATE AS OF CHANGE:		20220517

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			STEVEN-WAISS KELLEY
		CENTRAL INDEX KEY:			0001498143

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-50307
		FILM NUMBER:		22936474

	MAIL ADDRESS:	
		STREET 1:		7005 SOUTHFRONT ROAD
		CITY:			LIVERMORE
		STATE:			CA
		ZIP:			94551

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			FORMFACTOR INC
		CENTRAL INDEX KEY:			0001039399
		STANDARD INDUSTRIAL CLASSIFICATION:	SEMICONDUCTORS & RELATED DEVICES [3674]
		IRS NUMBER:				133711155
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		7005 SOUTHFRONT ROAD
		CITY:			LIVERMORE
		STATE:			CA
		ZIP:			94551
		BUSINESS PHONE:		9252904000

	MAIL ADDRESS:	
		STREET 1:		7005 SOUTHFRONT ROAD
		CITY:			LIVERMORE
		STATE:			CA
		ZIP:			94551
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_165282877196924.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2022-05-14</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001039399</issuerCik>
        <issuerName>FORMFACTOR INC</issuerName>
        <issuerTradingSymbol>FORM</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001498143</rptOwnerCik>
            <rptOwnerName>STEVEN-WAISS KELLEY</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>FORMFACTOR, INC</rptOwnerStreet1>
            <rptOwnerStreet2>7005 SOUTHFRONT ROAD</rptOwnerStreet2>
            <rptOwnerCity>LIVERMORE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94577</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2022-05-14</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>3792</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>25780</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.0</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2022-05-14</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>3792</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3792.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Restricted Stock Units Vest and become exercisable on May 14, 2022. Settlements of vested units into common stock will occur on the earlier of May 14, 2022 or the date the reporting person ceases to provide service to the Issuer, and thereafter on the first market trading day if the applicable date is not a market trading day.</footnote>
        <footnote id="F2">If the reporting person ceases to provide services to the Issuer for any reason, all Restricted Stock Units that have not yet vested shall be forfeited without consideration except as provided in our Equity Grant Policy for Outside Directors and any other agreements between the reporting person and Issuer, regarding award vesting and exercisability.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Stan Finkelstein, Attorney-in-fact for: Kelley Steven-Waiss</signatureName>
        <signatureDate>2022-05-17</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
