How to reinstall macOS
Use macOS Recovery, your computer’s built-in recovery system, to reinstall the Mac operating system.
Make a backup
Reinstalling macOS doesn’t remove your apps or personal data, but it’s still a good idea to back up your Mac first, if possible.
Start up from macOS Recovery
Follow the steps to start up from macOS Recovery. Then return to this article and continue to the next section.
Reinstall from macOS Recovery
From the list of utilities that you see in macOS Recovery, select the option to reinstall macOS. Then click Continue and follow the on-screen instructions.
If the installer asks to unlock your disk, enter the password that you use to log in to your Mac.
If the installer offers the choice between installing on ‘Macintosh HD’ or ‘Macintosh HD – Data’, choose Macintosh HD.
If the installer doesn't see your disk, your disk may have an issue that requires you to use Disk Utility to erase it. If Disk Utility can’t erase it, your Mac may need service.
Allow installation to complete without putting your Mac to sleep or closing its lid. Your Mac may restart and show a progress bar several times, and the screen may be empty for minutes at a time.
When installation is complete, your Mac might start up to a setup assistant. Follow the steps in the setup assistant.
If you're selling, trading in, or giving away your Mac, quit the setup assistant without completing setup, then click Shut Down. When the new owner starts up the Mac, they can use their own information to complete setup.
Which macOS version does Recovery install?
On a Mac with Apple silicon, Recovery installs the current version of the most recently installed macOS. If you installed a macOS upgrade and then used Disk Utility to erase the disk, you may get the macOS that you were using before upgrading.
On any other Mac, if you used Command-R to start up from Recovery, you get the current version of the most recently installed macOS. If you used Option-Command-R, you may get the latest macOS that is compatible with your Mac. If you used Shift-Option-Command-R, you may get the macOS that came with your Mac, or the closest version still available.
If you need help
If you can’t complete installation from macOS Recovery, make sure that your Mac is connected to the internet,* and find out what to do if an error occurred while installing macOS.
Find out what to do if your Mac doesn’t start up all the way.
If you still can’t install macOS from Recovery, find out about other ways to install macOS, and if necessary contact Apple Support.
* You need a broadband internet connection that uses DHCP over Wi-Fi or Ethernet. Some types of network connections can prevent installation from macOS Recovery, including those that use a required captive-network login, 802.1X security or PPPoE (unless a router is handling the PPPoE connection).
