<SEC-DOCUMENT>0001699136-21-000018.txt : 20210209
<SEC-HEADER>0001699136-21-000018.hdr.sgml : 20210209
<ACCEPTANCE-DATETIME>20210209182720
ACCESSION NUMBER:		0001699136-21-000018
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20210207
FILED AS OF DATE:		20210209
DATE AS OF CHANGE:		20210209

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Rosenthal Gary L
		CENTRAL INDEX KEY:			0001198825

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-38390
		FILM NUMBER:		21608367

	MAIL ADDRESS:	
		STREET 1:		333 CLAY STREET
		STREET 2:		SUITE 4620
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77002

	FORMER NAME:	
		FORMER CONFORMED NAME:	ROSENTHAL GARY L
		DATE OF NAME CHANGE:	20021016

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Cactus, Inc.
		CENTRAL INDEX KEY:			0001699136
		STANDARD INDUSTRIAL CLASSIFICATION:	OIL & GAS FILED MACHINERY & EQUIPMENT [3533]
		IRS NUMBER:				352586106
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		920 MEMORIAL CITY WAY
		STREET 2:		SUITE 300
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77024
		BUSINESS PHONE:		713-626-8800

	MAIL ADDRESS:	
		STREET 1:		920 MEMORIAL CITY WAY
		STREET 2:		SUITE 300
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77024
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_161291320862561.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2021-02-07</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001699136</issuerCik>
        <issuerName>Cactus, Inc.</issuerName>
        <issuerTradingSymbol>WHD</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001198825</rptOwnerCik>
            <rptOwnerName>Rosenthal Gary L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>920 MEMORIAL CITY WAY</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 300</rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77024</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>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2021-02-07</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>21930</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>39772</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2021-02-07</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>21930</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>21930.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>7321</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Restricted stock units represent a contingent right to receive Class A common stock. Upon vesting, one share of Class A common stock will be delivered for each vested restricted stock unit.</footnote>
        <footnote id="F2">On February 7, 2018, the reporting person was granted a total of 71,054 restricted stock units, 5,264 of which vested on the first anniversary of the grant date and 65,790 of which vest in three equal annual installments beginning on the first anniversary of the grant date.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Gary Rosenthal, by David Isaac as Attorney-in-fact</signatureName>
        <signatureDate>2021-02-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
