Word limits the number of actions you can undo to 100 by default. This cap can be frustrating when you make many changes and need to revert further back than the limit allows. The undo limit is a fixed setting in the Windows Registry or macOS Terminal and cannot be changed through Word’s user interface. This article explains how to increase the undo history in Word on Windows by editing the Windows Registry and on macOS using the Terminal.
Key Takeaways: How to Increase Undo Levels in Word
- Windows Registry: HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Word\Options: Add a DWORD named UndoHistory with a decimal value up to 500 to raise the undo limit.
- macOS Terminal: defaults write com.microsoft.word UndoHistory -int 300: Run this command to set the undo history to a value up to 500.
- Maximum undo limit is 500: Word does not support setting the undo history above 500 actions regardless of the value you enter.
Why Word Has a 100-Action Undo Limit
Word stores your editing history in memory to enable undo and redo operations. Each action consumes a small amount of RAM. To prevent excessive memory usage, especially on older computers with limited RAM, Microsoft set a default cap of 100 actions. This limit was established years ago when computers had far less memory than they do today.
The undo limit applies to actions within a single Word session. Closing and reopening a document resets the undo history. The limit is stored in the Windows Registry on Windows and in the user defaults system on macOS. Word reads this value at startup and does not allow dynamic changes during a session.
Increasing the undo history to the maximum of 500 actions works on Word 2013, 2016, 2019, 2021, and Word for Microsoft 365. The same registry key and Terminal command apply to all these versions.
Steps to Increase Undo History in Word on Windows
Editing the Windows Registry is the only method to change the undo limit in Word on Windows. Follow these steps carefully. A mistake in the Registry can cause system instability. Back up the Registry before making changes.
- Open Registry Editor
Press Windows + R, type regedit, and press Enter. Click Yes if User Account Control prompts you. - Navigate to the Word Options key
In Registry Editor, go to:HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Word\Options
The version number 16.0 applies to Word 2016, 2019, 2021, and Microsoft 365. For Word 2013, use 15.0 instead of 16.0. - Create a new DWORD value
Right-click the Options folder in the left pane. Select New > DWORD (32-bit) Value. Name the new value UndoHistory exactly as shown, including capital letters. - Set the undo history value
Double-click the UndoHistory value. Select Decimal as the base. Enter a number between 100 and 500. 500 is the maximum supported value. Click OK. - Close Registry Editor and restart Word
Exit Registry Editor. Close all open Word documents and then reopen Word. The new undo limit takes effect immediately.
Increase Undo History in Word on macOS
On macOS, you use the Terminal application to modify the undo limit. The command uses the defaults system.
- Open Terminal
Go to Applications > Utilities > Terminal. Alternatively, search for Terminal using Spotlight. - Run the defaults command
Type or paste the following command and press Enter:defaults write com.microsoft.word UndoHistory -int 500
Replace 500 with any number between 100 and 500. - Restart Word
Quit Word completely using Command+Q. Reopen Word for the change to take effect.
Common Issues After Changing the Undo Limit
Word Does Not Save the New Undo History Value
If Word reverts to the default 100-action limit after you close and reopen the program, the Registry key or defaults value was not created correctly. On Windows, verify that the UndoHistory DWORD exists under the correct path and that the value is set to Decimal. On macOS, run defaults read com.microsoft.word UndoHistory in Terminal to confirm the value was saved.
Word Performance Slows Down With a Higher Undo Limit
A higher undo limit uses more RAM, especially if you edit large documents with many images, tables, or tracked changes. If Word becomes sluggish or crashes, reduce the undo limit to 300 or 200. The default 100 is still optimal for most users on systems with 4 GB of RAM or less.
Undo History Resets After Saving and Closing a Document
This is normal behavior. Word clears the undo history when you close a document, regardless of the undo limit setting. The undo limit only controls how many actions you can undo within a single editing session. To preserve undo history across sessions, use the Save As command to create a versioned copy of your document instead of relying on undo.
Undo Limit Default vs Maximum Comparison
| Item | Default Limit (100) | Maximum Limit (500) |
|---|---|---|
| Number of undoable actions | 100 | 500 |
| RAM usage per session | Low (approx 2-5 MB) | Higher (approx 10-25 MB depending on document size) |
| Configuration method | None (built-in) | Windows Registry or macOS Terminal |
| Supported Word versions | All versions | Word 2013 and later |
| Persistence after restart | Always active | Requires correct Registry key or defaults value |
You can now increase the undo history in Word up to 500 actions by editing the Windows Registry or macOS Terminal. Test the new limit by making a series of edits and pressing Ctrl+Z or Command+Z repeatedly. If you experience performance issues, lower the value to 300. For a quick way to revert to the default, delete the UndoHistory DWORD on Windows or run defaults delete com.microsoft.word UndoHistory on macOS.