Mac storage basics · When the disk is full
Why does my Mac's storage keep filling up by itself?
Short answer: Typically local snapshots, a runaway app cache or log, cloud apps downloading files, device backups or updates, or swap. A space-watching tool helps catch which.
Usually one of these:
- Local snapshots holding space after you delete or change big files.
- An app writing caches or logs out of control.
- Cloud apps downloading files from iCloud, Dropbox or Google Drive.
- Device backups or updates downloading in the background.
- Swap growing under heavy memory use.
The hard part is catching it in the act. Storage Studio keeps a light watch on free space, tells you which app the space went to when it can identify one, and its Where did my space go? view breaks down any period you choose. See freeing up space.