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

    <schemaVersion>X0305</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2012-06-22</periodOfReport>

    <issuer>
        <issuerCik>0000886158</issuerCik>
        <issuerName>BED BATH &amp; BEYOND INC</issuerName>
        <issuerTradingSymbol>BBBY</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001191821</rptOwnerCik>
            <rptOwnerName>ADLER DEAN S</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O LUBERT-ADLER PARTNERS, L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>2929 ARCH STREET, 29TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>PHILADELPHIA</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>19104</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, $.01 par value per share</value>
            </securityTitle>
            <transactionDate>
                <value>2012-06-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1478</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>60.93</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>17030</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents an automatic grant of restricted stock under the Company's 2012 Incentive Compensation Plan valued at $90,000, issued as part of annual director compensation and approved by the Board of Directors of the Company on June 22, 2012.  The number of shares was determined based on a stock price of $60.93, the average of the high and low trading prices of the Company's common stock on June 22, 2012, the date of the Company's Annual Meeting of Shareholders.  The restricted stock will vest on the first trading day following the expiration of any applicable blackout period following the last day of the fiscal year of grant, provided that the director remains in office until the last day of the fiscal year.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Ori Solomon, Attorney-in-Fact</signatureName>
        <signatureDate>2012-06-26</signatureDate>
    </ownerSignature>
</ownershipDocument>
