<SEC-DOCUMENT>0001309108-17-000102.txt : 20170512
<SEC-HEADER>0001309108-17-000102.hdr.sgml : 20170512
<ACCEPTANCE-DATETIME>20170512200720
ACCESSION NUMBER:		0001309108-17-000102
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20170510
FILED AS OF DATE:		20170512
DATE AS OF CHANGE:		20170512

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:			Young Jeffrey Alan
		CENTRAL INDEX KEY:			0001670479

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-32426
		FILM NUMBER:		17840680

	MAIL ADDRESS:	
		STREET 1:		C/O WEX INC.
		STREET 2:		97 DARLING AVENUE
		CITY:			SOUTH PORTLAND
		STATE:			ME
		ZIP:			04106
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_149463402599892.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-05-10</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001670479</rptOwnerCik>
            <rptOwnerName>Young Jeffrey Alan</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>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>SVP, GM WEX Health</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>99.69</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2017-05-10</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>52281</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2027-05-10</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>52281.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>52281</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The performance-based stock option (right to buy) vests upon the attainment of specified stock price hurdles beginning on the third anniversary of the Grant Date, being May 10, 2020, and ending on the fifth anniversary of the Grant Date, being May 10, 2022 (&quot;Performance-Based NSOs&quot;). Each stock price requirement is as follows: (a) 50% of the total award vests if the Company closing stock price is at least $149.53 for twenty consecutive trading days;  (b) an additional 25% vests if the Company closing stock price is at least $174.45 for twenty consecutive trading days; and, (c) an additional 25% vests if the Company closing stock price is at least $199.38 for twenty consecutive trading days, in each instance so long at the reporting person remains employed with the company.  If the respective stock price hurdles are not reached by the fifth anniversary of the grant date, being May 10, 2022, the option does not vest at all.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Gregory Wiessner, as attorney-in-fact for Jeffrey A. Young</signatureName>
        <signatureDate>2017-05-12</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
