What happened to Other storage on a Mac?

Other is now System Data

Until macOS Big Sur, the coloured storage bar had a grey Other segment for everything it could not file under Apps, Documents, Photos or Mail. From macOS Monterey on, System Settings → General → Storage calls the same bucket System Data. A few kinds of file have headings of their own, such as iOS Files and Developer, and everything left over lands in System Data. So a guide that tells you to click Other is describing a Mac from before 2021.

What was in Other, and where it sits now

• Caches in ~/Library/Caches and the hidden ~/.cache: in System Data.
• Logs in ~/Library/Logs and /private/var/log: in System Data.
• App data in Application Support and Containers: mostly System Data, partly Applications.
• Local Time Machine snapshots: System Data, shown as purgeable.
• Disk images and archives (.dmg, .zip) left in Downloads: now under Documents.
• iPhone and iPad backups: under the iOS Files heading.
• Xcode and simulator data: partly under Developer, the rest in System Data.

Cleaning it, in order

1. Downloads. Sort by size and remove the installers and archives you have already used. This is the quickest win, and it is your own call what goes.
2. iOS backups. In Storage settings, open iOS Files and delete backups of devices you no longer have.
3. Caches. Quit your apps and empty ~/Library/Caches. They regenerate; the full steps are on how to clear the cache.
4. Developer files, if you write code: Xcode DerivedData and old simulator runtimes are often the largest single items on the disk.
5. Leftovers from deleted apps in Application Support and Containers. Check each folder before removing it; uninstalling apps properly explains how to tell whose is whose.
6. Restart. It clears macOS's temporary folder and lets it release swap and purgeable snapshots.

Measuring it yourself

Storage settings will not break the bucket down. A terminal will:

du -sh ~/Library/Caches ~/.cache ~/Library/Application\ Support ~/Library/Containers ~/Downloads 2>/dev/null
tmutil listlocalsnapshots /

The first line sizes the usual suspects; the second counts local snapshots, which macOS removes on its own when space runs short.

What not to touch

Leave /System, /private/var/vm (swap) and /private/var/folders alone while the Mac is running; macOS manages them, and a restart is the safe way to shrink them. And do not delete Application Support wholesale: some apps keep your only copy of your work there.

Where the app comes in

RefreshYourMac measures the places that used to make up Other as separate categories — caches, logs, Downloads, iOS backups, developer files, app containers — and rates each one with a safety level, so you can see which parts regenerate and which are yours before anything is removed. Application Support is shown and sized but marked Protected, because no tool can tell a cache from somebody's only copy of their work.