Gmail storage is full even after deleting emails, how can I free space without upgrading?

It's likely that your Google account storage (15 GB free) is being used by more than just Gmail when it says "storage is full," even after you've deleted emails. Go to Google One Storage first to see what's taking up room.

To get rid of large attachments, use filters in Gmail like has:attachment larger:10M and delete them forever from the Trash.

Next, look through Google Drive's "Storage" area for old or large files. Delete the ones you don't need, then empty Drive's Trash.

If you want to get rid of blurry or big photos in Google Photos, open the Storage Management tool and empty the Trash.

Getting rid of these three things often makes a lot of room available without having to upgrade.

These are key solutions that we can offer. If you have more, please share.