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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2017-07-03</periodOfReport>

    <dateOfOriginalSubmission>2017-07-06</dateOfOriginalSubmission>

    <issuer>
        <issuerCik>0001591517</issuerCik>
        <issuerName>Time Inc.</issuerName>
        <issuerTradingSymbol>TIME</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001568037</rptOwnerCik>
            <rptOwnerName>Rolfe Ronald S</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TIME INC.</rptOwnerStreet1>
            <rptOwnerStreet2>225 LIBERTY STREET</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10281</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.01</value>
            </securityTitle>
            <transactionDate>
                <value>2017-07-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>8304</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>40451.432</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents restricted stock units that are scheduled to vest on the earlier of July 3, 2018 or the date of Time Inc.'s 2018 annual meeting of stockholders.  This amendment to the Form 4 filed on July 6, 2017 replaces in its entirety footnote 1 thereto to correct the vesting schedule for the award of restricted stock units reflected in the original report (repeated on this amendment to gain access to the filing system).</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Annette Boglev, Attorney-in-Fact for Ronald S. Rolfe</signatureName>
        <signatureDate>2017-07-07</signatureDate>
    </ownerSignature>
</ownershipDocument>
