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 Deleted Items folder. When you empty the Deleted Items folder, the deleted messages are still in your PST file. Outlook periodically reclaims that space, but you can manually initiate the process. To save space, compact the PST file after you empty 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 2019, 2016, 2013, 2010, 2007; and Outlook for Office 365.

Compact a PST File to Reduce Its Size in Outlook 2019, 2016, 2013, and 2010

To manually reclaim space in an Outlook PST file:

  1. Go to the File tab and select Info.

  2. Select Account Settings > Account Settings.

    Account settings in Outlook.
  3. In the Account Settings dialog box, select the Data Files tab.

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

  5. Select Settings.

    Selecting a PST file to view settings in Outlook.
  6. Select Compact Now.

    Viewing the Outlook data file settings in Outlook.
  7. A progress bar shows the compact status.

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

  9. Select Close.

Compact a PST File to Reduce Its Size in Outlook 2007

To manually reclaim 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.