Verify Your Free Disk Space
You'll need 37 GB of free space to upgrade to macOS 13 or 14 (Ventura or Sanoma) or 26 GB of free space to upgrade to macOS 12 (Monterey) (or 44GB if you're upgrading from macOS 10.12 Sierra or older).
- From the Apple Menu, select About this Mac (macOS 11-12) or System Settings > General (macOS 13-14)
- Click on Storage
- You'll see how much used and free space your computer has
- If you are upgrading a dual boot machine, make sure there are 37 GB free under Macintosh HD - Windows is not relevant
- If you are short on disk space:
- Check your Desktop and Downloads folder for items you no longer need
- Take a look in your Applications folder and remove any applications you no longer need (some applications will have an Uninstaller app in their folder but most can just be moved to the trash)
- Empty your computer’s Trash
Check Your System Disk
- Go to your Applications folder (if you don't have this folder visible in your Dock, you can find it by clicking on your desktop and then clicking on the Go menu at the very top of your screen)
- Select Utilities > Disk Utility
- Click on Macintosh HD in the left-hand column
- Click on First Aid (older macOS versions may call this option Verify and may look like this)
- If you also have a Macintosh HD - Data disk listed, run First Aid (or Verify) for that HD as well
Disable FileVault or 3rd Party Disk Encryption
If you are using a third party Disk Encryption app for critical files (TrueCrypt, PGPDisk), please disable this before upgrading. Early versions of FileVault should also be turned off. See the Turn Off FileVault instructions.
Note: This can take a LONG time. You can typically continue to use your computer in the meantime, but estimates from 4 hours to over a day are not uncommon, and you may see a range of estimates throughout the process.
If you're doing this in preparation for a macOS upgrade....
Continue on to the next two steps in the process:
- Check the compatibility of your various applications
- Check the readiness of your disk