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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-03-31</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001005210</issuerCik>
        <issuerName>SUBURBAN PROPANE PARTNERS LP</issuerName>
        <issuerTradingSymbol>SPH</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001227430</rptOwnerCik>
            <rptOwnerName>ABEL PAUL</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>SUBURBAN PROPANE</rptOwnerStreet1>
            <rptOwnerStreet2>240 ROUTE 10 WEST</rptOwnerStreet2>
            <rptOwnerCity>WHIPPANY</rptOwnerCity>
            <rptOwnerState>NJ</rptOwnerState>
            <rptOwnerZipCode>07981-0206</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Senior Vice President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Units (representing limited partnership interests)</value>
            </securityTitle>
            <transactionDate>
                <value>2017-03-31</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1393</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>27.15</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>60883</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <remarks>Represents filer's payment of tax liability in connection with the vesting of previously granted restricted units by means of Issuer's withholding of Common Units in accordance with the provisions of Issuer's restricted unit plan and SEC Rule 16b-3.</remarks>

    <ownerSignature>
        <signatureName>Paul Abel</signatureName>
        <signatureDate>2017-04-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
