What is purgeable space on Mac, and how to free it
In short
Purgeable is space macOS counts as available because it can free it when needed: local Time Machine snapshots, iCloud files already in the cloud and some caches. Usually that's fine, but installers don't always wait for it. Restarting or deleting local snapshots frees it right away.
What counts as purgeable
- Local Time Machine snapshots: copies of recent changes kept for about 24 hours, so you can recover a file even without the backup drive.
- iCloud files already uploaded, when Optimize Mac Storage is on: macOS can remove the local copy and keep a placeholder.
- Some caches macOS manages itself.
Where to see it
Select your disk in Finder and press ⌘I (Get Info): Available includes purgeable space. Disk Utility shows the purgeable figure apart. That's why two tools can disagree on how much free space you have.
When it's a problem
A macOS update, a big copy or an app installer may check free space without counting purgeable space, or without waiting for macOS to release it. You see “40 GB available” and still get “not enough space”.
How to free it now
- Restart the Mac. It often releases snapshots and caches.
- Delete local snapshots (your backups on the external drive aren't touched):
tmutil listlocalsnapshots / sudo tmutil deletelocalsnapshots / - Let a Time Machine backup finish, if you use one: old snapshots are removed after it.
Then, real space
Purgeable space comes back to you; it isn't lost. If you still need room, the next step is what recreates itself: caches, build data and installers you already used.
DiskSpace AI does this for you
It analyzes your Mac in minutes, tells you what each folder is and only selects what recreates itself. Your files are kept 7 days in case you change your mind. Free during the beta.
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