Oct 07, 2019 Partitioning your Mac is basically splitting your hard drive into separate, usable systems. It makes it possible to run two separate operating systems on one device, like Windows and macOS, or two versions of macOS (like Catalina and Big Sur). Sep 06, 2019 There are several reasons you might need to install a new copy of macOS or OS X on the hard drive in your Mac or MacBook. Fortunately, there are also several ways to do it, ranging from Internet recovery to installation discs.

If you've always wanted to partition your Mac's hard drive so you can run a separate operating system — including the launch of macOS Big Sur — in tandem with your current one, it's surprisingly easy to do so thanks to Apple's built-in disk utility program. Here's how to partition your Mac.

What is a disk partition?

Partitioning your Mac is basically splitting your hard drive into separate, usable systems. It makes it possible to run two separate operating systems on one device, like Windows and macOS, or two versions of macOS (like Catalina and Big Sur).

Note: If you want to run Windows on your Mac, Apple's Boot Camp assistant will automatically make a partition for you. Here's how to install Windows.

It is important to note that partitioning your hard drive also splits up your available hard drive space. Each partition will take up a portion of your usable storage. So, if you are running low on storage capacity on your hard drive, we don't recommend partitioning.

Before you start

The most important thing to do before making any changes to your hard drive is to back it up. Seriously. Back it up. Please. Time Machine is the easiest way to back up your data if you don't already have another system in place.

Second, make sure you have enough free disk space to properly run a secondary operating system. Shoot for at least 30GB free, though I recommend closer to 50GB if you have it available.

How to create a partition on your Mac

1. Open Finder from your dock.

2. Select Applications.

3. Scroll down and open the Utilities folder.

4. Double-click to open Disk Utility.

5. Select your hard drive in the Disk Utility window. It will be the first drive on the list. It might be named 'Fusion,' or 'Macintosh HD.'
6. Click on the Partition tab. You will be prompted to either add an APFS volume or a Partition.

7. Click Partition.

8. Click the Add partition button it looks like a plus (+) symbol.
9. Change the size of the partition you wish to use by dragging the resize controls. The used space is represented in blue.
10. Name the new partition.
11. Specify which file system format you want to use. If you're running macOS 10.13 or higher, you'll want APFS. If you are running macOS 10.12 or older, you'll want Mac OS Extended.

12. Click apply.

Disk Utility will check the disk and make changes. This will take several minutes.

How to switch partitions

You can switch to the new partition, install the current macOS, and then download and install macOS Catalina from there.

1. Click the Apple icon in the upper-left corner of your screen.

2. Select System Preferences from the drop-down menu.

3. Select Startup Disk.

4. Click the Lock in the lower left corner of the window to unlock and make changes.

5. Enter your system admin password.
6. Click OK.
7. Select your partition drive.

8. Click Restart.

You can also restart your Mac and press the Option Key when you hear the startup chime. This will take you to the Startup Manager and you can select your drive from there.

You will then be asked to install macOS. This will install the latest available macOS onto the partitioned hard drive. You may have to install an older version of macOS before updating it to the more recent version you want to run.

If you are testing a beta version of macOS, you'll first install whatever the current version is. Then, you can then install the macOS beta.

How to download the developer beta of macOS Big Sur

Once you've updated your partitioned Mac with macOS Catalina, you can download and install the developer beta of macOS Big Sur. You need a developer account and probably some patience. Developer betas are often a bit complicated to install. We've got a guide to help you out.

Any questions?

Do you have any questions about installing a partition or downloading a new operating system onto a partitioned drive? Let us know in the comments. If you're having trouble partitioning your hard drive, be sure to check out our forums for help!

Updated June 2020: Updated for the developer beta of macOS Big Sur.

macOS Catalina

Main

We may earn a commission for purchases using our links. Learn more.

Review: Free Your Tea Subscription Box is personalized just for your tastes

The Free Your Tea Subscription Box uses a number of methods to get you your perfect blend of teas each month.

Reinstall from macOS Recovery

macOS Recovery makes it easy to reinstall the Mac operating system, even if you need to erase your startup disk first. All you need is a connection to the Internet. If a wireless network is available, you can choose it from the Wi-Fi menu , which is also available in macOS Recovery.

1. Start up from macOS Recovery

Internal Hard Drive For Macbook Pro

To start up from macOS Recovery, turn on your Mac and immediately press and hold one of the following sets of keys on your keyboard. Release the keys when you see an Apple logo, spinning globe, or other startup screen.

Command (⌘)-R

Reinstall the latest macOS that was installed on your Mac (recommended).

Option-⌘-R

Upgrade to the latest macOS that is compatible with your Mac.

Shift-Option-⌘-R

Reinstall the macOS that came with your Mac, or the closest version still available.

You might be prompted to enter a password, such as a firmware password or the password of a user who is an administrator of this Mac. Enter the requested password to continue.

When you see the utilities window, you have started up from macOS Recovery.

2. Decide whether to erase (format) your disk

You probably don't need to erase, unless you're selling, trading in, or giving away your Mac, or you have an issue that requires you to erase. If you need to erase before installing macOS, select Disk Utility from the Utilities window, then click Continue. Learn more about when and how to erase.

3. Install macOS

When you're ready to reinstall macOS, choose Reinstall macOS from the Utilities window. Then click Continue and follow the onscreen instructions. You will be asked to choose a disk on which to install.

• If the installer asks to unlock your disk, enter the password you use to log in to your Mac.
• If the installer doesn't see your disk, or it says that it can't install on your computer or volume, you might need to erase your disk first.
• If the installer is for a different version of macOS than you expected, learn about macOS Recovery exceptions.
• If the installer offers you the choice between installing on Macintosh HD or Macintosh HD - Data, choose Macintosh HD.

Please allow installation to complete without putting your Mac to sleep or closing its lid. During installation, your Mac might restart and show a progress bar several times, and the screen might be empty for minutes at a time.

If your Mac restarts to a setup assistant, but you're selling, trading in, or giving away your Mac, press Command-Q to quit the 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.

macOS Recovery exceptions

The version of macOS offered by macOS Recovery might vary in some cases:

• If macOS Sierra 10.12.4 or later has never been installed on this Mac, Option-Command-R installs the macOS that came with your Mac, or the closest version still available. And Shift-Option-Command-R isn't available.
• If you erased your entire disk instead of just the startup volume on that disk, macOS Recovery might offer only the macOS that came with your Mac, or the closest version still available. You can upgrade to a later version afterward.
• If your Mac has the Apple T2 Security Chip and you never installed a macOS update, Option-Command-R installs the latest macOS that was installed on your Mac.
• If you just had your Mac logic board replaced during a repair, macOS Recovery might offer only the latest macOS that is compatible with your Mac.

Hard Drive For Macbook

If you can't get macOS Recovery to offer the installer you want, you might be able to use one of the other ways to install macOS.

Other ways to install macOS

Internal Hard Drive For Mac

• You can also install macOS from the App Store or Software Update preferences. If you can't install macOS Catalina, you might be able to install an earlier macOS, such as macOS Mojave, High Sierra, Sierra, El Capitan, or Yosemite.
• Or create a bootable installer disk, then use that disk to install macOS on your Mac or another Mac.