The “System Data” category in macOS storage management is frequently the largest consumer of disk space on modern Mac SSDs. This label encompasses everything from local Time Machine snapshots and APFS file system metadata to expansive application support libraries and cached assets.
When this partition scales beyond 100GB, it typically indicates a failure in the operating system’s automated maintenance routines or problems from third-party software. Managing this bloat requires moving past the basic Storage settings and targeting specific directories where macOS stores non-user-facing files that are obsolete.
How To Clean System Data on Mac?
1. Use Third-Party Software
You have several options when it comes to third-party software for decluttering your Mac, but I personally recommend Intego Washing Machine X9. By targeting unnecessary files that hog resources, this app doesn’t just free up storage—it significantly optimizes your system’s overall performance and responsiveness.
What sets this utility apart is its ability to identify and remove “digital junk” that standard manual cleanups often miss, such as broken aliases, localized language files you’ll never use, and redundant cache data. By automating these maintenance tasks, it ensures your operating system stays lean and responsive without the risk of accidentally deleting your important personal documents.
=> Get Intego Washing Machine X9
2. Clear Caches and Logs Manually
If you prefer a hands-on approach, the primary culprit for a bloated System Data bar is the user Library cache. These files are meant to speed up your apps, but they often fail to delete themselves after the app is closed.
- Open Finder and select Go > Go to Folder from the menu bar.
- Type
~/Library/Caches/and press Enter. - Review the folders and delete the contents of folders belonging to apps you no longer use.
- Repeat the process for the global cache at
/Library/Caches/.
3. Purge Time Machine Local Snapshots via Terminal
When your Mac is unable to connect to its external backup drive, it creates “local snapshots” on your internal SSD. While macOS is supposed to delete these when space is low, it often fails to do so on newer versions like macOS Sequoia.
- Open Terminal (found in Applications > Utilities).
- Type
tmutil listlocalsnapshots /and press Enter. - If you see a list of dates, type
tmutil deletelocalsnapshots [date]replacing[date]with the numerical string from the list. - Enter your admin password when prompted to finalize the purge.
4. Remove Hidden iOS and iPadOS Backups
If you have ever synced an iPhone to your Mac, a full copy of that device might be hiding in your System Data. These backups do not appear in your Documents folder but are stored deep within the MobileSync directory.
- Go to the Apple Menu > System Settings > General > Storage.
- Scroll down to the bottom and click on iOS Devices.
- Select any old backups you no longer need and click Delete.
- Alternatively, use the “Go to Folder” path
~/Library/ApplicationSupport/MobileSync/Backup/to find them manually.
Tips for Preventing System Data Bloat
To keep System Data from ballooning in the future, get into the habit of restarting your Mac at least once a week. This triggers native macOS maintenance scripts that clear out temporary swap files and “purgeable” data. Additionally, avoid keeping dozens of browser tabs open for weeks; modern browsers like Safari and Chrome create massive “Webkit” caches that are categorized as System Data and can grow to over 20GB if the app is never fully quit.
FAQ
Why is my System Data so huge on macOS Sequoia?
In macOS Sequoia, the system uses “firm links” and local snapshots more aggressively. If you haven’t performed a Time Machine backup recently, the system retains local snapshots indefinitely, which are categorized as System Data.
Can I delete everything in the ~/Library/Caches folder?
Yes, it is generally safe to delete the contents of this folder. Your apps may take slightly longer to load the first time you open them afterward, as they need to rebuild the necessary cache files.
How do I see what is actually inside System Data?
Since System Data isn’t a single folder, you must use a disk visualizer or the Terminal command du -sh * within the root directory to see which hidden system folders are consuming the most gigabytes.
Does “Optimize Storage” help reduce System Data?
The “Optimize Storage” feature primarily moves TV shows, movies, and email attachments to iCloud. While it helps overall storage, it has a minimal impact on the hidden logs and caches that make up the bulk of System Data.