How to Compare Two Word Documents Side-by-Side to Find Differences

If you email a contract to a colleague for review, they are supposed to turn on “Track Changes” before editing it, so you can clearly see exactly what paragraphs they deleted or modified. However, colleagues rarely remember to do this. Often, they will simply open the document, make silent edits, save the file as “Contract_Final_V2.docx,” and email it back to you.

You are now left with two 50-page documents that look identical, but one contains a hidden, critical change. Reading both documents line-by-line to find the difference is an impossible task.

Fortunately, Microsoft Word features a powerful, automated “Compare” tool designed specifically for this scenario. It acts like a forensic auditor, instantly scanning both files and generating a third document that aggressively highlights every single deleted comma, added word, or formatting change.

This guide explains how to use the Compare tool in Microsoft Word.

Step 1: Open the Compare Tool

You do not actually need to have either of the documents open to start this process. You can begin from a completely blank Word document.

1. Open Microsoft Word.
2. Look at the main ribbon at the top of the screen and click on the Review tab.
3. Look toward the far right side of the ribbon for the “Compare” group. Click the Compare button (the icon looks like two pieces of paper stacked together).
4. From the drop-down menu that appears, click Compare… (Compare two versions of a document).

Step 2: Select Your Two Documents

A small dialog box titled “Compare Documents” will appear, divided into two distinct halves.

1. On the left side, under Original document, click the small yellow folder icon. Use the file browser to locate and select your original, unedited file.
2. On the right side, under Revised document, click the small yellow folder icon and select the modified file your colleague emailed back to you.
3. At the bottom of the dialog box, you will see an option labeled “Show changes in”. Ensure this is set to New document so Word does not accidentally overwrite your original files.
4. Click the OK button.

Step 3: Review the Differences

Word will freeze for a moment while it analyzes the text. When it finishes, your screen will split into a complex dashboard consisting of three separate panels.

• Right Panel (The Source Files): This panel is split horizontally. The top half displays a tiny, read-only view of your Original document. The bottom half displays a tiny, read-only view of the Revised document. They are locked together; if you scroll down on one, the other scrolls automatically.
• Center Panel (The Result): This is a brand new, third document. It contains the merged text of both files. Any text that your colleague deleted will be crossed out with a red strike-through line. Any text that your colleague added will be underlined in red.
• Left Panel (The Summary Revisions Pane): This acts as a table of contents for the edits. It tells you exactly how many total insertions, deletions, and formatting changes occurred. You can click on any individual edit in this list, and the center panel will instantly snap to that exact paragraph, allowing you to quickly audit a massive document in seconds.