Mac storage basics · Checking your storage
What do the recommendations in macOS Storage settings actually do?
Short answer: Store in iCloud keeps Desktop and Documents online-only when space is low, Optimise Storage removes watched Apple TV videos, and Empty Trash Automatically deletes items left in the Trash over 30 days.
macOS offers up to three switches in System Settings → General → Storage:
- Store in iCloud — keeps Desktop and Documents (and optionally photos and messages) in iCloud, leaving older, unopened files online-only on the Mac.
- Optimise Storage — removes Apple TV movies and shows you've already watched from the Mac (you can download them again).
- Empty Trash Automatically — permanently deletes items that have been in the Trash for more than 30 days.
None of them deletes your own documents outright, but Store in iCloud uses your iCloud storage plan and needs a connection to open older files, and the Trash option is permanent after 30 days.
Storage Studio can do the online-only part across iCloud and other cloud apps from Optimise Cloud Storage Locally. See iCloud questions.