<SEC-DOCUMENT>0001144215-19-000099.txt : 20190906
<SEC-HEADER>0001144215-19-000099.hdr.sgml : 20190906
<ACCEPTANCE-DATETIME>20190906163057
ACCESSION NUMBER:		0001144215-19-000099
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20190901
FILED AS OF DATE:		20190906
DATE AS OF CHANGE:		20190906

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			HOLCOM KAREN J
		CENTRAL INDEX KEY:			0001302261

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-16583
		FILM NUMBER:		191079980

	MAIL ADDRESS:	
		STREET 1:		1170 PEACHTREE STREET, NE
		STREET 2:		SUITE 2400
		CITY:			ATLANTA
		STATE:			GA
		ZIP:			30309

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ACUITY BRANDS INC
		CENTRAL INDEX KEY:			0001144215
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTRIC LIGHTING & WIRING EQUIPMENT [3640]
		IRS NUMBER:				582632672
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0831

	BUSINESS ADDRESS:	
		STREET 1:		1170 PEACHTREE STREET, NE
		STREET 2:		SUITE 2300
		CITY:			ATLANTA
		STATE:			GA
		ZIP:			30309-7676
		BUSINESS PHONE:		404-853-1400

	MAIL ADDRESS:	
		STREET 1:		1170 PEACHTREE STREET, NE
		STREET 2:		SUITE 2300
		CITY:			ATLANTA
		STATE:			GA
		ZIP:			30309-7676

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	L&C SPINCO INC
		DATE OF NAME CHANGE:	20010629
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>wf-form3_156780184212064.xml
<DESCRIPTION>FORM 3
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2019-09-01</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001144215</issuerCik>
        <issuerName>ACUITY BRANDS INC</issuerName>
        <issuerTradingSymbol>AYI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001302261</rptOwnerCik>
            <rptOwnerName>HOLCOM KAREN J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ACUITY BRANDS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>1170 PEACHTREE STREET, NE, SUITE 2300</rptOwnerStreet2>
            <rptOwnerCity>ATLANTA</rptOwnerCity>
            <rptOwnerState>GA</rptOwnerState>
            <rptOwnerZipCode>30309</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>SVP &amp; Chief Financial Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>15382</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>600.3032</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By 401(k) Plan</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Non-Qualified Stock Option</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>46.29</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2021-10-24</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1150.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Non-Qualified Stock Option</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>62.54</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2022-10-23</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2240.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Non-Qualified Stock Option</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>103.74</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2023-10-24</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1456.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Non-Qualified Stock Option</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>135.63</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <value>2024-10-27</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2004.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Non-Qualified Stock Option</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>207.8</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F6"/>
            </exerciseDate>
            <expirationDate>
                <value>2025-10-26</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1590.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Non-Qualified Stock Option</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>239.76</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F7"/>
            </exerciseDate>
            <expirationDate>
                <value>2026-10-24</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1794.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Non-Qualified Stock Option</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>156.39</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F8"/>
            </exerciseDate>
            <expirationDate>
                <value>2027-10-25</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1314.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Non-Qualified Stock Option</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>116.36</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F9"/>
            </exerciseDate>
            <expirationDate>
                <value>2028-10-24</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2936.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The total direct shares owned includes 8,866 time-vesting restricted shares and 4 shares held in the employee stock purchase plan.</footnote>
        <footnote id="F2">This option, granted on October 24, 2011, vested in equal annual installments over a three-year period and was fully vested on October 24, 2014.</footnote>
        <footnote id="F3">This option, granted on October 23, 2012, vested in equal annual installments over a three-year period and was fully vested on October 23, 2015.</footnote>
        <footnote id="F4">This option, granted on October 24, 2013, vested in equal annual installments over a three-year period and was fully vested on October 24, 2016.</footnote>
        <footnote id="F5">This option, granted on October 27, 2014, vested in equal annual installments over a three-year period and was fully vested on October 27, 2017.</footnote>
        <footnote id="F6">This option, granted on October 26, 2015, vested in equal annual installments over a three-year period and was fully vested on October 26, 2018</footnote>
        <footnote id="F7">This option, granted on October 24, 2016, vests in equal annual installments over a three-year period and will become fully vested on October 24, 2019.</footnote>
        <footnote id="F8">This option, granted on October 25, 2017, vests in equal annual installments over a three-year period and will become fully vested on October 25, 2020.</footnote>
        <footnote id="F9">This option, granted on October 24, 2018, vests in equal annual installments over a three-year period and will become fully vested on October 24, 2021.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Karen J. Holcom</signatureName>
        <signatureDate>2019-09-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
