How to Check Your Outlook Folders & Sizes

Reduce your Outlook folder sizes by finding the largest emails

Woman using laptop on beach
Jamie Grill/Getty Images

Find out how big your email folders have grown in Outlook—and take action if they are too big for their own good.

Is Your Outlook Slow and Unwieldy Lately?

Has handling email in Outlook become slow and unwieldy, or is your hard disk shrinking and you suspect the ten thousand emails with thousands of attachments might be involved?

Which folder is to be blamed, though, and where do the big emails hide?

Fortunately, Outlook comes with a small tool that lets you find out exactly how much space each folder occupies on disk.

Check Your Outlook Folders' Sizes

To see the size of your folders in Outlook:

  1. Open Outlook. Right-click the folder where you want to check the size and select Data File Properties.

    Screenshot of Data File Properties in Outlook
  2. In the folder properties window, select the Folder Size button.

    Screenshot of the Folder Size button in the Folder Properties window
  3. The Folder Size window will show you the entire size of the folder in kilobytes, as well as a breakdown of all of the subfolder sizes.

    Screenshot of folder size window in Outlook
  4. By checking the size of each folder and subfolder, you can identify which account is using up the most space, as well as the subfolders that may contain files that are too large.

Check Your Folders' Sizes in Outlook 2003 and 2007

To see the size of your Outlook 2003 or Outlook 2007 folders:

  1. Select Tools > Mailbox Cleanup from the menu.
  2. Select View Mailbox Size.
  3. Select Close (two times) to close the mailbox size view again.

Reduce the Size of an Outlook File by Archiving Mail

Archiving old or less frequently accessed messages is an easy way to keep all your Outlook folder and files' sizes manageable. Outlook can even do the archiving automatically.

Find the Biggest Emails in Your Outlook Folders

To have Outlook gather all the biggest emails found across all your folders:

  1. Select the Search Current Mailbox field in your Outlook inbox. You can also press Ctrl-E. Make sure the Search ribbon is visible and expanded.

    Screenshot of the search ribbon in Outlook
  2. Select Search Tools in the Search ribbon's Options section. Select Advanced Find from the menu that has appeared.

    Screenshot of Search Tools in Outlook
  3. Make sure Messages is selected under Look.

    Screenshot of Advanced Find in Outlook
  4. To search more folders than the inbox (or whichever folder is currently open in Outlook's main window):

    1. Select Browse.
    2. Make sure all the folders you want to search are checked under Folders.
      1. Typically, check the root folder for the account or PST files you want to include in your search and make sure Search subfolders is checked as well.
      2. Unfortunately, Outlook will not let you search across accounts and PST files.
    3. Select OK.
    Screenshot of selecting folders in Outlook
  5. Open the More Choices tab. Make sure greater than is selected under Size (kilobytes). Enter something like 5000 (~5 MB) under Size (kilobytes). You can choose a bigger or smaller number, of course, to have more or fewer results returned. Select Find Now.

    Screenshot of Advanced Find in Outlook
  6. Now, double-click any item to open it and deal with it as you see fit. You can also click the red x () in search results to delete any message right away.