<SEC-DOCUMENT>0000886346-15-000080.txt : 20150316
<SEC-HEADER>0000886346-15-000080.hdr.sgml : 20150316
<ACCEPTANCE-DATETIME>20150316111730
ACCESSION NUMBER:		0000886346-15-000080
CONFORMED SUBMISSION TYPE:	4/A
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20150309
FILED AS OF DATE:		20150316
DATE AS OF CHANGE:		20150316

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			KADANT INC
		CENTRAL INDEX KEY:			0000886346
		STANDARD INDUSTRIAL CLASSIFICATION:	SPECIAL INDUSTRY MACHINERY (NO METALWORKING MACHINERY) [3550]
		IRS NUMBER:				521762325
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0103

	BUSINESS ADDRESS:	
		STREET 1:		ONE TECHNOLOGY PARK DRIVE
		CITY:			WESTFORD
		STATE:			MA
		ZIP:			01886
		BUSINESS PHONE:		(978) 776-2000

	MAIL ADDRESS:	
		STREET 1:		ONE TECHNOLOGY PARK DRIVE
		CITY:			WESTFORD
		STATE:			MA
		ZIP:			01886

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	THERMO FIBERTEK INC
		DATE OF NAME CHANGE:	19930328

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Langevin Eric T
		CENTRAL INDEX KEY:			0001354978

	FILING VALUES:
		FORM TYPE:		4/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-11406
		FILM NUMBER:		15701642

	MAIL ADDRESS:	
		STREET 1:		KADANT INC.
		STREET 2:		ONE ACTON PLACE, SUITE 202
		CITY:			ACTON
		STATE:			MA
		ZIP:			01720
</SEC-HEADER>
<DOCUMENT>
<TYPE>4/A
<SEQUENCE>1
<FILENAME>wf-form4a_142651904092861.xml
<DESCRIPTION>FORM 4/A
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2015-03-09</periodOfReport>

    <dateOfOriginalSubmission>2015-03-12</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000886346</issuerCik>
        <issuerName>KADANT INC</issuerName>
        <issuerTradingSymbol>KAI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001354978</rptOwnerCik>
            <rptOwnerName>Langevin Eric T</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>KADANT INC.</rptOwnerStreet1>
            <rptOwnerStreet2>ONE TECHNOLOGY PARK DRIVE</rptOwnerStreet2>
            <rptOwnerCity>WESTFORD</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>01886</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EXECUTIVE VICE PRESIDENT, COO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2015-03-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1125</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>47.50</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>28978</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2015-03-12</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1375</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>47.50</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>34889</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The transactions reported on this Form 4 were executed pursuant to a Rule 10-b-5-1 trading plan adopted November 21, 2014.</footnote>
        <footnote id="F2">This amendment corrects an error in reporting the sale of shares of March 12, 2015.  The original Form 4 reported the sale of 2500 shares on March 12, 2015.  The reporting person was subsequently informed by the broker after the filing that 1,125 shares were sold on March 9, 2015 and only 1,375 shares were sold on March 12, 2015.  Both sales were completed at $47.50 per share pursuant to a Rule 10b-5-1 trading plan adopted November 21, 2014.  In all other respects the form is unchanged.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Sandra L. Lambert for Eric T. Langevin</signatureName>
        <signatureDate>2015-03-16</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
