<SEC-DOCUMENT>0000049826-16-000279.txt : 20161123
<SEC-HEADER>0000049826-16-000279.hdr.sgml : 20161123
<ACCEPTANCE-DATETIME>20161123120549
ACCESSION NUMBER:		0000049826-16-000279
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		2
CONFORMED PERIOD OF REPORT:	20161122
FILED AS OF DATE:		20161123
DATE AS OF CHANGE:		20161123

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ILLINOIS TOOL WORKS INC
		CENTRAL INDEX KEY:			0000049826
		STANDARD INDUSTRIAL CLASSIFICATION:	GENERAL INDUSTRIAL MACHINERY & EQUIPMENT [3560]
		IRS NUMBER:				361258310
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		155 HARLEM AVENUE
		CITY:			GLENVIEW
		STATE:			IL
		ZIP:			60025
		BUSINESS PHONE:		8477247500

	MAIL ADDRESS:	
		STREET 1:		155 HARLEM AVENUE
		CITY:			GLENVIEW
		STATE:			IL
		ZIP:			60025

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Zimmerman Michael R.
		CENTRAL INDEX KEY:			0001630650

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-04797
		FILM NUMBER:		162015569

	MAIL ADDRESS:	
		STREET 1:		155 HARLEM AVE.
		CITY:			GLENVIEW
		STATE:			IL
		ZIP:			60025
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_147992073521809.xml
<DESCRIPTION>FORM 4
<TEXT>
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    <periodOfReport>2016-11-22</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000049826</issuerCik>
        <issuerName>ILLINOIS TOOL WORKS INC</issuerName>
        <issuerTradingSymbol>ITW</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001630650</rptOwnerCik>
            <rptOwnerName>Zimmerman Michael R.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>ILLINOIS TOOL WORKS INC.</rptOwnerStreet1>
            <rptOwnerStreet2>155 HARLEM AVENUE</rptOwnerStreet2>
            <rptOwnerCity>GLENVIEW</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60025</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Executive Vice President</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2016-11-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>9238</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>55.81</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>11016</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
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        <nonDerivativeTransaction>
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            <transactionDate>
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                <transactionPricePerShare>
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                <value>Employee Stock Option</value>
            </securityTitle>
            <conversionOrExercisePrice>
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            <exerciseDate>
                <value>2015-02-14</value>
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            <expirationDate>
                <value>2024-02-14</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
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                <underlyingSecurityShares>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
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        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Employee Stock Option</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>55.71</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2013-02-10</value>
            </exerciseDate>
            <expirationDate>
                <value>2022-02-10</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>10017.0</value>
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            <postTransactionAmounts>
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        <derivativeHolding>
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                <value>Employee Stock Option</value>
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            <conversionOrExercisePrice>
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            <exerciseDate>
                <value>2014-02-15</value>
                <footnoteId id="F2"/>
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            <expirationDate>
                <value>2023-02-14</value>
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            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>9325.0</value>
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            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>9325</value>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
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        <derivativeTransaction>
            <securityTitle>
                <value>Employee Stock Option</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>55.81</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2016-11-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionAmounts>
                <transactionShares>
                    <value>9238</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2012-02-11</value>
            </exerciseDate>
            <expirationDate>
                <value>2021-02-11</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
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        </derivativeTransaction>
        <derivativeHolding>
            <securityTitle>
                <value>Employee Stock Option</value>
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            <conversionOrExercisePrice>
                <value>98.26</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2016-02-13</value>
                <footnoteId id="F2"/>
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            <expirationDate>
                <value>2025-02-13</value>
            </expirationDate>
            <underlyingSecurity>
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        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Performance Restricted Stock Unit (granted 2/13/15)</value>
                <footnoteId id="F3"/>
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            <conversionOrExercisePrice>
                <value>0.0</value>
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            <exerciseDate>
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            <postTransactionAmounts>
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            <ownershipNature>
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        <derivativeHolding>
            <securityTitle>
                <value>Restricted Stock Unit (granted 02/14/2014)</value>
                <footnoteId id="F3"/>
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                <value>91.88</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2017-02-12</value>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2026-02-12</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
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                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>15817.0</value>
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            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>15817</value>
                </sharesOwnedFollowingTransaction>
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                    <value>D</value>
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        <derivativeHolding>
            <securityTitle>
                <value>Performance Restricted Stock Unit (granted 2/12/2016)</value>
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                <value>0.0</value>
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            <underlyingSecurity>
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    <footnotes>
        <footnote id="F1">This transaction was executed in multiple trades at prices ranging from $123.62 to $123.64. The price reported above reflects the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, Illinois Tool Works Inc. or a shareholder of Illinois Tool Works Inc. full information regarding the number of shares and prices at which the transaction was effected.</footnote>
        <footnote id="F2">Options vest in four (4) equal installments beginning one year from date of grant.</footnote>
        <footnote id="F3">Each restricted stock unit (RSU) and performance restricted stock unit (PRSU) represents a contingent right to receive one share of the Company's common stock.</footnote>
        <footnote id="F4">Each PRSU vests 100% three years from the date of grant if performance goals are met.</footnote>
        <footnote id="F5">Each RSU vests 100% three years from the date of grant.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Michael R. Zimmerman, by Janet O. Love, Deputy General Counsel &amp; Assistant Secretary, Attorney-In-Fact on File</signatureName>
        <signatureDate>2016-11-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
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<DOCUMENT>
<TYPE>EX-24
<SEQUENCE>2
<FILENAME>ex-24.htm
<DESCRIPTION>POWER OF ATTORNEY- ZIMMERMAN
<TEXT>
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<pre>
POWER OF ATTORNEY

The undersigned hereby constitutes and appoints each of E. Scott Santi, Michael M. Larsen, and Janet O. Love signing singly, his true and lawful attorney-in-fact to:

(1)    execute for and on behalf of the undersigned Forms 3, 4 and 5 in accordance with Section 16(a) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), and the rules thereunder;

(2)    do and perform any and all acts for and on behalf of the undersigned which may be necessary or desirable to complete the execution of any such Form 3, 4 or 5 and the timely filing of such form with the United States Securities and Exchange Commission ("SEC") and any other person; and

(3)    take any other action of any type whatsoever in connection with the foregoing which, in the opinion of such attorney-in-fact, may be of benefit to, in the best interest of, or legally required by, the undersigned, it being understood that the documents executed by such attorney-in-fact on behalf of the undersigned pursuant to this Power of Attorney shall be in such form and shall contain such terms and conditions as such attorney-in-fact may approve in his discretion.

The undersigned acknowledges that the foregoing attorneys-in-fact, in serving in such capacity at the request of the undersigned, are not assuming any of the undersigned's responsibilities to comply with Section 16 of the Exchange Act.

This Power of Attorney shall be effective on the date set forth below and shall continue in full force and effect until the date on which the undersigned shall cease to be subject to Section 16 of the Exchange Act and the rules thereunder or until such earlier date on which written notification executed by the undersigned is filed with the SEC expressly revoking this Power of Attorney.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be executed as of this 26th day of October 015.



/s/ Michael R. Zimmerman
Michael R. Zimmerman

Signed and sworn to before me on
this 26th day of October 2015.

/s/ Meghan P. Callero
Notary Public
</pre>
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