System Data, previously called Other on older macOS versions, is a catch-all storage category for files that do not fit cleanly into apps, photos, documents, or media. It can include useful temporary files as well as removable clutter.
This guide applies to the Storage panel in recent macOS versions.
Does This Affect You?
Use this if Storage settings show a large System Data or Other section and you are unsure whether it is normal or safe to reduce.
What System Data Contains
- Caches from apps, browsers, fonts, thumbnails, and macOS.
- Logs and diagnostic records, which macOS usually prunes over time.
- Time Machine local snapshots kept on the internal disk until a backup catches up or space is needed.
- iPhone and iPad backups, software updates, and support files.
- App containers and support files stored in your Library folder.
Do not randomly delete Library folders by hand. macOS and apps use many of these files, and manual cleanup can break logins, settings, or licensing.
Shrink It Safely
- Restart the Mac to clear temporary files and stale caches.
- Free obvious space elsewhere first, such as Downloads, old videos, unused apps, and Trash.
- Remove old iOS or iPadOS backups from Storage settings if they appear.
- Clear browser caches from within Safari, Chrome, or Firefox rather than Finder.
- Give macOS 24 to 48 hours to reindex and prune automatically.
When It Is Too Large
Normal Size
System Data around 15 to 40 GB can be normal on a Mac used for months. It becomes suspicious when it consumes a huge share of the disk.
Time Machine Backlog
Reconnect your Time Machine backup drive if it has been disconnected for a long time. Local snapshots may clear once backups complete.
Avoid Manual Library Cleaning
Deleting random folders in ~/Library/Caches or Application Support often saves less space than expected and can break apps.
Diagnostics
If System Data remains enormous after restarts, backups, and time, run Apple Diagnostics or contact Apple Support to check for runaway logs or disk issues.
Sources
- Apple Support: Storage settings on your Mac
- Apple Support: Free up storage space on your Mac
- Apple Support: Manage storage for apps and files on Mac