Do Outlook PST Files Have a Size Limit?

Keep your Outlook PST archive folder size small for best performance

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All Microsoft Outlook versions use PST files to store email, contacts, calendar data and other Outlook data. Over time, these files grow in size, and as they do, Outlook performance takes a hit. Keeping the PST file sizes small, either through deleting old information or archiving it, keeps Outlook performing at its snappy best.

There are two kinds and sizes of PST files.

PST Size Limits for Outlook 2003, 2007, 2010, 2013 and 2016

Outlook 2003, 2007, 2010, 2013 and 2016 use a PST file format capable of storing Unicode data, a standard that can represent most alphabets on computers, These PST files have no size limit, but a practical limit of 20GB to 50GB is recommended.

For performance and stability reasons, it is not recommended to go beyond 20GB in Outlook 2003 and Outlook 2007 PST files.

PST Size Limits for Outlook 97 through 2002

Outlook versions 97 to 2002 use a PST file format restricted to U.S. English. Foreign-language characters need to be encoded. PST files have a hard-wired limit of 2GB that cannot be increased.

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

How to Archive PST Messages in Outlook 2007

To archive PST Messages or other data in Outlook 2007: 

  1. Choose File > Data File Management from the Outlook menu.
  2. Click Add
  3. Select the desired format. Unless you think you may need to access the archive in a version of Outlook 2002 or older, select Office Outlook Personal Folders File (.pst).
  4. Click OK.
  5. Enter a file name. Monthly or yearly archives make sense, but you can choose a name that works best for you. However, plan to keep the file small—under 2GB. Larger files are not as efficient.
  6. Click OK.
  7. Type the archive PST file name under Name. Optionally, protect the file with a password.
  8. Click OK and Close

Now that you have created an archive PST file, you can drag and drop entire folders to the root folder that appears under Mail Folders. You can also right-click on the root folder named after your archive PST, select New Folder from the menu, give the folder a name, select Mail and Post Items (or another appropriate category) and click OK.  Then, drag and drop individual emails or groups of emails to the folder.

How to Archive PST Messages in Outlook 2016

  1. Click File.
  2. In the Info category, click Account Settings.
  3. Select Account Settings... and go to the Data File tab.
  4. Click Add.
  5. Type the name of the archive under File name.
  6. Select the desired format under Save as type. Usually, Outlook Data File is the best choice.
  7. Optionally, protect the file with a password.
  8. Click OK.
  9. Click Close.

Move old messages to the Archive PST file in the same manner as for Outlook 2007.

You may never need to access your archive files, but it isn't difficult to restore an Outlook PST archive.