How to free up space on a Mac, safely

The safest space to reclaim on a Mac is anything the system or an app can rebuild: caches, build folders, package downloads and installers for apps you already have. Check what's large first, move things to the Trash rather than deleting them outright, and leave anything you didn't create alone.

Updated November 11, 2026 · Works on macOS 14 Sonoma and later

1. See where the space went

Open System Settings → General → Storage for a rough breakdown. For a folder-by-folder view you need a disk map. Foldy's Space Map draws every folder as a block sized by how much it holds, so a 40 GB folder three levels down is obvious.

2. Empty the Trash and old downloads

Files in the Trash still use space. In Downloads, sort by size: .dmg and .pkg installers for apps you've already installed can go.

3. Clear developer leftovers

If you write code, this is usually where the biggest wins are. All of these come back on their own:

• Xcode DerivedData in ~/Library/Developer/Xcode/DerivedData. Xcode rebuilds it on the next build.
• Old simulators: xcrun simctl delete unavailable removes ones for Xcode versions you no longer have.
• node_modules in projects you haven't touched for a while. npm install brings them back.
• Docker: docker system prune removes stopped containers, unused networks and dangling images.
• Homebrew: brew cleanup removes old versions and downloads.

4. Check app caches

Apps keep caches in ~/Library/Caches. They're rebuilt as needed, so clearing them is safe, though an app may be slower the first time you open it afterwards. Quit an app before clearing its cache.

5. Look at iPhone and iPad backups

Local device backups live in ~/Library/Application Support/MobileSync/Backup and can be tens of gigabytes. Delete old ones from Finder: select the device in the sidebar, then Manage Backups. Only remove backups you're sure you don't need.

What is “System Data”?

System Data is everything macOS doesn't sort into another category: caches, logs, local Time Machine snapshots, virtual memory and app support files. It shrinks when you clear caches and when macOS removes snapshots as space runs low. You can't delete it as a whole, and you shouldn't try.

What not to delete

• Anything in /System or /Library you don't recognise
• Photos and Music libraries, unless you've moved them elsewhere
• App support folders for apps you still use: they hold your settings and data

Doing it in one place

Foldy's Reclaim view finds all of the rebuildable items above, explains each one in plain words, and shows how much space it would free. Everything goes to the Trash first and every clean-up can be undone from History. Your photos, documents and projects are never suggested.