How to Compare Two Documents in Microsoft Word

To compare two documents in Microsoft Word, navigate to the Review tab on the ribbon, click Compare, and select Compare Documents. Choose your base file under Original document, select your updated file under Revised document, and click OK to generate a redline document showing all insertions, deletions, and formatting changes.

Step-by-Step Instructions to Compare Two Documents in Microsoft Word

Microsoft Word includes a built-in comparison utility designed to analyze two versions of a file and highlight every difference using revision marks. Whether you are reviewing contracts, academic papers, or policy drafts, using this automated feature ensures that no untracked edit goes unnoticed.

To perform a standard document comparison, follow these steps:

1. Open Microsoft Word on your computer. You can open a blank document or start from an existing draft.
2. Navigate to the top menu ribbon and click on the Review tab.
3. In the Compare group, click the Compare button. From the drop-down menu, select Compare Documents (or Compare).
4. A dialog box titled Compare Documents will appear on your screen.
5. Under the Original document section on the left, click the folder icon to browse your file directory and select your base document.
6. Under the Revised document section on the right, click the folder icon to browse and select the updated version of the file that contains edits.
7. Click the More button at the bottom of the dialog box to expand the advanced comparison options and customize how Word tracks edits.
8. Under the Show changes at section, choose whether to display differences at the Word level or Character level.
9. Under the Show changes in section, ensure that New document is selected. This ensures your original base file and revised file remain untouched while generating a third standalone document for the markup.
10. Click OK. Word will process both files and open a new window containing the combined redline document.

If you are using Word on a Mac, you can also access this function via the application menu. Point to Tools on the menu bar, navigate to Track Changes, select Compare Documents, and click the options button to adjust your settings before running the comparison.

Once the comparison runs, Word displays deletions with strikethrough formatting, insertions with underlines, and shifted text as moved content. You can use the Review tab to step through each change individually, accepting or rejecting modifications in bulk to finalize your document.

A Complete Worked Example Comparing Two Draft Agreement Documents

To understand how Word processes file differences, consider a practical contract review scenario involving two versions of a non-disclosure agreement clause.

Inputs for the Comparison

• Original Document (Contract_Draft_v1.docx): “This Agreement is effective as of January 1, 2026 between Acme Corp. and the Recipient, who agrees to keep all Confidential Information secret for five (5) years, and report any unauthorized use, loss or accidental release within thirty (30) days of discovering it, and cooperate in any investigation.”

• Revised Document (Contract_Draft_v2.docx): “This Agreement is effective as of January 1, 2026 between Acme Corp. and the Recipient, who agrees to keep all Confidential Information secret for three (3) years, and report any unauthorized use, loss or accidental release within ten (10) days of discovering it, and cooperate in any investigation.”

Step-by-Step Execution

1. Open Word and click Review > Compare > Compare Documents.
2. Select Contract_Draft_v1.docx as the Original document.
3. Select Contract_Draft_v2.docx as the Revised document.
4. Click More >> to open the detailed settings panel.
5. Select Word level tracking under Show changes at, leave all comparison items checked, and set Show changes in to New document.
6. Click OK to initiate the comparison algorithm.

Resulting Output in the New Redline Document

Word generates a brand-new document displaying the merged text with tracked changes:

“This Agreement is effective as of January 1, 2026 between Acme Corp. and the Recipient, who agrees to keep all Confidential Information secret for five (5) three (3) years, and report any unauthorized use, loss or accidental release within thirty (30) ten (10) days of discovering it, and cooperate in any investigation.”

In this markup view:

• The deleted term “five (5)” appears with a red strikethrough.
• The inserted term “three (3)” appears directly after it with a red underline.
• The deleted timeframe “thirty (30)” appears with a red strikethrough.
• The inserted timeframe “ten (10)” appears with a red underline.
• Unchanged text remains completely intact without revision marks.
• The original file Contract_Draft_v1.docx and the revised file Contract_Draft_v2.docx remain unaltered on your storage drive.

Advanced Settings and Key Inputs That Change Your Comparison Results

Word’s built-in comparison tool offers several configuration options that alter how changes are flagged, categorized, and displayed. Accessing these settings through the More button in the Compare Documents dialog box allows you to tailor the output to your specific document review requirements.

1. Comparison Settings Checkboxes

Under the Comparison settings menu, Word provides checkboxes for specific element types:

• Moves: Detects when text blocks are relocated within the document rather than deleted and re-inserted.
• Formatting: Tracks changes to font style, font size, bold, italics, line spacing, and paragraph margins.
• Case changes: Highlights modifications in capitalization, such as changing lowercase letters to uppercase.
• White space: Tracks added or removed spaces and tab characters.
• Tables, Headers, Footers, Footnotes, and Comments: Controls whether structural elements and annotations are included in the revision scan.

2. Character-Level vs. Word-Level Tracking

Word allows you to specify the granularity of revision markup:

• Word-level tracking: When a single letter inside a word is modified, Word marks the entire original word as deleted and inserts the new word. For example, changing “capital” to “capitol” strikes through “capital” and underlines “capitol”.
• Character-level tracking: Word isolates and highlights only the specific letters that changed. In the “capital” to “capitol” example, only the letter “a” is struck through and the letter “o” is underlined. Character-level detail is especially useful for proofreading legal definitions, technical specifications, or code numbers.

3. Displaying Changes in Documents

You can choose where Word outputs the comparison results:

• Original document: Overlays revision marks directly onto the base file.
• Revised document: Overlays revision marks onto the updated file.
• New document: Creates a separate third file containing the full redline markup, leaving both source files unchanged. Creating a new document is the safest approach for legal and professional auditing.

4. Comparing vs. Combining Documents

Word provides two distinct functions on the Review tab menu:

• Compare Documents: Takes two distinct versions of a single file (an original base file and a single revised file) and calculates the exact net differences between them.
• Combine Documents: Merges edits from multiple reviewers into a single document. If three separate team members provided feedback on the same draft, using Combine Documents under Review > Compare > Combine Documents merges their revision marks into one central master file.

Common Pitfalls and Edge Cases Where Comparison Yields Unexpected Results

While Word’s comparison engine is highly effective, certain document conditions or settings can produce confusing outputs, bloated markups, or inaccurate redlines. Understanding these edge cases helps you prevent errors during document review.

1. Bypassed Track Changes Locks

External reviewers often return drafts with Track Changes turned off, or they may bypass locked tracking mechanisms to make silent edits. Relying solely on visual checks or relying on the reviewer’s turned-on revision marks can lead to missed edits. Running a formal document comparison against your original base draft catches every untracked addition, deletion, or modification made by outside parties.

2. Global Formatting Overhead

If an external editor changes the font family, font size, or line spacing across an entire document, enabling the Formatting checkbox under Comparison settings creates hundreds of sidebar callouts reading “Formatted: Font: Name” or “Formatted: Line Spacing”. This visual clutter hides critical text deletions and insertions. If formatting adjustments are not essential to your review, unchecking the Formatting box in the More menu cleans up the view and focuses the redline strictly on wording changes.

3. Character vs. Word Level Confusion

Selecting word-level tracking when reviewing detailed technical text can result in excessive strikethroughs for minor typo fixes. Conversely, using character-level tracking on heavily rewritten paragraphs can make the redline difficult to read due to fractured letter-by-letter markups. Choosing the appropriate tracking level before running the utility prevents unreadable redline clutter.

4. Overwriting Original Source Files

If the Show changes in setting is accidentally set to Original document or Revised document, Word overwrites the selected file with revision marks. If you save the file after reviewing, you risk losing your clean original draft. Always verify that New document is selected before clicking OK.

5. Plain Text Snippet Comparison

When you only need to compare plain text snippets without opening Word or configuring document settings, using a quick Text Compare tool can save time before running a formal file review.

6. Scanned Documents and Non-Word File Formats

Word’s built-in Compare tool requires documents to be in compatible Word formats (.doc or.docx). If you attempt to compare a scanned PDF or an image-based document directly inside Word without converting it or running optical character recognition (OCR) text extraction first, Word cannot compare the embedded text. Converting scanned files into editable text or Word format prior to using the Compare Documents tool ensures all text and layout changes are properly recognized.