When you need to find differences between two versions of a contract, report, or manuscript, scrolling back and forth between separate windows is slow and error-prone. Word includes a built-in feature that places two documents on the same screen so you can review changes, verify edits, or check for consistency without switching tabs. This article explains how to use Word’s side-by-side view, how to synchronize scrolling between the files, and what to do when the comparison tools do not behave as expected.
Key Takeaways: Side-by-Side Document Comparison in Word
- View > Window > View Side by Side: Opens both open documents in adjacent panes for direct visual comparison.
- View > Window > Synchronous Scrolling: Locks the scroll position of both documents so they move together as you scroll either pane.
- Compare Documents under the Review tab: Generates a combined document that shows tracked changes between two files without manual side-by-side viewing.
What the Side-by-Side Feature Does and What You Need Before Using It
The side-by-side feature in Word places two open documents in separate vertical panes within the same application window. Each pane displays the full document content, and you can resize the panes by dragging the divider between them. The feature is designed for visual comparison only — it does not mark differences or generate a change log. You must open both documents before activating the view.
Word also provides a separate tool called Compare Documents under the Review tab. That tool analyzes two files and produces a third document that highlights all insertions, deletions, and formatting changes as tracked changes. While side-by-side view is useful for manual review, Compare Documents is better for automated difference detection. This article focuses on the side-by-side viewing method, but it covers the Compare Documents tool in the comparison table at the end.
No special permissions or add-ins are required. The feature works in Word for Microsoft 365, Word 2021, Word 2019, Word 2016, and Word for Mac. The steps below apply to Windows versions. Mac users should look for the same commands under the View tab in the Window group.
Steps to Open Two Word Documents Side by Side
Follow these steps to place two documents next to each other on the same screen. Both documents must be open in separate Word windows before you proceed.
Method 1: Using the View Side by Side Command
- Open both documents
Launch Word and open the first file. Then open the second file by going to File > Open or by dragging the file onto the Word taskbar icon. Each file opens in its own window. - Activate side-by-side view
Click inside the first document window. Go to the View tab on the ribbon. In the Window group, click the button labeled View Side by Side. Word automatically arranges both windows so they occupy the left and right halves of the screen. - Enable synchronous scrolling (recommended)
With side-by-side view active, the Synchronous Scrolling button in the Window group becomes available. Click it so it appears highlighted. Now when you scroll in either document, the other document scrolls at the same rate. Click the button again to turn off synchronized scrolling if you need to examine different sections independently. - Resize the panes
Move your mouse cursor to the vertical divider line between the two document panes. When the cursor changes to a double-headed arrow, click and drag the divider left or right to give more space to one document. - Exit side-by-side view
To return to the normal stacked window view, click the View Side by Side button again. Word deactivates the split and restores the documents to their previous window positions.
Method 2: Using the Arrange All Command
If you prefer to stack documents vertically instead of side by side, or if you have more than two documents open, use Arrange All instead.
- Open all documents you want to compare
Open each file in its own Word window as described in Method 1. - Click Arrange All
Go to the View tab and click Arrange All in the Window group. Word tiles all open document windows. If only two documents are open, they appear side by side by default. If three or more are open, Word arranges them in a grid. - Manually synchronize scrolling
Unlike View Side by Side, Arrange All does not offer a Synchronous Scrolling button. You must scroll each window separately. For this reason, View Side by Side is the better choice for comparing two documents.
Common Issues and Limitations With Side-by-Side Comparison
Word Does Not Show the View Side by Side Button
The View Side by Side button is grayed out or missing when only one document is open. Open a second document to enable the button. If the button remains grayed out after opening both documents, close Word completely and reopen both files. The issue usually occurs when a document opens in Protected View or Compatibility Mode. Save a copy of the file in the current .docx format and try again.
Documents Do Not Scroll Together
Synchronous Scrolling may become deactivated if you click inside one pane and then use the scroll wheel on a mouse that is not focused on the active pane. Click the Synchronous Scrolling button in the Window group to re-enable it. If the button is not visible, click the small arrow at the bottom of the Window group to expand the toolbar.
Side-by-Side View Is Not Available in Word Online
Word for the web (Word Online) does not include the View Side by Side command. To compare documents in a browser, open two browser tabs side by side using Windows Snap (Windows key + left or right arrow) and scroll each tab manually. This method does not support synchronous scrolling.
The Documents Appear Too Small to Read
When Word splits the screen, each pane is roughly half the width of your monitor. If your display resolution is 1366 x 768 or lower, the text may appear tiny. Use the Zoom slider in the lower-right corner of the Word window to increase the zoom level for each pane individually. Alternatively, reduce the font size in the document temporarily or use the Compare Documents tool under the Review tab to generate a difference report that fits in a single pane.
Side-by-Side View vs Compare Documents Tool
| Item | View Side by Side | Compare Documents (Review tab) |
|---|---|---|
| Purpose | Visual side-by-side reading | Automated difference detection |
| Output | Two separate windows on the same screen | One combined document with tracked changes |
| Synchronous scrolling | Yes, with Synchronous Scrolling button | Not applicable — single output document |
| Highlights changes | No — you find differences manually | Yes — marks insertions, deletions, formatting |
| Works with more than two files | Yes, with Arrange All | No — compares exactly two files |
| Available in Word Online | No | No |
For a quick visual check, use View Side by Side. For a thorough review that shows every change, use Compare Documents on the Review tab. The two methods serve different needs and can be used together.
With side-by-side view active, you can now compare two Word documents without switching windows or losing your place. Start by opening both files and clicking View Side by Side on the View tab. If you need a permanent record of changes, switch to the Compare Documents tool under the Review tab and choose the original and revised files. For documents that require frequent comparison, consider saving both versions in the same folder and naming them with version numbers so you can quickly open them together.