How to compare two documents in Word on Mac: step by step for Microsoft 365

What you need before you compare

You need Word for Microsoft 365 for Mac and both files saved as Word documents. If one file is a PDF or an older format, open it in Word and save a copy as a Word document first. The file picker in the Compare dialog works best with Word files.

Check your build before you start. Open Word and choose Word > About Word. Microsoft's update history lists build 16.114.4, released November 4, 2026, as the latest Word for Mac build. Menus move a little between builds, so the names on your screen may not match this guide word for word.

Pick the right file for each role

The dialog asks for two roles, and the order matters. The Original document is your baseline. The Revised document is the version with the edits you want to see. Most people set the older file as the Original, so each mark reads as a change made after that point.

Decide the roles before you open the dialog. If you swap them, insertions show up as deletions and the story of the edits reads backward. The table below covers the choices people usually get wrong.

Read the results without losing your originals

When the comparison finishes, Word opens a new document based on the original. Every difference appears as a revision mark. Microsoft says the original files are unchanged, so you can run the comparison again if the result looks wrong.

Save the new copy under a clear name before you edit anything. A name with both version names and a date saves you from guessing later. Work in the copy, and leave your source files alone.

Use the Review tab to move through the marks. Read the text around each one before you accept it. Accepting keeps the change in the copy. Rejecting removes it. Work from top to bottom, and reread the paragraph after each batch, since one edit can change the meaning of the next.

A worked example with two contract drafts

Say you have two drafts of a services agreement. Call them the older draft and the newer draft. The newer draft came back from your manager with edits, and you want the full difference before you reply.

Open the older draft in Word for Mac. Go to Review > Compare > Compare Documents, set the older draft as the Original and the newer draft as the Revised, then click OK. Word opens a new copy with marks. Scroll to the first mark, which might be a deleted clause. Accept the removals you agreed to, reject the ones you did not, and save the result under a new name.

Is there a keyboard shortcut for Compare Documents?

No, not one that Microsoft documents. Its keyboard shortcut list for Mac, under Review, has no entry for Compare Documents or Side by Side. The closest documented shortcut is ⌘⇧E, which turns Track Changes on or off. Use it when you want to track your own edits to the comparison copy.

Adjust how detailed the comparison is

Microsoft's Mac article describes a second route for detail settings. Go to Tools > Track Changes > Compare Documents, then click the down-arrow button for more options. That article says this is how you change the comparison settings or the detail level.

An older Microsoft tip uses the same route, so treat it as the legacy path. If your menus do not match, look for a more options control inside the Compare Documents dialog. Microsoft's legal blackline article for Windows lists a Show changes option, so expect the Mac names to differ.

Combine two versions into one document

Comparing and merging are different jobs. Compare shows you what changed between two files. Combine builds one document from both, with revision marks showing the proposed changes.

To merge, go to Review > Compare > Combine Documents. Pick the Original and Revised files as before. Word creates a new copy, and you decide what stays. Use Combine when you need one final text. Use Compare when you only need to read the differences.

Compare side by side on a Mac

This is where Mac users get stuck. Microsoft's side-by-side article covers View > View Side by Side and Synchronous Scrolling. It lists Windows versions and has no Mac note. A moderated Microsoft Q&A answer says Mac Word does not have a side-by-side option.

• Window > Move & Resize is the arrangement option Microsoft points to for Mac.
• Arrange All stacks windows vertically. The same Q&A thread gives conflicting advice on it, so test it before you rely on it.
• Split shows the same document twice in one window. It helps you read two parts of one file, not two files.
• Word for the web has no compare feature, so do side-by-side work in the desktop app.

A practical setup is simple. Open both files, use Window > Move & Resize to place them, then run Compare Documents when you need marks. The marks are easier to trust when you can see the source text next to them.

Fix greyed-out files in the Compare dialog

Since version 16.109, Word files can appear greyed out in the Compare Documents file picker. Microsoft's support article gives a workaround: click Show Options, then set Enable to All Files or to the type you need. The article was last updated May 18, 2026, and its status is workaround.

The workaround may not hold for everyone. A user who posted on July 26, 2026 said it stopped working on Word 16.111.1 with macOS Sequoia 15.7.7, and that Word crashes when Compare is selected. Microsoft does not confirm that report in the thread, so treat it as unconfirmed.

Using Compare with Word for the web

Word for the web does not offer the compare feature. Microsoft's browser page says so directly. For tracked changes, it tells you to click Open in Desktop. Open the file in the Mac app, then run Compare Documents there.

Mistakes that waste time

• Swapping the Original and Revised files, so the marks read backward.
• Editing one of the source files instead of the comparison copy.
• Stopping at greyed-out files when Show Options fixes the problem.
• Looking for a side-by-side button, which Mac Word does not document.
• Trusting a forum answer without checking your own Word build.

Most of these come from rushing the first two steps. Take a moment to set the roles and name the copy. The rest goes faster after that.

Why version mix-ups cost time

Pipeline's blog reports that 81% of knowledge workers found themselves working on a wrong version of a file. It cites a Harris Interactive survey through Business.com, with no sample size or date given. Treat that figure as a signal, not a measurement.

A labelled copy from each stage is cheap insurance. Compare gives you the marks, and the saved comparison copy gives you the record of what changed and what you decided.

What to do next

Once the marks are reviewed, save the final file under a new name. Keep the source files unchanged. If you want future edits in the final file tracked, turn on Track Changes in Word on Mac before you start editing.