If you want to see how much space your company's data is taking in Microsoft 365, sign into the Microsoft Admin Center.
Select Reports and the service you want to view:
- Exchange: Click Mailbox usage. You will see the size of your Exchange data under Storage / Amount of storage used.
- OneDrive: Click Usage to see the OneDrive data size under Storage.
- SharePoint: Click Site usage to see the SharePoint data size under Storage.
To get the total storage usage, you need to add up the storage sizes per service. Unfortunately the total storage size is not displayed in Microsoft Admin Center.