How to Clear "System Data" Storage on Your Mac

System Data is not one thing you can delete. It is the catch-all in System Settings > General > Storage for everything macOS does not count as apps, documents, photos or another named category. To shrink it you clear its parts one at a time: caches, logs, local Time Machine snapshots, old device backups and developer files. macOS manages some of it by itself, so the figure never reaches zero and often changes after a restart.

1. Restart, then check the figure

1. Restart the Mac. Temporary files and swap space are cleared at startup.
2. Open System Settings > General > Storage and wait until the bar stops calculating. This can take a few minutes.
3. Note the System Data figure so you can tell what each later step changes.

2. Clear user caches and logs

1. Quit your open apps.
2. In Finder choose Go > Go to Folder, type ~/Library/Caches and press Return.
3. Sort by size, open the largest folders and move their contents to the Trash. Leave the folders themselves.
4. Do the same in ~/Library/Logs.
5. Empty the Trash.

Apps rebuild their caches, so expect some of this space to be used again over the following days. Do not clear other Library folders: Application Support and Containers hold real app data.

3. Check local Time Machine snapshots

If you use Time Machine, macOS keeps local snapshots on the startup disk. It removes them by itself as they age or when space is needed, but you can look. In Terminal, run:

tmutil listlocalsnapshots /

Each snapshot name contains a date stamp. To delete one, pass that stamp, for example:

sudo tmutil deletelocalsnapshots 2026-05-01-101500

Deleting a local snapshot does not touch the backups on your Time Machine drive.

4. Remove old iPhone and iPad backups

Device backups made on this Mac are stored in your Library and can be large, often several gigabytes each.

1. Connect the device and select it in the Finder sidebar.
2. On the General tab, click Manage Backups.
3. Select a backup you no longer need and click Delete Backup.

Keep the latest backup of any device you still use.

5. Clear developer files, if you have them

Skip this step if you do not write software. If you do, these are frequent causes of a very large System Data figure.

• Xcode build data: delete the contents of ~/Library/Developer/Xcode/DerivedData. Xcode rebuilds it the next time you build a project.
• Old simulators: run xcrun simctl delete unavailable in Terminal to remove simulator devices that the installed Xcode can no longer use.
• Docker: unused images and build cache live inside the Docker disk image. Review them in Docker Desktop, or run docker system prune after reading what it will remove.
• Package managers: Homebrew users can run brew cleanup to remove old downloads and outdated versions.

What MacPrune does about it

MacPrune v2.0 does not treat System Data as one item either. Its Disk page draws a map where every folder is a tile sized by the space it takes, so you can see which Library folders are behind the figure. The app asks for Full Disk Access so it can measure the whole disk. The map is for looking only.

The Clean page runs one scan and groups what it finds. Safe to clean covers user caches, browser caches, the Trash, system logs, Xcode data and package manager caches. Handle with care holds iOS backups and Docker data, kept apart so they are never removed without a deliberate choice. If you run local AI tools, the AI page shows the disk used by their models and caches, which macOS can also count as System Data.

Selected items move to the Trash after a confirmation, and the space is freed when the Trash is emptied. MacPrune does not list or delete Time Machine snapshots, so use step 3 for those. The basic version is free and cleans user caches, browser caches and the Trash. Pro, a one-time purchase, unlocks the rest: see pricing.

Where to go next

If System Data is still large, read Mac storage full with nothing to delete. Developers should see the Xcode storage fix, and the wider checklist is in how to free up Mac storage.