Updated Oct 2026

What is System Data on Mac, and how to clear it safely

What is System Data on Mac?

Apple’s definition: System Data “contains files that don’t fall into the categories listed here. This category primarily includes files and data used by the system, such as log files, caches, VM files, and other runtime system resources. Also included are temporary files, fonts, app support files, and plug-ins. You can’t manage the contents of this category” (Apple Support).

Before macOS 12, most of this showed up as Other (Macworld). It’s the same idea under a new name.

What’s usually inside

What	Where it lives	Safe to remove?
Local Time Machine snapshots	APFS snapshots on your startup disk	Usually yes, if you have a real Time Machine backup. macOS should purge them when space runs low (Apple) and this can fail (Eclectic Light).
iPhone and iPad backups	`~/Library/Application Support/MobileSync/Backup`	Yes for old devices, after checking you have an iCloud backup or don’t need it
App caches	`~/Library/Caches`	You can delete a cache folder while that app is closed. It grows back, and the app is slower until it rebuilds.
Logs	~/Library/Logs and /Library/Logs	Small, rarely worth it
Virtual machine and container images (Parallels, UTM, Docker)	App-specific, often ~/Library/Containers or ~/Library/Group Containers	Only from inside the app that made them
App support data (Xcode, Adobe, games, chat apps)	`~/Library/Application Support`	Only from the app, or after uninstalling it
iCloud Drive local copies	`~/Library/Mobile Documents` (Apple Community)	Use Optimize Mac Storage or Remove Download in Finder
macOS swap and sleep image	`/private/var/vm`	No. macOS manages these. Restarting frees swap.

Why is System Data so large?

Big System Data is normally one or two large things: snapshots after a big file move, an old iPhone backup, a VM image, or a developer tool’s caches. Reports of System Data passing 100 GB are common, and people have reported jumps after macOS updates (macworld.info). The number also changes from hour to hour, because Apple says the category “varies in size depending on the current state of your Mac.”

How to clear System Data on Mac safely

Back up with Time Machine to an external drive before you start. Work through these in order, checking Storage after each.

1. Restart your Mac

Restarting clears swap and some temporary files. It costs nothing, so do it first and let Storage recalculate.

2. Delete old iPhone and iPad backups

System Settings > General > Storage.
Click the info button next to iOS Files (if shown).
Select backups for devices you no longer own and click Delete.

3. Remove local Time Machine snapshots

List them in Terminal:

tmutil listlocalsnapshots /

Delete one by its date:

sudo tmutil deletelocalsnapshots 2026-10-01-101500

Or ask macOS to thin them to free space:

sudo tmutil thinlocalsnapshots / 999999999999 4

Commands from Apple’s tmutil man page (tmutil(8)). Snapshots are created again on the next backup. Deleting them doesn’t touch your external Time Machine backup.

4. Clear big app data from inside the app

VMs: delete unused virtual machines in Parallels, UTM, or VMware.
Docker: remove unused images and volumes in Docker Desktop, or run docker system prune after reading what it removes.
Xcode: delete old simulators and ~/Library/Developer/Xcode/DerivedData.

5. Clear caches (with low expectations)

Open ~/Library/Caches from Finder > Go > Go to Folder. You can delete the contents of a large app’s cache folder while that app is closed. Don’t delete the Caches folder itself, and leave anything under /System alone. Caches rebuild, so expect the space to fill again within days.

6. Check for space that’s yours in the wrong bucket

Some data you think of as yours can show up in odd places, like downloaded iCloud Drive files. Messages attachments get their own Messages category in Storage. If that one is large too, see Messages taking up space on your Mac.

What not to delete

Anything under /System, /private/var/db, or /private/var/vm.
The ~/Library folder or whole subfolders like Application Support or Containers.
Files you don’t recognize. Search the folder name first.

Where Super Duper Space helps

Apple’s Storage pane shows one System Data number and says you can’t manage that category. Super Duper Space measures accessible files on your Mac and groups them by app. Open a group to read what it is, why it grows, and what removing it would do. Those sizes are the app’s own measurement. They differ from the System Data number in System Settings, and the scan does not copy that number out of System Settings.

Most of that list is an explanation. The app does not delete files under /System, and it has no root helper. Cleanup outside Messages refuses protected folders such as Application Support, Containers, Mail, and iCloud Drive. It does not remove Time Machine snapshots. What it will delete, after you confirm, is Messages attachments, plus some developer leftovers (Xcode build data, npm, pnpm, and Homebrew caches, and leftover app-updater folders), unzipped downloads, and personal-file copies you pick. Caches and snapshots can come back on their own. It’s in private beta.

Join the private beta

FAQ

Can I delete System Data on Mac?

Apple does not offer one delete for the whole category. Apple says you can’t manage the contents of this category directly. You can shrink it by removing what’s inside: old iPhone backups, local snapshots, VM images, and large caches.

Is it safe to delete System Data?

Some of it. Old iPhone backups, local Time Machine snapshots (with a real backup), and app caches are safe to remove. System files, swap, and app databases are not. Back up first.

Why does System Data keep growing?

Caches and snapshots come back with normal use, and apps keep adding support files. Growth after a macOS update is common and often settles after a few restarts.

How do I clear System Data with Terminal?

tmutil listlocalsnapshots / lists snapshots, and sudo tmutil deletelocalsnapshots <date> removes one. Avoid scripts that delete whole Library folders.

What was Other storage on Mac?

The old name. macOS 12 and later call it System Data (Macworld).

Do Mac cleaner apps clear System Data?

They clear caches, logs, and leftovers, which are part of System Data. They can’t remove what macOS protects, and caches come back.

Is 100 GB of System Data normal?

It isn’t unusual, and it usually means one large item such as snapshots, an iPhone backup, or a VM. Check those first.