<SEC-DOCUMENT>0001309108-17-000024.txt : 20170308
<SEC-HEADER>0001309108-17-000024.hdr.sgml : 20170308
<ACCEPTANCE-DATETIME>20170308160800
ACCESSION NUMBER:		0001309108-17-000024
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20170306
FILED AS OF DATE:		20170308
DATE AS OF CHANGE:		20170308

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			WEX Inc.
		CENTRAL INDEX KEY:			0001309108
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-BUSINESS SERVICES, NEC [7389]
		IRS NUMBER:				010526993
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		97 DARLING AVENUE
		CITY:			SOUTH PORTLAND
		STATE:			ME
		ZIP:			04106
		BUSINESS PHONE:		(207) 773-8171

	MAIL ADDRESS:	
		STREET 1:		97 DARLING AVENUE
		CITY:			SOUTH PORTLAND
		STATE:			ME
		ZIP:			04106

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	Wright Express CORP
		DATE OF NAME CHANGE:	20041118

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Smith Melissa D
		CENTRAL INDEX KEY:			0001317498

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-32426
		FILM NUMBER:		17675176

	MAIL ADDRESS:	
		STREET 1:		C/O WRIGHT EXPRESS CORPORATION
		STREET 2:		97 DARLING AVENUE
		CITY:			SOUTH PORTLAND
		STATE:			ME
		ZIP:			04106

	FORMER NAME:	
		FORMER CONFORMED NAME:	Goodwin Melissa D
		DATE OF NAME CHANGE:	20050211
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_148900726645559.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-03-06</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001309108</issuerCik>
        <issuerName>WEX Inc.</issuerName>
        <issuerTradingSymbol>WEX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001317498</rptOwnerCik>
            <rptOwnerName>Smith Melissa D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O WEX INC.</rptOwnerStreet1>
            <rptOwnerStreet2>97 DARLING AVENUE</rptOwnerStreet2>
            <rptOwnerCity>SOUTH PORTLAND</rptOwnerCity>
            <rptOwnerState>ME</rptOwnerState>
            <rptOwnerZipCode>04106</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO and President, WEX Inc.</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Units</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.0</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2017-03-06</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>28672</value>
                </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>28672.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>28672</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">This award was granted as a performance stock unit.  The Compensation Committee of the Company's Board of Directors certified that the performance criteria established in connection with this grant had been met as of March 6, 2017. As a result of achieving the performance criteria the award converted from a PSU to an RSU and the reporting person's right to these units was established.</footnote>
        <footnote id="F2">RSUs vest with respect to this award on 3/15/2017.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Gregory Wiessner, as attorney-in-fact for Melissa D. Smith</signatureName>
        <signatureDate>2017-03-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
