How to clean reinstall macOS from Recovery Mode?

By Amanda | Posted to Home > Howto, Updated on January 18th, 2022

Summary: This article tells all ways to reinstall Mac OS X or macOS using Mac Recovery mode, including clean reinstall different versions of macOS without losing data.

How to reinstall macOS from Mac Recovery

If you want to have a fresh copy of macOS on your Mac or free up space on Macintosh HD, this article will tell you how to securely delete your personal files and install a clean version of macOS in Mac Recovery Mode.

What happens when you reinstall macOS in Mac Recovery Mode

Mac Recovery Mode is a special startup mode that can load up many useful troubleshooting and recovery tools without booting up regular OS. It is the easiest way to reinstall macOS from scratch.

Reinstalling macOS cleans the codes of current operating system and rewrites every line of code for the operating system on your Mac. As a result, it can fix bugs and errors causing an underperformed Mac or a Mac experiencing a macOS kernel panic.

Reinstalling macOS in Recovery partition usually won't change the version you are running on your Mac, but later we will show you how to install the original system installed on your Mac when it left the factory, or the latest compatible system.

An OS reinstallation shouldn't delete any user data as long as your operating system and user files write in separate volumes. If not, reinstalling macOS will wipe all your documents, photos, videos, audio, and everything else you created or downloaded.

Before you start, make sure you have backed up any files you want to keep to an external drive. Even though you don't intent to wipe your MacBook, securing your files is a good idea before OS reinstallation since it is a major procedure.

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How to reinstall the current version of macOS

1. Start Mac in Mac Recovery Mode

On an Intel Mac, just shut down your Mac completely and turn it on while holding down Command + R keys simultaneously. Release the keys until you see an Apple logo and your Mac will boot into the macOS Utilities or OS X Utilities screen in recovery partition.

On an M1 Mac, shut down your Mac completely, press the Touch ID button to turn it on and then immediately press down the Touch ID button until you see "Loading startup options". Click Options and then click Continue to boot in macOS Recovery.

During the bootup to Recovery Mode, an admin password might be required to authenticate your identity for an OS reinstallation.

If you can't boot your Mac into recovery partition built in Mac's hard disk, you can use Internet Recovery Mode on an Intel Mac, or Fallback Recovery Mode on an M1 Mac to access the macOS utilities.

After you have the access to the recovery tools, you can proceed to format your startup drive and reinstall macOS from Mac Recovery Mode.

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2. Format Mac's startup disk (Optional)

If you want to reinstall a clean copy of operating system, but leave your user account and files you created intact and stay where they are, you can skip this step.

However, if you want a truly clean OS reinstallation and a smooth process without interruptions by potential startup disk corruptions or space shortage, formatting the Mac startup disk is necessary. It worth mentioning here again - make sure you have transferred your important files to a computer or external storage device.

Follow the steps below to get started:

Step 1: Click Disk Utility option and click Continue.

Step 2: Select the Macintosh HD or system volume with another name which contains the operating system and click Erase.

Step 3: Give a name to the volume you are going to format and then reinstall macOS in. It is highly recommended to use "Macintosh HD" for convenience's sake.

Macintosh HD Volume

Step 4: Select Mac OS Extended (Journaled) as Format for reinstalling macOS 10.12 or earlier, while select APFS for reinstalling macOS Monterey, macOS Big Sur, macOS Catalina, macOS Mojave, or macOS High Sierra.

Step 5: Click Erase Volume Group. This will delete Macintosh HD - Data volume the system created when you upgraded to macOS 10.15 or later and all other volumes you created as a user. Deleting all the volumes can free up space and eliminate possible conflicts for a clean macOS reinstallation. It is very essential when you need to reinstall macOS Big Sur on an M1 Mac.

Erase startup disk for macOS reinstallation

Step 6: Confirm the wiping by clicking the Erase button.

It will take a few minutes to half an hour to complete the disk formatting. Wait patiently and do not terminate it half way.

3. Reinstall macOS

After you have started up to macOS Utilities screen, you will see a round thumbnail next to Reinstall macOS option. It indicates what version of macOS will be installed on your Mac.

The thumbnail uses the typical wallpaper of a macOS version. For example, if you are going to reinstall macOS Catalina, it is an island in the sea. If you will reinstall macOS Mojave, it is dessert. Find all macOS versions and know what operating system will be downloaded and installed on your machine.

Then click Reinstall macOS option and Click Continue.

Reinstall macOS

You will be asked to select a destination to install the new copy of macOS and select the Macintosh HD you formatted earlier. The reinstallation will begin

reinstall macOs Catalina

Click Continue and then you will see a window with a progress bar and time remaining for installing OS. It will take a while and do not let your computer shut down or sleep. After the macOS reinstallation completes, your Mac will restart automatically and then ask you to create an admin account.

If you are selling, donating, trading, or giving away this Mac computer, you can simply shut down the Mac. If you will keep it, you can go ahead to create a new account and enjoy your fresh Mac.

How to reinstall different versions of macOS

If you start up an intel Mac using Command + R keys or start an M1 Mac in regular Mac Recovery, you will install the current version of macOS on your Mac. If you want to install the original version of macOS or the latest compatible version of macOS on your Mac, it will need extra operations.

How to reinstall the original version of macOS on your Mac?

You can only reinstall the original macOS your Mac shipped with on Intel Macs. To do so, you need to press down Command + Option + Shift + R keys while turning on a Mac. This will boot to Internet Recovery and download the original version of macOS from Apple servers according to your Mac model.

However, if the OS version is obsolete and no longer available, the closest and available version will be reinstalled instead.

How to reinstall the latest compatible of macOS on your Mac?

Before you boot into macOS Recovery for system reinstallation, you should go to Apple logo > System Preferences > Software Update to update your Mac to the latest version of macOS.

Or on an Intel Mac only, you can start up your machine with Command + Option + R keys pressed until a spinning globe appears. In this startup mode, after you click the Reinstall macOS feature, it will reinstall the latest version of macOS that is compatible with your Mac.