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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-01-02</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000104889</issuerCik>
        <issuerName>Graham Holdings Co</issuerName>
        <issuerTradingSymbol>[GHC]</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001728606</rptOwnerCik>
            <rptOwnerName>Snyman Marcel A.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O GRAHAM HOLDINGS 1300 NORTH 17TH ST.</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 1700</rptOwnerStreet2>
            <rptOwnerCity>ARLINGTON</rptOwnerCity>
            <rptOwnerState>VA</rptOwnerState>
            <rptOwnerZipCode>22209</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>VP-Chief Accounting Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class B Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2019-01-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>200</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>500</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class B Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2019-01-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>100</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>633.07</value>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>400</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Class B shares awarded as restricted stock under incentive plan</footnote>
        <footnote id="F2">N/A</footnote>
        <footnote id="F3">The price reported in column 4 is a weighed average price.  These shares were sold in multiple transactions at prices ranging from 633.00 to 633.18.  The reporting person undertakes to provide to Graham Holdings Company, any security holder of Graham Holdings Company, or the staff of the Securities and Exchange Commission, upon request, full information regarding the shares sold.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Marcel A. Snyman</signatureName>
        <signatureDate>2019-01-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0306
4
2018-01-02
0
0000104889
Graham Holdings Co
[GHC]
0001728606
Snyman Marcel A.
C/O GRAHAM HOLDINGS 1300 NORTH 17TH ST.
SUITE 1700
ARLINGTON
VA
22209
0
1
0
0
VP-Chief Accounting Officer
Class B Common Stock
2019-01-02
4
A
0
200
A
500
D
Class B Common Stock
2019-01-02
4
S
0
100
633.07
D
400
D
Class B shares awarded as restricted stock under incentive plan
N/A
The price reported in column 4 is a weighed average price.  These shares were sold in multiple transactions at prices ranging from 633.00 to 633.18.  The reporting person undertakes to provide to Graham Holdings Company, any security holder of Graham Holdings Company, or the staff of the Securities and Exchange Commission, upon request, full information regarding the shares sold.
Marcel A. Snyman
2019-01-04