Mac storage full? How to shrink System Data and free up space

1. See what's using space

Open System Settings › General › Storage. The bar shows each category, and the recommendations below it (Store in iCloud, Optimize Storage, Empty Trash Automatically) are safe, quick wins. Click ⓘ next to a category to review and delete large items.

2. What is System Data?

System Data is everything that doesn't fit another category: caches, logs, swap files, local Time Machine snapshots, developer tools and app support files. Much of it is temporary, and macOS removes it automatically when space gets tight.

Some of it is purgeable, which is why different apps report different free space.

3. Quick, safe wins

• Restart. This clears swap files and temporary data, and often frees several gigabytes of System Data at once.
• Empty the Trash, then check Downloads for old installers and disk images.
• Delete old iPhone and iPad backups under Storage › iOS Files.
• Remove apps you don't use under Storage › Applications, sorted by size.

4. If you use Xcode or Docker

• Xcode keeps old simulators and build data. Remove unused simulator runtimes in Xcode's settings under Platforms (or Components), and delete ~/Library/Developer/Xcode/DerivedData (Xcode rebuilds it as needed).
• Docker's disk image grows over time. Remove unused images and containers with docker system prune, after checking nothing you need will be removed.
• node_modules folders in old projects add up quickly; delete them in projects you aren't working on.

5. Local Time Machine snapshots

When Time Machine is on, macOS keeps local snapshots on your startup disk and deletes them automatically when space is needed. To see them, run tmutil listlocalsnapshots / in Terminal. They usually disappear within a day or so without any action.

How much free space should you keep?

Aim for at least 10–15% of your disk free, and more if you work with large files. Below that, updates can fail and the Mac slows down when it needs swap space.

Get warned before the disk fills up

Tempo for Mac shows free space on your startup disk in the menu bar and the Storage page, and can notify you when free space drops below the level you choose.