When a mailbox is close to its maximum capacity, individuals will receive emails and in-app messages. If the mailbox exceeds its capacity, you won't be able to send or receive messages. Check the current size of your mailbox by following the steps below.

Outlook Web Access

In Outlook Web Access (OWA)

  • Log in
  • Click the Gear icon at the top right
  • Click General, then Storage.

You’ll see your total free storage and a breakdown of your usage by folder and type.

OWA Storage

Outlook for Windows

  1. In the Mail view, click your account.

Outlook account

2. Click Folder > Folder Properties.

Ribbon folder properties

3. Click Folder Size at the bottom of the pane.

Folder properties

4. You’ll see that the size of the mailbox and each subfolder is indicated in kilobytes (KB).

Folder size

To find the size in megabytes, move the decimal point over three places to the left.

For example, 4742 KB is roughly 4.7 MB. For the exact figure, divide the KB value by 1024.