APFS System Data can occupy a large amount of storage on a Mac. To free it up, start by restarting your Mac, emptying Trash, removing local Time Machine snapshots, deleting old iPhone or iPad backups, and clearing safe-to-remove caches and installers. Do not delete random files from protected system folders: some items shown as “System Data” are required by macOS and cannot be safely removed manually.
Quick Answer
To reduce APFS System Data:
- Check storage in System Settings > General > Storage.
- Restart your Mac and install available macOS updates.
- Empty Trash and remove large files you no longer need.
- Delete old iPhone, iPad, and Mac backups.
- Remove local Time Machine snapshots if they are consuming space.
- Clear only user-level caches and old installers.
- Use Disk Utility or Terminal to investigate APFS volumes when the reported size seems incorrect.
The “System Data” category is broad. It can include caches, logs, virtual memory, local snapshots, app support files, backups, disk images, and data that macOS has not yet classified more specifically.
What APFS System Data Means
APFS is Apple’s file system for modern Mac startup disks. It organizes storage into an APFS container that can hold several related volumes, including the macOS system volume, a writable data volume, a recovery volume, and other hidden volumes.
In System Settings > General > Storage, macOS groups many types of files under System Data. This does not mean all of that space belongs to the macOS operating system itself. It is often a mixture of:
- Temporary files and application caches
- System and application logs
- Virtual memory and sleep-related files
- Local Time Machine snapshots
- iPhone and iPad backups
- macOS installers and update files
- App support data
- Mail attachments and message indexes
- Disk images and archive files
- Files that macOS has not assigned to another storage category
Some of this storage is reclaimable automatically. macOS may remove temporary files or local snapshots when more space is needed. Other items require manual cleanup.
Check How Much Space System Data Uses
Before deleting anything, record the current storage breakdown. This helps you determine whether the cleanup actually worked.
- Choose Apple menu > System Settings.
- Click General in the sidebar.
- Click Storage.
- Wait for the storage categories to finish calculating.
- Note the size shown for System Data and the amount of available space.
On older versions of macOS, choose Apple menu > About This Mac, click Storage, and then select Manage if that option is available.
Storage calculations can take time and may change after a restart. The categories are estimates rather than a complete inventory of every file on the disk.
Safe Ways to Free APFS System Data
1. Restart your Mac
A restart is a simple first step because it can remove temporary files and close processes that are holding space.
Before restarting, save your work. A restart closes open apps and can cause unsaved changes to be lost.
- Save documents and close open apps.
- Choose Apple menu > Restart.
- After the Mac starts, check System Settings > General > Storage again.
If the System Data figure drops after restarting, temporary files, swap data, or storage calculations were likely contributing to the total.
2. Install available macOS updates
A partially downloaded or outdated macOS update can occupy storage. Installing the available update may complete the process and remove temporary installation files.
Save your work and make sure the Mac is connected to power if it is a notebook.
- Open System Settings.
- Click General.
- Click Software Update.
- Install an available update by following the onscreen instructions.
Do not shut down the Mac while an update is installing unless macOS specifically instructs you to do so.
3. Empty Trash
Files moved to Trash continue using disk space until Trash is emptied.
Warning: Emptying Trash permanently deletes its contents. Restore anything you may need before continuing.
- Open Trash from the Dock.
- Review the files.
- If you are certain you no longer need them, click Empty.
- Confirm the action if prompted.
If a file cannot be deleted because it is in use, close the related app and try again.
4. Remove large files and old installers
Large disk images, compressed archives, duplicate downloads, and old application installers are easy to overlook. They may be counted as System Data or another broad category.
- Open System Settings > General > Storage.
- Review categories such as Documents, Downloads, Applications, and iOS Files.
- Select an item or category to see deletion options.
- Remove files you recognize and no longer need.
- Empty Trash afterward.
Be especially careful with files in Downloads. An installer may be the only copy of an app or utility you have saved.
You can also use Finder:
- Open Finder.
- Select Downloads or another likely folder in the sidebar.
- Choose View > as List.
- Click the Size column to sort by file size. If the column is not visible, Control-click a column heading and select Size.
- Move unnecessary files to Trash.
5. Delete old iPhone and iPad backups
Local device backups can be large and may appear under System Data or iOS-related storage.
Warning: Deleting a backup removes that local restore point. Keep at least one backup you may need, and do not delete your only backup without understanding the consequences.
- Connect the iPhone or iPad if necessary.
- Open Finder.
- Select the device in the sidebar.
- Click the General tab.
- Click Manage Backups.
- Review the listed backups.
- Select an obsolete backup and click Delete Backup.
If your Mac uses an older macOS version with iTunes, open iTunes and look for the device backup management options in its settings.
6. Remove old macOS installers
A full macOS installer can take several gigabytes. Look in the Applications folder for items named Install macOS [version].
Warning: Do not delete an installer if you plan to use it to upgrade or create an installer disk. Downloading it again may be necessary.
- Open Finder.
- Select Applications in the sidebar.
- Look for an Install macOS app.
- Move obsolete installers to Trash.
- Empty Trash.
Also check Downloads for update packages, disk images, and installer files you no longer need.
7. Reduce application cache and support data carefully
Caches are temporary files that help apps load faster. Removing some user caches is generally safe because apps can recreate them, but it may sign you out of apps, remove temporary data, or make the next launch slower.
Close the affected apps before removing their caches. Save your work first.
- Open Finder.
- Choose Go > Go to Folder.
- Enter:
~/Library/Caches
- Review the folders inside.
- Delete cache contents only for apps you recognize.
- Empty Trash if the files are no longer needed.
Do not delete the entire ~/Library folder. Avoid removing folders from /System/Library or /Library unless you know exactly what they contain. Many items in these locations are required by macOS or installed software.
App support folders may contain important libraries, plug-ins, databases, or user data. Do not remove them simply because they are large. Check the app’s own settings or documentation first.
8. Review Mail and Messages attachments
Mail and Messages can retain downloaded attachments and databases. Their storage may be classified as System Data.
Use the apps’ built-in controls where available. In Mail, search for messages with large attachments and delete messages you no longer need. In Messages, review conversations and attachments before deleting them.
Warning: Deleting a message or attachment can remove it from the Mac and, depending on your account and synchronization settings, from other devices as well. Confirm what will be removed before proceeding.
Remove Local Time Machine Snapshots
Time Machine can create local snapshots on an APFS startup disk when your backup disk is unavailable. These snapshots allow you to restore older versions of files, but they can occupy significant space. macOS normally treats this space as available when needed.
To inspect snapshots:
- Open Terminal from Applications > Utilities.
- Run:
tmutil listlocalsnapshots /
This lists local snapshots for the startup volume. A snapshot name may look similar to:
com.apple.TimeMachine.2024-01-01-120000.local
To delete one specific snapshot, use its date and time:
sudo tmutil deletelocalsnapshots 2024-01-01-120000
Enter your administrator password when prompted. The password will not appear as you type.
This command changes Time Machine’s local restore history by deleting the selected snapshot. Use the exact timestamp shown by the listing command. There is no ordinary undo command for a deleted snapshot, so keep a separate Time Machine backup if you need older versions of files.
You can also ask macOS to thin local snapshots by requesting a target amount of free space:
sudo tmutil thinlocalsnapshots / 20000000000 4
The number is measured in bytes; this example requests approximately 20 GB of reclaimed space. macOS may reclaim less if it cannot remove enough eligible snapshots.
After managing snapshots, restart the Mac and check storage again. For more advanced inspection of APFS structures, see How to Check APFS Containers and Volumes in Terminal on a Mac.
Check APFS Storage with Disk Utility
Disk Utility can show the physical disk, APFS container, and volumes. This is useful when Finder or Storage settings report a confusing amount of used space.
- Open Disk Utility from Applications > Utilities.
- Choose View > Show All Devices.
- Select the internal physical disk in the sidebar.
- Expand the APFS container.
- Review the listed volumes and their capacity information.
Do not erase, partition, delete, or restore a volume just to reduce System Data. Those actions can destroy files or make macOS unable to start.
APFS volumes in the same container can share free space. A volume may appear nearly full even when the container has available capacity, so do not judge the situation from one volume’s number alone.
Troubleshooting
System Data is still very large after cleanup
Restart the Mac, wait for storage to recalculate, and check again later. macOS may need time to index files and update the storage categories.
Then check these common sources:
- Local Time Machine snapshots
- iPhone and iPad backups
- Large files in Downloads
- Old macOS installers
- Mail or Messages attachments
- Virtual machines and developer tools
- Cloud-sync folders with local copies
- Large application support folders
Do not delete files merely because they appear in a large folder. Identify the app or service that created them first.
Storage does not add up
The Storage panel may classify files differently from Finder, and APFS shared space can make volume totals confusing. Hidden files, snapshots, purgeable data, and system-managed space may not appear in a simple folder-by-folder comparison.
Use Disk Utility to view the APFS container and volumes. You can also use Terminal to inspect disk usage, but do not use broad deletion commands to solve a reporting discrepancy.
A file will not delete
Close the app using the file and try again. If the item is part of a backup, snapshot, or protected system location, macOS may prevent manual deletion. Do not bypass those protections unless you understand the file’s purpose and have a current backup.
The Mac is nearly full
Free a small amount of space first by removing known large files from Downloads, deleting an obsolete installer, or emptying Trash. Then restart and continue the investigation.
Avoid running large updates or creating new backups while the startup disk has almost no free space. If necessary, copy personal files to a separate, verified external drive before deleting them from the Mac.
Frequently Asked Questions
Is it safe to delete APFS System Data?
Not as a single category. System Data includes both removable files and data required by macOS. Remove identifiable caches, old backups, installers, and snapshots instead of deleting unknown system files.
Why does System Data keep growing?
It may grow because of caches, logs, local snapshots, backups, virtual memory, app data, or cloud and messaging attachments. Some growth is temporary and macOS may reclaim it automatically.
Can I delete the APFS container?
No. Erasing an APFS container deletes its volumes and can remove macOS, apps, and personal files. Use Disk Utility only for diagnosis unless you intentionally plan to erase and reinstall with a complete backup.
Will deleting local Time Machine snapshots delete files?
Deleting a local snapshot removes that snapshot’s restore point. It does not normally delete the current files on your Mac, but it does reduce the available local history.
Should I use a cleaning app?
A cleaning app is not required for the steps in this guide. If you use one, review every proposed deletion and avoid tools that remove protected system files, backups, or application data without clearly identifying them.
Final Thoughts
APFS System Data is a broad storage category, not one folder you can safely delete. Start with reversible, identifiable cleanup: restart your Mac, remove old backups and installers, empty Trash, review caches carefully, and manage local Time Machine snapshots when appropriate. Keep a current backup before deleting important data, and use Disk Utility for investigation rather than destructive changes.