Do Outlook PST Files Have a Size Limit?

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All Outlook versions use PST (Personal Folder) files to store emails, contacts, calendar data and more. There are two kinds of PST files, however.

Outlook 2003 and later use a PST file format capable of storing Unicode (a standard that can represent most alphabets on computers) data that has no theoretical size limit but a practical limit of 20-50 GB.

Outlook versions before that (97 to 2002) use a PST file format restricted to U.S. English (foreign-language characters need to be encoded in that format) that has a hard-wired limit of 2 GB.

Outlook PST File Size Limits

Here, again, are the two formats, with their limits and typical use:

Outlook 97-2002 Personal Folders File (PST)

Office Outlook Personal Folders File (PST)

  • Used by:
    • Outlook 2003 (with the exceptions above)
    • Outlook 2007–Outlook 2016
  • Size limit:
    • Configurable; 50 GB by default (20 GB in Outlook 2003 and Outlook 2007)
    • For performance and stability reasons, it is not recommended to increase the limit beyond 20 GB in Outlook 2003 and Outlook 2007.

As your PST file approaches the limit or the suggested maximum size (check the size via the ​Total size given in the Folder Size dialog), you can move old messages to a separate archive PST file — or delete them, of course.

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