How to free up space on a Mac: what is safe and what is not

When the disk is nearly full, work from the safest, largest wins down to the fiddly ones. Stop as soon as you have enough room.

Safe and quick

• Empty the Trash, and turn on Settings → General → Storage → Empty Trash Automatically.
• Open Downloads, sort by size, and delete old installers and disk images (.dmg, .pkg, .zip).
• Uninstall apps you no longer use. Dragging to the Trash leaves some data behind, but the app itself is usually the largest part.
• Restart the Mac so temporary files and purgeable caches are cleared.

Moderate effort, often large

• Review old iPhone/iPad backups.
• Delete Time Machine local snapshots if the disk is critically low.
• Clear Xcode Derived Data and unused simulators if you develop for Apple platforms.
• In the Photos app, delete duplicates and “Recently Deleted”. Don’t remove files from inside the Photos library package in Finder.

Use with care

• App caches in ~/Library/Caches: quit the app first, delete only that app’s folder, and expect it to rebuild.
• Anything in /System, /Library or application support folders you cannot identify. Leave it.

What not to do

Don’t run “one-click optimizer” scripts you don’t understand, and don’t delete the Mail, Messages or Photos databases to save space. Back up anything important with Time Machine first.

If you would rather see the sizes before touching anything, McCleaner scans your System Data for free and only changes files you explicitly pick.

Disclosure: this guide is published by the developer of McCleaner. Scanning is free; cleaning is paid, from €1.99. Back up important data before deleting anything. Commands are provided as is.