How to create a bootable macOS Big Sur installer drive

How to create a bootable macOS Big Sur installer drive

Apple has a new version of macOS. It’s called Big Sur, and it’s version 11.0. In this article I’ll go over how you can create a bootable macOS Big Sur installation drive. But before I give instructions on how to create the drive, I’ll go over the items you’ll need and how to get them.

These instructions are for the officially released version of macOS Big Sur, not the public/developer beta. It was performed on Macs running macOS Catalina, and again on Big Sur.

Macworld also has bootable-install-drive instructions for:

Get an external drive and maybe an adapter

The macOS Big Sur installer software is over 12GB, so you need a USB external drive that can hold that much data. The drive can be a thumb drive, hard drive, or SSD.

thumb drive IDG

I used this thumb drive to create a macOS Big Sur installer. You can use a thumb drive, external hard drive or SSD. The 32GB drive I used has both USB-C and USB-A (USB 2 speed, however, so it’s slow) connectors and is available on Amazon for about $5.

If you have a 2015 or newer Mac laptop that has USB-C/Thunderbolt 3 ports, you may need Apple’s $19 USB to USB-C adapter. This will allow you to connect a storage device that uses a USB type-A connector. If you don’t have an external drive and you have a USB-C Mac laptop, you could buy the SanDisk Ultra USB Type-C Flash Drive, which has a USB-C connector. You can get model number SDCZ450-016G-G46.

You need to erase the drive and format it to Mac OS Extended (Journaled). You can do this in the Mac’s Disk Utility app, which is in the Applications/Utilities folder. 

format boot drive macos big sur IDG

Format your boot drive using Mac OS Extended (Journaled). My drive was initially formatted as APFS, and an alert appeared saying that the drive could not be used as formatted. 

Get the macOS Big Sur installer software

Big Sur is available through the Apple’s App Store. Click on the Get button on the upper right, and the Software Update system preference will open. Click the Download button. The download may take a while.

macos big sur app store Apple

But after the download is complete and the installer launches, do not click the Continue button. Quit the installer by pressing Command-Q. Then go to your Applications folder and you should find an “Install macOS Big Sur” app. You need to have the app there to make the bootable drive.

Use the Terminal to make a bootable macOS Big Sur installer drive

You’re going to use the Terminal to make your external drive a bootable macOS Big Sur installer. Don’t worry if you’ve never used Terminal before, it’s easy. Here are the instructions.

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