How to reduce System Data on a Mac: 8 safe fixes

Every fix uses tools built into macOS and works on any MacBook Air, MacBook Pro, iMac, Mac mini or Mac Studio. The menus match macOS Ventura and later.

The short answer

Try these five steps first. They solve most cases:

1. Restart your Mac.
2. Delete local Time Machine snapshots.
3. Clear app and browser caches.
4. Remove files that uninstalled apps left behind.
5. Clean up Xcode, Docker and other developer files.

What is System Data on a Mac?

So what is System Data on a Mac? It is the storage category for files that don’t fit anywhere else, such as Applications, Documents or Photos. It mostly holds temporary and support files that apps and macOS create as they run. Before macOS Monterey, Apple called it Other storage, so any advice on how to clear Other storage on a Mac applies here too.

System Data is not the same as the macOS category. That one holds the operating system itself, which macOS seals and protects, so you can’t shrink it.

What System Data includes

Why is System Data so large on a Mac?

If you’re wondering why System Data is so large on a Mac, a few common causes explain most cases:

• Time Machine snapshots pile up when your backup disk stays unplugged, because macOS keeps hourly snapshots on your Mac until it can back them up.
• Caches never stop growing. Browsers, Slack, Spotify and creative apps can each hold several gigabytes.
• Developer tools are heavy. Xcode build data, simulators and Docker images often reach tens of gigabytes.
• Deleted apps leave files behind. Dragging an app to the Trash keeps its support files.
• Storage settings lags behind. macOS can take several minutes to recalculate after you delete something.

Check how much System Data your Mac has

Choose Apple menu, then System Settings, then General, then Storage. Wait for the bar to finish loading, then hold the pointer over its grey section to see the System Data total. Write it down so you can measure your progress.

Find the biggest folders yourself

In Finder, choose Go, then Go to Folder, and enter ~/Library. Switch to list view, choose View, then Show View Options, and tick Calculate all sizes. Click the Size column to put the largest folders first.

Prefer Terminal? Run du -sh ~/Library/* | sort -h | tail -10 to list the 10 largest folders in your Library.

How to clear System Data on a Mac: 8 safe fixes

To clear System Data on a Mac safely, work through the fixes in order. The first ones carry the least risk and often free the most space.

1. Restart your Mac

A restart clears swap files, temporary files and stale caches that macOS creates while it runs. It also lets macOS release purgeable space. If you haven’t restarted in weeks, this step alone can free several gigabytes.

2. Delete local Time Machine snapshots

Snapshots are often the single largest part of System Data. The easiest fix is to connect your backup disk and let Time Machine finish a backup. To remove snapshots right away, open Terminal and run tmutil listlocalsnapshots /. Then delete each one with sudo tmutil deletelocalsnapshots 2026-10-28-120000, using a date from the list.

3. Clear app and browser caches

Open ~/Library/Caches with Go to Folder. Quit an app, then delete the contents of its folder. Leave the Caches folder itself in place. Apps rebuild what they need on their next launch.

Safari

Choose Safari, then Settings, then Advanced, and turn on Show features for web developers. Then choose Develop, then Empty Caches.

Chrome

Open Settings, then Privacy and security, then Delete browsing data. Select only Cached images and files so you stay signed in.

4. Delete old log files

Open ~/Library/Logs and delete old logs and the crash reports in DiagnosticReports. They rarely take much space, but a misbehaving app can write gigabytes of logs in a few days.

5. Remove leftovers from uninstalled apps

Check ~/Library/Application Support and ~/Library/Containers for folders named after apps you no longer have. Delete only those that clearly belong to removed apps. When in doubt, leave the folder.

6. Clean up developer files

If you write code, this fix often frees more space than all the others combined.

Xcode

Delete ~/Library/Developer/Xcode/DerivedData and old folders in ~/Library/Developer/Xcode/iOS DeviceSupport. Run xcrun simctl delete unavailable to remove simulators for iOS versions you no longer use.

Docker

Run docker system prune to remove stopped containers and unused images. Docker lists what it will delete and asks you to confirm first.

Homebrew and npm

Run brew cleanup to remove old package versions, and npm cache clean --force to clear the npm download cache.

7. Rebuild the Spotlight index

A damaged Spotlight index can grow far beyond its normal size. Open System Settings, then Spotlight, and click Search Privacy. Add your startup disk, wait a minute, then remove it. Spotlight rebuilds a fresh, smaller index, and search works more slowly until it finishes.

8. Update macOS

Some macOS releases contain bugs that let System Data grow out of control, and Apple fixes them in later updates. Choose System Settings, then General, then Software Update, and install any update it offers.

How to reduce System Data on a MacBook with little storage

On a MacBook Air or MacBook Pro with 256 GB, System Data hurts more because there is less room to spare. These habits help you reduce System Data on a MacBook and keep it low:

• Keep at least 20 GB free. macOS needs room for swap files, updates and snapshots, and it clears snapshots more aggressively when space runs low.
• Connect your backup disk often. Each completed backup lets macOS clear older local snapshots.
• Restart once a week. Regular restarts stop swap and temporary files from building up.
• Turn on Store in iCloud. Moving documents and photos to iCloud frees room for the files macOS needs.

For more ways to make room beyond System Data, read our guide on how to free up space on a Mac.

What not to delete

When you clear System Data on a Mac, some files look like clutter but keep it running. Leave these alone:

• The System folder and the top-level Library folder. macOS needs them to start up.
• Swap files in /private/var/vm. macOS creates and removes them as needed.
• Anything in /private/var/folders. macOS clears these temporary files itself, and deleting them by hand can crash running apps.
• Folders for apps you still use. They hold your settings, data and sign-ins.

See what’s inside System Data with MyMacStorage

Storage settings shows System Data as one grey block. MyMacStorage opens it up. One scan names each part, from caches and snapshots to developer files and app leftovers, and shows its size so you know what is safe to clear.

Nothing is deleted outright. Every cleanup goes to the Trash, and Undo puts it back. Learn more about MyMacStorage, the disk cleanup app for Mac. It costs $19.99 once, with no subscription.

Frequently asked questions