Compare Two Documents in Word: Create a Redline

To compare two documents in Microsoft Word and create a redline, open Word for Microsoft 365 on Windows, select Review > Compare > Compare, choose the earlier file as the original and the later file as the revised document, then select OK. Word creates a separate comparison document showing the differences as tracked changes; your two source files remain unchanged. Check the comparison and save it under a new name before sharing it.

What You’ll Need

Both document files. Keep a copy of the version before editing and the version after editing. Word compares files such as .docx; if a file is in an older or different format, open it in Word and save a copy as a Word document first.
Microsoft Word desktop. The steps below use Word for Microsoft 365 on Windows. Word for the web does not provide the same full Compare workflow, so open the files in the desktop app. On Mac, the Compare command is also on the Review tab, though the dialog layout can differ.
A clear idea of which file is earlier. You can still compare in either order, but choosing the earlier version as Original and the later one as Revised makes the redline easier to interpret.
A place to save the result. Word creates a new comparison document. Decide on a filename and location for it, separate from the two source documents.

Step-by-Step

Identify and preserve the two versions. Locate the original and revised files before starting. If they have similar names, check their dates or open each one and verify a distinctive sentence. Avoid making last-minute edits to either source while the comparison is underway. Word compares the content in the files you select; it does not automatically know which one should be treated as the earlier version. Save a backup if the files are important, and close duplicate copies if you are unsure which version is current.
Open Word and go to the Compare command. In Word for Microsoft 365 on Windows, open Word and select the Review tab on the ribbon. In the Compare group, select Compare, then choose Compare from the menu. Do not choose Combine unless you are consolidating edits from separate reviewers; Compare is the command for identifying differences between two document versions. If the ribbon is simplified or the window is narrow, expand the ribbon or use Word’s command search to find Compare.
Select the earlier file as the original. In the Compare Documents dialog, use the folder or browse button beside Original document to locate and select the earlier version. Confirm the filename shown in the field. If both versions are open, use the selection list if available, but still verify that you have chosen the intended file. Assigning the wrong file here can make additions appear as deletions and vice versa, even though Word is still identifying the differences correctly.
Select the later file as the revised version. Browse beside Revised document and select the version containing the updates. Check that the original and revised fields do not point to the same file. The revised document is the reference for changes made since the original: inserted material is generally shown as an addition, while removed material is shown as a deletion. If the work happened in several stages, choose the pair that answers the question you need to review, such as what changed between the approved draft and the current draft.
Set the comparison label. The dialog includes a field for labeling changes, often shown as Label changes with. Enter a useful name, such as the editor’s name or “Draft comparison,” so readers can tell whose comparison markup they are viewing. This label identifies the changes in the generated comparison; it does not certify who actually made every edit. If the dialog shows a default name, replace it if that would be confusing to reviewers.
Review the comparison settings. Select More in the dialog to see additional options. You can choose which kinds of differences to include, such as text changes, formatting, comments, tables, headers and footers, footnotes and endnotes, or text boxes; available choices can vary by Word version. Leave relevant categories selected. If you only want to review wording, you may turn off formatting comparison to reduce visual noise. The setting for showing changes at the word or character level controls how text edits are grouped: word-level markup is often easier to read, while character-level markup can reveal small edits inside a word. If you are unsure, keep the defaults and inspect the result before changing settings.
Choose where Word displays the comparison. Word normally creates the comparison in a new document. If the dialog offers a choice to show changes in a new document, the original, or the revised document, select New document. This keeps your source versions untouched and gives you a standalone redline to review. Avoid directing the comparison into a source file unless you have a specific reason and a backup, because a new file is safer for normal review and sharing.
Run the comparison and inspect the result. Select OK. Word opens the comparison document with changes marked, typically using tracked-change formatting. Review the document from beginning to end. Look at the markup in the main text and check any comments, headers, footers, tables, or footnotes that matter to your work. Use the Review tab’s change-navigation controls, such as Previous and Next, to move through revisions. The markup is a review aid, not a judgment about whether a change is correct.
Save the redline as a separate file. Select File > Save As (or File > Save a Copy, depending on the Word interface), choose a location, and give the result a descriptive name such as Proposal_redline_2026-11-03.docx. Confirm that the file type is a Word document if you want editable tracked changes. Keep the original and revised files as separate records. If you need a clean reading copy, save another copy and resolve the changes there; do not overwrite the redline you may need for review.

Common Mistakes

Reversing the original and revised files. This usually does not prevent Word from finding differences, but it can reverse the apparent direction of edits. For a conventional redline, use the earlier version as Original and the later version as Revised.

Comparing the wrong copies. Files named “final,” “final2,” or “latest” can be easy to confuse. Check the contents or dates, not just the name. If the output seems to show unexpected changes throughout, verify both selected files before interpreting the markup.

Expecting the result to be a clean document. Compare creates a review document with markup, not a merged, approved final. Do not send it as a clean copy without checking the audience’s needs and the document’s review status.

Ignoring formatting or other categories. If formatting comparison is selected, font or layout differences may produce many marks alongside text edits. Conversely, switching off categories can hide differences you intended to check. Review the settings before comparing and rerun the comparison if you omitted something important.

Editing the only redline copy without saving. Accepting or rejecting revisions changes the review state. Save a separate copy before resolving changes, especially if another person needs to see the original comparison.

Tips

Use informative filenames that include the project or document name and version date. For example, distinguish “contract_approved” from “contract_vendor_edits” rather than relying on “new” and “old.”
For a large document, review the redline in sections and use Previous/Next to jump between revisions. Check the Navigation or Reviewing Pane if it is available in your version; it can help you locate changes without scrolling through every page.
Choose word-level comparison for ordinary editorial review when it makes the markup easier to read. Use character-level comparison when exact spelling, punctuation, or small in-word edits matter.
When the two files have substantially different layouts, focus first on substantive text changes. Layout shifts can make a comparison look busier than the underlying edits warrant.
Keep a record of the two input versions and the date of the comparison. That makes it easier for colleagues to understand what the redline represents later.
If you need to share a read-only view, export a copy of the reviewed redline to PDF after checking the page layout. Keep the editable .docx redline as well if reviewers may need to respond to or resolve changes.

Troubleshooting

Compare is missing or unavailable. Confirm that you are using Word’s desktop app rather than Word in a browser, and select the Review tab. If the ribbon is collapsed, expand it; if the window is narrow, some controls may be tucked into a menu. On Mac, open the Review tab and look for Compare or Compare Documents; wording and placement can vary slightly by release. If the feature still does not appear, check that the document is open in an editable format and that your Word installation is up to date.

Word says a file cannot be opened or compared. Open each source file separately. If Word prompts you to repair it, follow the prompt only after keeping a backup. For a non-Word file, use File > Open to open it in Word, then save a new .docx copy and compare those copies. Password-protected or restricted documents may require the password or permission to open before they can be selected.

The result shows too many changes. Check whether formatting, comments, or other comparison categories are included. Rerun Compare with only the categories you need. Also check whether one source was reflowed, converted, or reformatted; a layout-only change can generate lots of markup. Do not discard the result until you have confirmed that the extra marks are not substantive.

The comparison appears to show no changes. Verify that the selected files are actually different and that you did not choose the same file twice. Check that the relevant categories are enabled, and make sure you are viewing the comparison document rather than one of the originals. If the differences are limited to formatting, a setting that excludes formatting may explain why no marks appear; rerun with that category selected.

Changes or comments seem to be missing. Expand the display options in the Review tab and make sure Word is showing the relevant markup, rather than a simplified view such as No Markup. Also inspect the Compare dialog’s categories. A hidden display setting can make revisions appear absent even when they are present in the file. If a specific comment or note is essential, compare again with comments or the relevant content type included.

Frequently Asked Questions

Does Word’s Compare feature create a redline automatically?
Yes. It creates a new comparison document with differences marked for review, generally using tracked-change markup. You can navigate, accept, or reject revisions in that result without changing the two source files.

Is Compare the same as Track Changes?
No. Track Changes records edits made while it is turned on. Compare analyzes two existing document versions and generates markup showing their differences. Use Track Changes when you are editing a document and want future edits recorded; use Compare when you already have separate versions to reconcile.

Can I compare two Word documents online?
Word for the web does not offer the same full desktop Compare workflow. Open the documents in the Word desktop app and use Review > Compare. If you only have browser access, you may need to download the files and use desktop Word or another approved comparison tool.

Will comparing documents change or overwrite my originals?
Normally, no. Selecting New document creates a separate comparison file and leaves the source files intact. Save the generated redline with a new filename, and avoid choosing an original or revised document as the comparison destination unless you have a backup.

Can Word compare documents with different names or locations?
Yes. The filenames and folder locations do not need to match. Use the browse controls to select each file independently, then confirm that the correct version appears in the Original document and Revised document fields.

Can Word compare PDF files?
Word may be able to open and convert a PDF, but conversion can change page layout or formatting. For a more reliable comparison, open the PDF in Word, review the converted content, save a .docx copy, and compare that with the other Word version. Check the result carefully for conversion-related differences.

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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