Gmail, Drive and Photos all eat the same free 15 GB. Nine steps clear real space today, and the last one is the only one you cannot undo.
Open one.google.com/storage. The storage manager splits your usage across Photos, Drive and Gmail, so you stop guessing which app is the real problem.
Backed-up items sit in the Google Photos bin for 60 days before they go. Gmail counts Spam and Trash too. Clearing both is the fastest space you will reclaim.
In Google Photos, tap Manage storage. It surfaces blurry shots, screenshots and large videos already grouped for review, so deleting takes a couple of taps.
A single 4K clip can outweigh hundreds of stills. Delete a handful of long videos before you spend an hour culling photos one at a time.
In the Gmail search box type larger:10M has:attachment. Add older_than:1y to catch the ancient ones. A decade of attachments is usually gigabytes.
Go to drive.google.com/drive/quota. It lists only the files that count against your quota, biggest first, including ones buried in folders you forgot.
A file someone shared with you counts against the owner's quota, not yours. Deleting it frees nothing on your account, so spend the effort elsewhere.
Google counts Android device backups, which cover texts, call logs, settings and app data, plus WhatsApp backups. Phones you no longer own can still be in there.
On a computer, Manage storage offers Convert existing photos and videos to Storage saver. It shrinks every original you have uploaded, and the originals are gone.
Bins, big videos and old attachments alone give most accounts gigabytes back. If you still run out after that, compare where the extra room is cheapest.