How to Increase the PST File Size in Outlook Using the Registry Editor

Managing PST (Personal Storage Table) files in Microsoft Outlook is crucial for users who deal with extensive emails and attachments. By default, the maximum size of a PST file is limited to 47.5 GB, but in certain cases, you may need to increase this limit. Here’s a step-by-step guide to modify the PST file size limit using the Windows Registry Editor.

Step-by-Step Guide to Modify PST File Size Limit

1. Open the Registry Editor

   • Press Win + R to open the Run dialog box.
   • Type regedit and press Enter.
   • Click OK to proceed when prompted for administrative permissions.

2. Navigate to the PST Registry Key

   • In the Registry Editor, go to:
     HKEY_CURRENT_USER\Software\Microsoft\Office\<version_number>\Outlook\PST
   • Replace <version_number> with your version of Office (e.g., 16.0 for Office 2016).

3. Modify the MaxLargeFileSize Value

   • Select the PST key on the left panel.
   • On the right panel, locate and right-click MaxLargeFileSize.
   • Select Modify.

4. Set the Desired File Size Limit

   • Choose Decimal as the base.
   • Enter the desired size limit in megabytes (e.g., 51200 for 50 GB).
   • Click OK to save the changes.

5. Adjust the WarnLargeFileSize Value (Optional)

   • Similarly, modify the WarnLargeFileSize value to set a warning threshold for PST file size.
   • Ensure there is at least a 5% difference between MaxLargeFileSize and WarnLargeFileSize to avoid unexpected errors.

6. Restart Outlook

   • Close and reopen Microsoft Outlook for the changes to take effect.

Important Considerations

• Default Size: The default maximum PST file size is 47.5 GB (48,640 MB).
• Recommended Limit: Avoid setting limits beyond 100 GB to maintain system performance and file stability.
• Backup First: Always back up your registry before making changes to prevent potential issues.