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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-10-09</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001501808</rptOwnerCik>
            <rptOwnerName>Weymouth Katharine</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1300 NORTH 17TH STREET</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 1700</rptOwnerStreet2>
            <rptOwnerCity>ARLINGTON</rptOwnerCity>
            <rptOwnerState>VA</rptOwnerState>
            <rptOwnerZipCode>22209</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class B Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-10-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1100</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>579.95</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3649</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The price reported in Column 4 is a weighed average price.  These shares were sold in multiple transactions at prices ranging from $579.90 to $580.25 inclusive.  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>Katharine Weymouth</signatureName>
        <signatureDate>2018-10-11</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0306
4
2018-10-09
0
0000104889
Graham Holdings Co
[GHC]
0001501808
Weymouth Katharine
1300 NORTH 17TH STREET
SUITE 1700
ARLINGTON
VA
22209
1
0
0
0
Class B Common Stock
2018-10-09
4
S
0
1100
579.95
D
3649
D
The price reported in Column 4 is a weighed average price.  These shares were sold in multiple transactions at prices ranging from $579.90 to $580.25 inclusive.  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.
Katharine Weymouth
2018-10-11