<SEC-DOCUMENT>0001144215-19-000076.txt : 20190710
<SEC-HEADER>0001144215-19-000076.hdr.sgml : 20190710
<ACCEPTANCE-DATETIME>20190710160841
ACCESSION NUMBER:		0001144215-19-000076
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20190709
FILED AS OF DATE:		20190710
DATE AS OF CHANGE:		20190710

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			ROBINSON RAY M
		CENTRAL INDEX KEY:			0001183382

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-16583
		FILM NUMBER:		19949436

	MAIL ADDRESS:	
		STREET 1:		1170 PEACHTREE STREET NE
		STREET 2:		SUITE 2300
		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>4
<SEQUENCE>1
<FILENAME>wf-form4_156278930657146.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2019-07-09</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001183382</rptOwnerCik>
            <rptOwnerName>ROBINSON RAY M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ACUITY BRANDS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>1170 PEACHTREE STREET, NE, STE. 2300</rptOwnerStreet2>
            <rptOwnerCity>ATLANTA</rptOwnerCity>
            <rptOwnerState>GA</rptOwnerState>
            <rptOwnerZipCode>30309</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2019-07-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2363</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>130.15</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1429</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The price reported in Column 4 is a weighted average price.  These shares were sold in multiple transactions at prices ranging from $129.38 to $131.15, inclusive.  The Reporting Person undertakes to provide to Acuity Brands, Inc., any security holder of Acuity Brands, Inc., or the staff of the Security and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth herein.</footnote>
        <footnote id="F2">The total direct shares owned includes 429 time-vesting restricted shares.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Jill A. Gilmer under Power of Attorney for Ray M. Robinson</signatureName>
        <signatureDate>2019-07-10</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
