What counts as purgeable
- Local Time Machine snapshots: hourly snapshots of your disk, kept about 24 hours. They also hold onto files you've just deleted.
- Optimised iCloud files: local copies of iCloud Drive and Photos items that macOS can re-download later.
- Some caches that macOS knows can be rebuilt.
See how much you have
Select your disk in Finder and press ⌘I: Available includes purgeable space in brackets on recent macOS. Disk Utility also shows a Purgeable figure. Compare with df -h /, which counts it as used.
Free snapshot space now
The first command lists snapshots by date. The second asks macOS to thin as many as it can at urgency 4, the highest. The third removes one snapshot: replace the date with one from the list.
tmutil listlocalsnapshots /tmutil thinlocalsnapshots / 999999999999 4tmutil deletelocalsnapshots 2026-11-02-093000These only touch local snapshots on your Mac. Backups on your Time Machine drive stay as they are.
Free iCloud space now
Turn on System Settings › [your name] › iCloud › iCloud Drive › Optimise Mac Storage, then right-click big iCloud Drive folders in Finder › Remove Download. The files stay in iCloud and download again when you open them.
Check that it worked
Run df -h / again. Broom's Overview and menu bar item show free space as macOS reports it, so you'll see the change there too, and a rescan shows what's still big.
Questions
Is it safe to delete purgeable space?
Yes. Purgeable items are, by definition, things macOS can recreate or re-download. Thinning local snapshots doesn't touch your real backups.
Why won't macOS free purgeable space for an update?
Some installers check free space before macOS gets a chance to purge. Thinning snapshots by hand first usually fixes it.
How do I stop local snapshots?
They're tied to Time Machine. Turning Time Machine's automatic backups off stops new ones; macOS also thins them by itself when space runs low.