What is the maximum size limit in GB of a Microsoft Office Outlook 2003 PST file?

2 Answers 2


It's actually configurable by registry. The default size limit is 2GB for Outlook 2003. If you are using the Large File Format, the limit is 20 GB.

For more information about configuring it, read here.

  • 1
    So if I haven't done any registry changes, but I have a PST file that's 6.6 Gb, that could explain why I have problems with Outlook failing to retrieve the data file on a consistent basis, or running slowly?
    – milkmood
    May 23, 2011 at 16:00
  • @milk Well if it's 6.6Gb, then it's 825MB, well under the 2GB size limit, so you should be okay. (Yes, I'm aware you probably meant GB, but I felt the need to illustrate the importance of using correct units).
    – squircle
    May 23, 2011 at 16:09
  • You should probably archive out the old emails etc into an separate PST file. Keeping just the recent emails in the main PST will keep its size down (might have to run it through the compaction process once), which in turn should help performance, especially on older PCs with slower processors/less RAM.
    – Spectre
    May 23, 2011 at 16:21
  • @squircle - Of course I meant GIGABYTES. Who uses gigabits except when referring to network speed. Anyway...I did an archive of anything older than 9 months, and the new archive PST is 2.2 GIGABYTES but the working PST is still 6.6 GIGABYTES. How does that happen?
    – milkmood
    May 23, 2011 at 18:10
  • @milkmood They're both perfectly valid units of measurement. As long as you're aware of that, my work is done!
    – squircle
    May 23, 2011 at 18:52

In Outlook 2002 and its earlier versions, .pst file is in ANSI format and its size limit is 2 GB. In Outlook 2003 and 2007, .pst files are in Unicode format and by default the limit is configured as 20 GB.

For more information visit - http://support.microsoft.com/kb/830336

Regards Jane

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