If your Outlook data file is reaching its storage limit, you can increase its capacity by modifying certain values in the Windows Registry.

Steps to Increase the PST File Size

1. Open Run

Press: Windows + R

2. Open the Registry Editor

Type: regedit and press Enter.

3. Go to the Outlook PST Folder

Navigate to the following path: HKEY_CURRENT_USER/Software/Microsoft/Office/Outlook/PST

Use the corresponding version:

• 15.0: Outlook 2013 and earlier.
• 16.0: Outlook 2016 and later.

4. Locate the Following Values

• MaxLargeFileSize
• WarnLargeFileSize

If either of these values does not exist, create it by selecting: New → DWORD (32-bit) Value

5. Modify the Values

For MaxLargeFileSize:

• Base: Decimal
• Value data: 102400

For WarnLargeFileSize:

• Base: Decimal
• Value data: 102000

6. Restart Outlook

Close the Registry Editor and reopen Outlook for the changes to take effect.

Important: Before making any changes to the Windows Registry, we recommend creating a backup copy of your PST file.