<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2015-01-30</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000108516</issuerCik>
        <issuerName>WORTHINGTON INDUSTRIES INC</issuerName>
        <issuerTradingSymbol>WOR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001227159</rptOwnerCik>
            <rptOwnerName>ANDERSON KERRII B</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>200 OLD WILSON BRIDGE ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>COLUMBUS</rptOwnerCity>
            <rptOwnerState>OH</rptOwnerState>
            <rptOwnerZipCode>43085</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Shares</value>
            </securityTitle>
            <transactionDate>
                <value>2015-01-30</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>67</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>29.946</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>55957</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Shares</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>436</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Spouse</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Phantom Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F2"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F4"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>common shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>35</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3185</value>
                    <footnoteId id="F5"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Upon  review  of Ms. Anderson's account with her broker, it was found that an oversight occurred when an acquisition of 67 common shares were purchased on January 30, 2015 but not reported until now.  Ms. Anderson did not dispose of any Company common shares within six months of this purchase.</footnote>
        <footnote id="F2">The accounts track common shares on a one-for-one basis</footnote>
        <footnote id="F3">Prior to October 1, 2014, the account balance related to the theoretical Company common shares deemed investment option could be immediately transferred to other deemed investment options under the terms of the Worthington Industries, Inc. Amended and Restated 2005 Deferred Compensation Plan for Directors (the &quot;2005 Plan&quot;).</footnote>
        <footnote id="F4">The Company amended the 2005 Plan effective October 1, 2014.  The amendment includes a provision that, effective October 1, 2014 and thereafter, any amount credited in a participant's account to the phantom stock fund (i.e., the theoretical Company common shares deemed investment option) may not be transferred to an alternative deemed investment option under the 2005 Plan until distribution from the Plan.  Distributions are made only in common shares of the Company and generally commence upon a participant's leaving the Company's Board of Directors.</footnote>
        <footnote id="F5">The amount reported reflects 35 additional unfunded theoretical common shares (i.e., phantom stock) credited to the reporting person's account pursuant to the dividend reinvestment feature of the 2005 Plan since September 24, 2015.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/Dale T. Brinkman, as attorney-in-fact for Kerrii B. Anderson</signatureName>
        <signatureDate>2016-01-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
