How do I see how much storage I am using?
Individual accounts
You can view how much storage you are using by going to drive.google.com/drive/quota.
On this page you will see how much storage you are using in both Google Drive and Gmail as well as your storage quota.
For example, you should see something like this image below. With this example, this person is using 20.54 GB of storage and they have a 25GB storage quota.
Non-person Accounts
Managers of non-person accounts can log into the non-person account directly to see the amount of storage being used by the account. Once logged in, you can go to drive.google.com/drive/quota to see the amount of storage being used.
Non-person account delegates can see the amount of storage being used by accessing the non-person Gmail account they have delegate access to. You will be able to see the amount of storage being used at the bottom of the non-person account inbox where it says "Using xxGB".
Google Shared Drives
Google Shared Drive Managers can see the amount of shared drive storage they are using by going to the shared drive and clicking the information or "i" icon in the top right. This will expand with details of the shared drive which will include the amount of storage being used by the drive.