Not enough space to update macOS? What to clear first

Check how much the update needs, and how much you have

The message from Software Update or the installer says how much space it needs; Apple gives no fixed figure, because it changes with each update and each Mac. To see what you have, choose Apple menu → System Settings, click General, then Storage. The bar at the top shows what is used, by category, and updates as you free space.

What to clear first, in order

1. Empty the Trash. Apple's own warning: a file in the Trash still takes its space until the Trash is emptied. Check it first, because this is often where the gigabytes already are.
2. Old downloads and installers. Disk images (.dmg), installer packages (.pkg) and zip files in Downloads are rarely needed once the app is installed. See how to find your downloads.
3. Old iPhone and iPad backups. A single backup can be tens of gigabytes. Delete the ones for devices you no longer have, or that are backed up to iCloud: see old iPhone backups.
4. Apps you no longer use. Remove them with what they left behind: how to uninstall apps completely.
5. Large media. Move a Photos or iMovie library, or big video files, to an external drive. How to find large files shows where they are.
6. Caches. Apps rebuild them, so they are safe to clear and give space back at once, though it comes back over the following weeks: how to clear the cache.
7. A deleted user's folder. Apple suggests checking the Users folder on Macintosh HD for data left by accounts that were deleted. Look inside before you remove it: it may be someone's only copy.

Still a little short: start up in safe mode

Apple says safe mode "might provide enough storage space" for a task like installing a macOS update, because the Mac clears certain system caches when it starts that way. The space is only free while you are in safe mode, so install the update from there.

• Apple silicon: shut down, then press and hold the power button until you see Loading startup options. Select your startup disk, hold Shift and click Continue in Safe Mode.
• Intel: turn on or restart the Mac and hold Shift straight away, until the login window appears.

Log in, run Software Update, and when it is done choose Apple menu → Restart to leave safe mode. If the installer still fails with a message about something other than space, Apple's advice is to install macOS from macOS Recovery, where no other software can get in the way.

What not to delete in a hurry

• Folders in ~/Library other than Caches and Logs. Most of it is your apps' data: see what is safe to delete in the Library folder.
• System Data you can't identify. Much of it is purgeable, and macOS frees that by itself when space runs short: see what System Data is and purgeable space.
• The update that has already downloaded. It sits in a protected folder, and macOS would only download it again. Installing it is what frees that space.

Where the app comes in

RefreshYourMac measures the things above in one scan, each with its safety level, and the level decides what each button may do, so a hurried clean can't sweep up your own files. Two categories exist for exactly this moment, both in the download edition: Downloaded macOS Updates lists each update waiting in /Library/Updates by name, and tells you to install it rather than delete it; and Deleted User Account shows the size of a deleted user's leftover folder, without ever deleting it. To keep a Mac from getting this full again, the app can clean the safe categories automatically when free space falls below a level you choose. For the wider picture, see Mac storage full?