If macOS Disk Utility shows a large swath of "Purgeable" storage and you need that space back right now, the usual advice — "just wait, macOS will handle it" — is not helpful. This guide explains exactly what purgeable space is, why macOS holds onto it longer than you expect, and three concrete methods to force your Mac to clear purgeable space immediately, ranked by how fast they actually work.
What Purgeable Space Actually Is
Purgeable space is disk capacity that macOS has earmarked but has not yet released. It falls into two main buckets:
- APFS local snapshots. Time Machine (and, on Apple Silicon, system restore) creates point-in-time snapshots stored locally on your APFS volume. Each snapshot can consume several gigabytes. macOS is supposed to thin them automatically when space runs low, but "low" is defined conservatively.
- iCloud-optimized files. Documents, Desktop files, and Photos that have been uploaded to iCloud but whose local copy macOS is keeping as a cache. If storage pressure rises enough, macOS evicts these to the cloud and reclaims the space.
Neither category is empty, junk data. Deleting snapshots means you lose the ability to roll back to that point in time. Evicting iCloud files means the next time you open them they must re-download. Both operations are safe for most users, but you should know what you are giving up.
Method 1: Create Artificial Disk Pressure (Fastest)
macOS will not release purgeable space until it believes storage is critically low. The quickest way to trigger that logic is to create a large temporary file that forces the operating system to start clearing its own caches and snapshots to make room, then delete the file.
- Open Terminal (
Applications > Utilities > Terminal). - Run the following command. Replace
20gwith however many gigabytes you want to reclaim — start conservatively:
mkfile -n 20g ~/Desktop/pressure.tmp- Watch Activity Monitor (or Disk Utility) — purgeable space will start shrinking as macOS responds to the pressure. This usually takes 30–90 seconds.
- Once purgeable space has dropped, delete the file:
rm ~/Desktop/pressure.tmpHonest caveat: This method works reliably on macOS Monterey through Sequoia (12–15) and should continue working on macOS 26 Tahoe. However, if your volume has very little free space to begin with, mkfile will simply fail because there is nowhere to write the file. In that case, skip to Method 2.
Method 2: Manually Thin or Delete APFS Snapshots
If local Time Machine snapshots are the dominant source of purgeable space, you can list and delete them directly.
List all local snapshots
tmutil listlocalsnapshots /You will see output like:
com.apple.TimeMachine.2026-05-28-143012
com.apple.TimeMachine.2026-05-30-091500
com.apple.TimeMachine.2026-06-01-224015Delete a specific snapshot
tmutil deletelocalsnapshots 2026-05-28-143012Delete all local snapshots at once
for snap in $(tmutil listlocalsnapshotdates / | grep "-"); do tmutil deletelocalsnapshots "$snap"; doneRisk level: Low-to-medium. Deleting snapshots permanently removes those restore points. If you have a recent external Time Machine backup (or rely only on iCloud), losing local snapshots is low risk. If local snapshots are your only backup, delete them only after confirming your external backup is current.
Method 3: Boot into Safe Mode
Safe Mode forces macOS to perform several cleanup tasks at startup, including purging some caches and triggering snapshot thinning. It is the slowest of the three methods but useful if the disk-pressure trick fails or you want a clean slate.
Apple Silicon Macs
- Shut down completely.
- Press and hold the power button until "Loading startup options" appears.
- Select your startup disk, then hold Shift and click Continue in Safe Mode.
- Log in, wait for the desktop to load fully, then restart normally.
Intel Macs
- Restart and immediately hold Shift after the startup chime.
- Release Shift when the login window appears.
- Log in, then restart normally.
Safe Mode is the most conservative approach. It does not delete anything you would miss; it only releases caches macOS itself owns. The downside is boot time: Safe Mode startup takes two to three times longer than normal.
Method Comparison
| Method | Typical time to reclaim space | What is removed | Risk |
|---|---|---|---|
Disk pressure (mkfile) |
30–90 seconds | Snapshots + iCloud caches, as chosen by macOS | Low (macOS decides what to evict) |
| Manual snapshot deletion | Seconds per snapshot | Specific APFS snapshots you choose | Low-medium (lose restore points) |
| Safe Mode boot | 5–15 minutes (boot cycle) | System caches, some snapshot thinning | Very low |
| Crumb one-click Clean | Seconds | Caches, logs, temp files, purgeable reclaim | Low (shows what will be removed before acting) |
What About the purge Command?
You may have seen advice to run sudo purge in Terminal. That command flushes the RAM disk cache, not storage. It will not reduce the purgeable figure you see in Disk Utility and will make your Mac feel sluggish for a minute or two while it rebuilds the cache. Skip it for this use case.
Using Crumb to Reclaim Purgeable Space in One Click
If you would rather not touch Terminal, Crumb handles this automatically. Its one-click Clean operation sweeps system caches, user caches, logs, and temporary files, and the reclaim of purgeable storage is triggered as part of that process — the same way the disk-pressure method works, but without you having to manage the temp file yourself. Crumb shows you exactly how much it will remove before it does anything, so there are no surprises.
For a deeper pass, Crumb's Visualize tab surfaces the largest items and the full-Mac audit so you can see at a glance whether APFS snapshots, a bloated ~/Library/Caches, or a forgotten app's support folder is the real culprit. You can download Crumb and run your first cleanup for free.
After You Reclaim the Space
Once purgeable space has been cleared, Disk Utility should show a lower "Used" figure. A few things to keep in mind going forward:
- macOS will start accumulating new snapshots within hours of a clean state — this is normal and healthy behaviour.
- If your disk is consistently over 80% full, snapshots and iCloud caches will cycle more aggressively and you may notice performance degradation. Consider whether you need a larger drive or whether there are large files (old VM images, media exports, Xcode device caches in
~/Library/Developer/CoreSimulator) that can be moved or deleted permanently. - Cleaning caches is permanent and generally safe, but some apps will rebuild their caches from scratch on next launch, causing a brief slowdown. That is expected.
The disk-pressure trick with mkfile remains the fastest single technique to force purgeable space to clear on any APFS Mac. Pair it with manual snapshot management if you want precise control, or let a tool like Crumb handle the whole process automatically. Either way, you now have real options instead of waiting for macOS to decide it is ready.