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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2007-02-27</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001352341</issuerCik>
        <issuerName>Verigy Ltd.</issuerName>
        <issuerTradingSymbol>vrgy</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001364097</rptOwnerCik>
            <rptOwnerName>Erickson Gayn</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>10100 NORTH TANTAU AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CUPERTINO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>95014</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Vice President, Memory Test</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Employee Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>23.42</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2007-02-27</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>11250</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2007-05-27</value>
            </exerciseDate>
            <expirationDate>
                <value>2013-12-12</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Ordinary Shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>11250</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>11250</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">This is the 2nd tranche of an option award that is divided into four grants, each comprised of 25% of the total number of shares subject to the award.  The first tranche was granted 12/13/2006 and becomes exercisable in 16 equal quarterly installments from the grant date; this 2nd tranche becomes exercisable in 15 equal quarterly installments from the date of grant; the third tranche will be granted as of the 3rd business day following Verigy's announcement of its financial results for the quarter ending 4-30-07, and will become exercisable in 14 equal quarterly installments from the date of grant; and the 4th tranche will be granted as of the third business day following Verigy's announcement of its financial results for the quarter ending 7-31-07, and will become exercisable in 13 equal quarterly installments from the date of grant.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Gayn Erickson by Paul R. Moore, Attorney-In-Fact</signatureName>
        <signatureDate>2007-03-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
