How to Change the Size Limit for Outlook PST Files

As we all know, there is a default size limit for Outlook PST files. In this article, we will introduce a quick method, which enables you to change the size limit as per your needs.

Unlike the previous versions which use the old ANSI format for PST files, Outlook 2003 and newer versions have begun to use Unicode format. The new format has supported much larger data files. In Outlook 2003 and 2007 the maximum size of Unicode PST files are 20 GB. And since Outlook 2010, the size has been raised to 50 GB. Actually the size is entirely enough for most users. But if you still would like to increase it, you can use the following methods.

Change the Size Limit for PST Files in Unicode Format

  1. At the very outset, you should close Outlook thoroughly.
  2. Then go to “Start Menu”, and type “regedit” in the search box.Search Regedit
  3. And press “Enter” key button to start Registry Editor. Here you may receive a Windows prompt, which aims to confirm the permission for Registry Editor. You can click “Yes” button.
  4. Next in the Registry Editor, you need to browse to the following registry path: HKEY_CURRENT_USER\Software\Microsoft\Office\<version>\Outlook\PST

Note: In regard to “<version>”, Outlook 2003 refers to “11.0”, Outlook 2007 to “12.0”, Outlook 2010 to “14.0”, Outlook 2013 to “15.0” and Outlook 2016 refers to “16.0”.

  1. After that, right click the blank space in the right pane and choose “New” > “DWORD Value” from the context menu.Create a New DWORD Value
  2. Rename the new value to “MaxLargeFileSize”. This value sets the maximum size of a Unicode PST file. Double click it. In the popup “Edit DWORD Value” dialog box, change “Base” to “Decimal” and then specify the concrete value in MB. For example, in Outlook 2010, if you want to increase the maximum size from the default 50 GB to 100 GB, you should enter “102400”.Edit MaxLargeFileSize Value Data
  3. After that, create another DWORD value called “WarnLargeFileSize”. It sets the warning level for Unicode PST file. Thereby, when the PST file reaches the specified size, you will receive an Outlook warning that the file is full. Double click the new value and input the value data in “Decimal”, using MB.

Note: You had better keep at least 5 % difference between “MaxLargeFileSize” and “WarnLargeFileSize”.Edit WarnLargeFileSize Value Data

  1. Finally close Registry Editor and restart Outlook to activate the changes.

Extra Tip: For the PST files in old ANSI format, you can change the maximum size limits by changing “MaxFileSize” and “WarnFileSize”. The steps are equal to the above.

Restore the Default Size Limit

If one day, you wish to reset the default size limit, you can follow the steps below:

  1. At first, reduce the file until its size is well below the default size limit – 20 GB in Outlook 2003/2007, 50 Gb in Outlook 2010 and newer, 1.8 GB for ANSI PST files.
  2. Then go to Registry Editor and delete the two registry keys.
  3. Lastly restart Outlook. The change will take effect automatically.

Keep Outlook PST Files in Appropriate Size

As we all know, Outlook is very susceptible to corruption, especially when it gets oversized. Therefore, we should always keep tabs on the file size in case of any tragedy. For example, you can split the large file into several small ones. Of course, keeping a remarkable repair tool nearby is also a matter of necessity, such as DataNumen Outlook Repair. It will repair Outlook file corruption in time when PST file gets corrupted due to oversize.

Author Introduction:

Shirley Zhang is a data recovery expert in DataNumen, Inc., which is the world leader in data recovery technologies, including repair mdf database corruption and outlook repair software products. For more information visit

Comments are closed.