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                             September 28, 2021

       Michael Larsen
       Chief Financial Officer
       Illinois Tool Works, Inc.
       155 Harlem Avenue
       Glenview IL 60025

                                                        Re: Illinois Tool
Works, Inc.
                                                            Form 10-K for the
Year Ended December 31, 2020
                                                            Filed February 12,
2021
                                                            Form 10-Q/A for the
Quarterly Period Ended June 30, 2021
                                                            Filed August 6,
2021
                                                            Form 8-K filed July
30, 2021
                                                            File No. 001-04797

       Dear Mr. Larsen:

              We have reviewed your filings and have the following comments. In
some of our
       comments, we may ask you to provide us with information so we may better
understand your
       disclosure.

              Please respond to these comments within ten business days by
providing the requested
       information or advise us as soon as possible when you will respond. If
you do not believe our
       comments apply to your facts and circumstances, please tell us why in
your response.

                                                        After reviewing your
response to these comments, we may have additional comments.

       Form 10-K for the Year Ended December 31, 2020

       Item 7. Management's Discussion and Analysis of Financial Condition and
Results of Operations
       Consolidated Results of Operations, page 22

   1.                                                   In connection with your
year-over-year discussion of Free cash flow on pages 23-24,
                                                        please present with
equal or greater prominence, the most directly comparable liquidity
                                                        measure calculated and
presented in accordance with Generally Accepted Accounting
                                                        Principles (GAAP).
Refer to Item 10(e)(1)(i)(A) of Regulation S-K.
 Michael Larsen
Illinois Tool Works, Inc.
September 28, 2021
Page 2
Form 10-Q/A for the Quarterly Period Ended June 30, 2021

After-tax Return on Average Invested Capital, page 27

2.       Please make clear what measures you deem as GAAP versus non-GAAP and
provide the
         appropriate captions. Please reconcile the non-GAAP measure(s) to the
most directly
         comparable financial measure(s) calculated and presented in accordance
with GAAP.
         Refer to Item 10(e)(1)(i)(B) of Regulation S-K.

         Additionally, please disclose how you derived "Average invested
capital" and "After-tax
         return on average invested capital." It appears that After-tax return
is based on an
         annualized amount (i.e., TTM or similar).

Form 8-K filed July 30, 2021

Exhibit 99.1
GAAP to Non-GAAP Reconciliation (Unaudited)
Free Cash Flow (Unaudited), page 7

3.       We note your presentation of Free cash flow to net income conversion
rate. Please
         present with equal or greater prominence, the most directly comparable
financial
         ratio calculated and presented in accordance with GAAP. Further
disclose the reasons why
         you believe that presentation of the non-GAAP financial measure
provides useful
         information to investors. Refer to Item 10(e)(1)(i)(A) and (C) of
Regulation S-K.
        We remind you that the company and its management are responsible for
the accuracy
and adequacy of their disclosures, notwithstanding any review, comments, action
or absence of
action by the staff.

        You may contact Kathryn Jacobson, Senior Staff Accountant at (202)
551-3365 or Robert
Littlepage, Accountant Branch Chief at (202) 551-3361 if you have questions
regarding
comments on the financial statements and related matters.




FirstName LastNameMichael Larsen                            Sincerely,
Comapany NameIllinois Tool Works, Inc.
                                                            Division of
Corporation Finance
September 28, 2021 Page 2                                   Office of
Technology
FirstName LastName