How to Check Your Outlook Folders & Sizes

Reduce your Outlook folder sizes by finding the largest emails

Has handling email in Outlook become slow and unwieldy, is your hard disk shrinking, or are you about to reach your Inbox size limit and you suspect the emails with attachments might be involved? Outlook comes with a tool that shows how much space each folder occupies. Find out how big your email folders have grown in Outlook and take action if they are too big.

Instructions in this article apply to Outlook 2019, 2016, 2013, 2007; and Outlook for Office 365.

Check Your Outlook Folders' Sizes

To see the size of your folders in Outlook:

  1. Right-click the folder where you want to check the size and select Data File Properties. In Outlook 2019, select Properties.

    Screenshot of Data File Properties in Outlook
  2. In the Properties dialog box, select Folder Size.

    Screenshot of the Folder Size button in the Folder Properties window
  3. The Folder Size dialog box shows the 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 2007

To see the size of your Outlook 2007 folders:

  1. Select Tools > Mailbox Cleanup.
  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 text box. Or, press Ctrl+E.

    Screenshot of the search ribbon in Outlook
  2. Go to the Search tab.

  3. In the Options group, select Search Tools > Advanced Find.

    Screenshot of Search Tools in Outlook
  4. In the Advanced Find dialog box, select the Look dropdown arrow and choose Messages.

    Screenshot of Advanced Find in Outlook
  5. To search more folders than the inbox (or whichever folder is currently open in Outlook's main window), select Browse. Select the check box next to the folders you want to search and select the Search subfolders check box. Select OK.

    Screenshot of selecting folders in Outlook
  6. In the Advanced Find dialog box, go to the More Choices tab.

  7. Select the Size (kilobytes) dropdown arrow, choose greater than, then enter a size (such as 5000 for folders greater the 5 MB).

    Screenshot of Advanced Find in Outlook
  8. Select Find Now.

  9. Double-click a message to open it and deal with it as you see fit. Or, select Delete in the search results to delete any message right away.