Why does my Mac say I have "Other" storage?

What macOS counts as "Other"

Pretty much anything that is not a recognized category. The categories Apple shows are:

• Apps
• Photos
• Mail
• Music
• TV
• Books
• Messages
• iCloud Drive
• Documents
• System Data (formerly called "System")
• macOS itself

Everything else - the things actually consuming your disk - falls into Other. That includes:

• Caches in ~/Library/Caches from every app you have ever used.
• Old iOS device backups in ~/Library/Application Support/MobileSync/Backup.
• Virtual machine disks (Parallels, VMware, UTM).
• Xcode's DerivedData, simulators, and archives. Easily 30-100 GB on a developer's machine.
• Container files from Docker.
• Email attachments downloaded by Mail.
• Browser caches and downloads not in ~/Downloads.
• Time Machine local snapshots, which look like free space to you but count as Other to the storage view.

What it is almost never

People assume "Other" means "essential macOS internals I must not touch". Almost never true. macOS itself is its own small category. The "Other" bar is mostly user-controlled stuff, you just cannot see it from the About This Mac view.

Time Machine snapshots are a special case worth knowing about: when you delete a file, macOS keeps a local Time Machine snapshot of it for up to 24 hours so you can restore. These snapshots count against Other but get automatically cleaned up. You normally do not need to do anything about them.

How to see what is actually there

The About This Mac view is intentionally vague. To see the truth, you need a tool that scans your disk file by file. Options:

• Finder's built-in size column: switch any folder to List view, show the Size column, and dig manually. Tedious but free.
• OmniDiskSweeper: a venerable free tool that gives you a column view of folders sorted by size.
• GrandPerspective or Disk Inventory X: free, classic treemap-style views.
• DaisyDisk: a paid app with a sunburst-style map.
• DiskSpace (ours): a sunburst map with safe-delete protections - cannot remove system-critical files even if you try.

Where the space usually is

Across many user machines we have looked at, the biggest single contributors to Other are, in rough order:

1. Old iOS device backups. A single iPhone backup can be 40-80 GB. If you have ever plugged in an iPhone and let it back up, the backup is still there.
2. Downloads folder. Installers, archives, and screen recordings nobody ever cleans up.
3. Xcode (if you are a developer). DerivedData, simulators, and old device support files.
4. Virtual machines. A single VM disk can be 30-150 GB.
5. Docker images. If you use Docker Desktop, the Docker.raw file can balloon to 60+ GB.
6. App caches. Big ones to watch: Photoshop, Spotify, Slack, Discord.

If you scan your disk and these add up to most of your "Other" number, you are normal. If they do not, keep digging - there is one specific giant file in there somewhere.