Compare and Merge Documents in Word: A Step-by-Step Guide

To compare two Word files, open Word and choose Review > Compare > Compare, then select the original and revised documents. Word creates a new document showing the differences as tracked changes. To combine separate edited copies, use Review > Compare > Combine instead. Keep the source files unchanged while you review the result.

What You’ll Need

Microsoft Word for Microsoft 365 desktop on Windows, or a desktop version of Word with the Compare and Combine tools.
The two documents you want to compare, preferably saved as .docx files. Decide which is the original and which is the revised copy before you start.
For a combined document, the common original and the separately edited copies. Combining works best when each editor started from the same base document.
A place to save the result under a new filename, so the originals remain available if you need to check them again.

Step-by-Step

Prepare the files. Save and close both documents, or at least save any open edits before comparing. Give the files clear names such as Project-original.docx and Project-revised.docx. Check that you have the intended versions: a file with a recent date is not necessarily the correct original. If the documents are in different formats, open each in Word and use File > Save As to save a working copy as a Word document. Avoid overwriting either source file.
Open Compare. In Word for Microsoft 365 on Windows, open a document or start Word, then select Review > Compare > Compare. If the Compare button is compressed on the ribbon, look in the Compare group or its drop-down. Word opens a dialog with fields for the original and revised documents. In some Word builds the command is labeled Compare Documents. On Mac, look under Review > Compare; the command may be called Compare Documents. The desktop app is needed for the full comparison controls; if you are using Word for the web, open the file in the desktop app.
Select the original and revised files. Use the folder buttons beside the document fields to browse to the files. Put the earlier or agreed-upon base version in Original document and the copy that contains newer edits in Revised document. Word uses this direction to identify insertions and deletions, so reversing the files can make the change marks read backward. Select More or More options if you need to adjust which kinds of content are checked.
Set the comparison options. The dialog can offer options for changes such as formatting, comments, case changes, tables, headers and footers, footnotes, or text boxes; the exact list depends on the Word version. Leave relevant categories selected if you want a thorough review. If you only care about wording, you can turn off formatting comparison to reduce distracting marks. Choose a label for unmarked changes if Word asks for one. Use a neutral label, such as Reviewer, unless you have a reason to identify a particular editor.
Choose where to show changes. Set the results to appear in a New document when that choice is available. This keeps both input files intact and gives you a separate comparison copy. Word may also let you display the result in the original or revised document, but those choices can make it easier to mistake the working file for a source. Confirm the selections, then click OK to run the comparison.
Review the comparison document. Word opens a new document with differences represented as tracked changes. Additions and deletions are marked, and the Reviewing Pane can help you inspect them in sequence. Use Review > Reviewing Pane to show or hide the pane, if that command is available in your ribbon layout. Click a change or move through the changes with the controls in the Review tab. Read the surrounding sentences, not only the highlighted words: a small edit can change a reference, date, or meaning elsewhere in a paragraph.
Save the comparison under a clear name. Choose File > Save As and save the result as a new file, for example Project-comparison.docx. If the comparison is part of a formal review, keep the tracked changes visible and share that copy with the reviewers. Do not accept every change just to make the page look clean; acceptance removes the visible record of that edit from the active review.
Combine separate copies when that is your goal. If two or more people edited their own copies of the same document, first compare each copy with the shared original or use Word’s combine function. In Word for Windows, choose Review > Compare > Combine. Select the original and one revised copy, check the labels and options, and choose to show changes in a new document if prompted. Click OK. Repeat for additional copies, combining each into the current combined result as appropriate. Review the result carefully for conflicting edits; Word can mark both versions, but it cannot decide which conflicting wording is correct.
Resolve and finalize edits. For each tracked change, choose Review > Accept or Review > Reject, using the individual-change controls when you need to make a decision one item at a time. If the result still needs another person’s approval, leave changes tracked and save it as a review copy. Once the decisions are complete, save a separate clean version. You can use Review > Display for Review to change how markup is displayed, but hiding markup does not remove the changes.

Common Mistakes

Swapping the original and revised files. Word treats the first selected document as the baseline. If you reverse the order, the same edit may appear as a deletion instead of an insertion. Check the file names and contents in the dialog before running Compare.

Assuming Compare edits the source files. A comparison is a review document, not a silent update of one file from another. Save the result separately, then accept or reject the marked changes to produce the version you actually want to use.

Using Combine for unrelated documents. Combine is intended for copies with a shared starting point. If the files were written independently or have substantially different structures, the result may contain a confusing mix of edits. Compare them first, or copy selected material into a deliberate master document.

Accepting all changes without checking context. A tracked insertion can conflict with a nearby deletion, and an apparently minor punctuation change can alter a list or cross-reference. Inspect comments and surrounding text before accepting or rejecting edits. Save a review copy before making large batches of decisions.

Thinking hidden markup is gone. A view such as No Markup can make a document look final while tracked edits remain stored in it. Check the review display and resolve changes deliberately before sending a clean copy to readers who should not see the review history.

Tips

Use consistent naming and keep a small set of source files together. For example, store the original, each editor’s copy, and the final combined file in one project folder with dates or version numbers in the names. Avoid names such as final-final because they do not show which file is the approved source.

Keep one untouched copy of the agreed original. If you need to rerun the comparison after correcting the file selection or options, you can start again without trying to reconstruct the baseline. Save the comparison before making review decisions, and use Ctrl+S regularly on Windows. On Mac, use Command+S.

For clearer results, ask collaborators to edit the same base document rather than rebuilding sections in separate files. If different people changed the same sentence, Word can show both edits, but a reviewer must choose or rewrite the final wording. Comments can explain why a change was made; they do not resolve a conflict by themselves.

Use the Reviewing Pane when the document has many changes, and consider reviewing one section at a time. You can also switch between markup views to make reading easier, but keep the changes visible while making decisions. If you send a comparison to someone else, tell them whether you want comments, tracked edits, or a clean final document.

Troubleshooting

Compare or Combine is missing. Confirm that you are using the Word desktop app rather than Word for the web, and that the Review tab is visible. The ribbon may be simplified or the window too narrow; expand the Word window or inspect the ribbon’s overflow menus. On Mac, check the Review tab for its Compare menu. If the feature is still absent, update Word and check whether your organization has customized or restricted the ribbon.

The result shows too many changes. Formatting differences can produce a large number of marks even when the wording is nearly identical. Run Compare again with formatting unchecked in the comparison options, if available. Also check whether one file has different styles, page numbering, headers, or layout settings that are causing noise.

Word reports that the documents cannot be compared. Open both files in Word and check whether either is password-protected, damaged, or in an unsupported format. Save accessible copies as .docx, close them, and try again. If a document is protected, you may need permission or an authorized unprotected copy; do not try to bypass a restriction you are not permitted to remove.

Changes appear in the wrong direction or the result looks incomplete. Reopen Compare and verify which file is selected as Original and which is Revised. Check whether relevant content types were excluded in the options. If you used Combine, confirm that the revised copies were based on the same original and repeat the process with the correct source files.

The document looks clean but changes remain. Switch the review display to show markup and inspect the tracked changes. A display setting can hide revisions without accepting them. If you need a genuinely clean file, make a separate copy and accept or reject each change, then save and reopen that copy to verify the result.

Frequently Asked Questions

Does Word’s Compare feature change either original document?
Normally, Compare creates a separate document containing the marked differences. Choose a new-document result and save it under a new name to preserve both inputs. Avoid selecting an option that displays results in a source file if you need to keep it untouched.

What is the difference between Compare and Combine in Word?
Compare identifies differences between two documents and presents them as tracked changes. Combine is designed to bring revisions from separately edited copies into one review document, typically when those copies share an original. Both results still need a person to review and resolve edits.

Can I compare two Word documents online?
Word for the web may let you view and edit documents, but the full Compare and Combine workflow is available in the desktop app. Open the files in desktop Word and use the Review tab for the comparison controls.

Can I compare documents with comments?
Yes. Depending on the version and options, Word can include comments in the comparison. Check the comparison options before running it, then inspect comments in the result. A comment is review context, not a replacement for deciding whether to accept or reject the associated edit.

How do I make the comparison into a final document?
Review the tracked changes and use Accept or Reject to decide each one. Save the resolved version under a new name, then show markup to confirm there are no unresolved revisions you intended to remove. Keep the original and comparison copy if you may need the review history later.

Try it: the Date Difference Calculator: days, months, years and weekdays between two dates, with the DATEDIF formulas.

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Sources: Function behaviour and menu paths: Microsoft Support documentation for Excel. Method & sources

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