Creating a bootable macOS Big Sur USB drive is a quick and clean way to install a fresh copy of macOS on your Mac. This practical guide is valid for both the public and developer beta version of macOS Big Sur, and will also work with the final version of Big Sur after its release later this year. Just follow our step-by-step guide for full details.
Before you begin, you need to get a USB flash drive. Because every modern Mac supports USB-C, and some Macs only have USB-C, I recommend buying a USB drive with a USB-C connector.
The other thing to keep in mind is that you will want to get a USB drive with at least 8 GB of storage space. Of course, it will not hurt to have more storage space. I still recommend this SanDisk Ultra Dual Drive USB Type-C Flash Drive. Not only is it affordable, but there are both USB-A and USB-C connections, which make the drive easy to connect to any Mac.
Make sure there is nothing important you need on the drive, because all the content will be deleted. I recommend checking the contents and then formatting the drive as macOS Extended Journaled (HFS +) via Disk Utility. Note that APFS formatted drives cannot be used to create the MacOS Big Sur USB installer.
macOS Big Sur USB installation video tutorial
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How to make a bootable MacOS Big Sur USB installation drive
Step 1: Download macOS Big Sur. After Big Sur launches later this year, you can download it directly from the Mac App Store. Until then, you can download the macOS Big Sur developer beta from Apple’s developer portal, or download the macOS Big Sur public beta via Apple’s public beta site.
Step 2: After downloading macOS Big Sur, the installer will start automatically. Close the installer.
Step 3: Open Finder → Applications. Right click Install macOS Big Sur → View the contents of the package.
Step 4: Open Content → Resources.
Step 5: Start a new terminal window by going to Applications → Tools → Terminal.
Step 6: Type
sudo followed by a space in the terminal window.
Step 7: Drag createinstallmedia to the terminal window from the resource folder specified in step 4.
Step 8: Type
--volume followed by a space.
Step 9: Open Finder → Go → Go to folder …
Step 10: I ‘Go to folder ‘ box type / Volume and click the Go button.
Step 11: Connect a USB flash drive to your Mac; it should appear in the Finder window.
Step 12: Drag the volume of the USB flash drive into the terminal window.
Step 13: Print Return key on the keyboard to enter the entire Terminal command, and enter your password when prompted.
Step 14: When prompted, enter a “y” and press Return key on the keyboard to enter.
Terminal can request access to files on the removable volume.
Step 15: The installation process begins with cleaning the contents of the connected USB drive. Afterwards, the installation files are copied to the drive. Because this process takes a few minutes to complete, you need to be patient throughout the installation process.
Uses MacOS Big Sur USB installer
Creating the USB installation drive is easy, but using it can be challenging for users running Macs with Apple T2 Security chips. The steps mentioned guide you through the basic process of creating the installer, but the review of the video goes even more in depth.
Details on how to enable boot from external / removable media via recovery mode are explained, along with the instructions on secure boot settings which I found useful. Be sure to watch the entire video for step-by-step details on using the USB installation drive after creating it by following the steps described above.
When you install macOS Big Sur, you have several options at your disposal.
- You can choose to upgrade your existing macOS installation, go from macOS Catalina or earlier versions of macOS to Big Sur.
- You can delete the existing installation and start from scratch.
- You can create a separate APFS volume and install macOS Big Sur there if you want to keep macOS Catalina. Read and see our tutorial on creating separate APFS volumes for macOS Big Sur for more information.
Although there are Internet recovery options for reinstalling MacOS, I like the idea of keeping a MacOS USB installer around. This makes it easy to install macOS Big Sur on any compatible Mac, even if you have not downloaded the MacOS Big Sur installer on that computer. This is especially nice if you manage multiple Macs at home.
Do you make it a habit to create bootable MacOS USB installation drives? Sound off in the comments with your thoughts on the matter.
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