ScrubsDownload

Guides › Mac folder guide · updated

What is purgeable space on a Mac, and how do you free it?

By Parsa Nasirimehr

It's space macOS has marked as reclaimable: copies of iCloud files it can download again, Time Machine's local snapshots, and some caches. Finder counts it as available, and macOS frees it by itself when an app needs the room, so you rarely need to do anything.

How big it gets

It changes all the time. Finder's Get Info on Macintosh HD counts it as available; df -h / shows only what is free right now, so the difference between the two is roughly the purgeable part.

What it is

iCloud DriveWith Optimize Mac Storage on in System Settings › your name › iCloud, files you haven't opened in a while can be removed from the Mac and downloaded again when you open them.
Local snapshotsWith Time Machine on, macOS keeps snapshots of the startup disk on the disk itself for about a day, and removes them first when space runs low.
CachesSome caches macOS deletes on its own when space runs low.
Why it confusesA file you delete may stay inside a snapshot, so deleting it frees nothing until the snapshot goes.

How to clear it

  1. Usually nothing: macOS frees it when space is needed.
  2. To free snapshots now, list them with tmutil listlocalsnapshots /, then ask macOS to free up to 50 GB of them: tmutil thinlocalsnapshots / 50000000000 4.
  3. Restart, which also clears temporary files and shrinks swap.

What you lose: Nothing you'd notice: iCloud files download again when you open them, and snapshots are only copies.

With Scrubs: Scrubs measures what is actually on the disk, not what macOS might free, so its total can differ from Finder's available space. Its map shows the real folders behind the space. Download Scrubs; scanning is free.

Related folders

sleepimage and swapWhat are sleepimage and the swap files on a Mac, and can you delete them?~/Library/CachesCan I delete the caches in ~/Library/Caches on my Mac?Photos libraryWhy is the Photos library taking up so much space on my Mac?

Paths and commands apply to macOS 15 and later. See also how to free up disk space on a Mac.

About the author: Parsa Nasirimehr is a mobile app developer who builds Scrubs, a disk map for the Mac. Spotted something wrong? Write to support@getscrubs.app.