How to Compact a PST File in Outlook

Compress those PST files in Outlook to save space

Files tied up with twine with tags dangling.

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When you delete an email in Outlook, it goes to the trash, i.e. the Deleted Items folder. When you empty the Deleted Items folder, all the deleted messages disappear—but they are still in your PST file.

While Outlook periodically reclaims that wasted space in the background, you can manually initiate the process, too. This makes good sense after you have emptied the Deleted Items folder for the first time after a lot of spam, or if you have just moved a year's worth of mail to your archive PST, for example.

Instructions in this article apply to Outlook 2016, 2013, 2010, and 2007.

Compact a PST File to Reduce Its Size in Outlook 2016, 2013, and 2010

To manually start reclaiming wasted space in an Outlook PST file:

  1. Go to File > Account Settings > Account Settings.

    Account settings in Outlook.
  2. Select Data Files.

    Selecting the data files option within account settings in Outlook.
  3. Select the data file you want to compact.

    Selecting a PST file to view settings in Outlook.
  4. Select Settings.

    Viewing the Outlook data file settings in Outlook.
  5. Select Compact Now. A progress bar should open showing the compact status.

    A PST file is compacting in Outlook.
  6. Select OK.

  7. Select Close.

Compact a PST File to Reduce Its Size in Outlook 2007

To manually start reclaiming wasted space in an Outlook PST file:

  1. Select File > Data File Management.

  2. Select the data file you want to compact.

  3. Select Settings.

  4. Select Compact Now.