Making a bootable macOS Big Sur USB drive is a quick and clean way to install a fresh copy of macOS on your Mac. This hands-on tutorial is valid for both the public and developer beta versions of macOS Big Sur, and will also work with the final version of Big Sur upon its release later this year. Simply follow our step-by-step guide for the full details.
USB Flash drive
Before you begin, you’ll need to acquire a USB flash drive. Because every modern Mac supports USB-C, and some Macs only feature USB-C, I recommend purchasing a USB drive with a USB-C connector.
The second thing to keep in mind is that you’ll want to get a USB drive with at least 8GB of storage space. Of course, having more storage won’t hurt. I still recommend this SanDisk Ultra Dual Drive USB Type-C Flash Drive. Not only is it super-affordable, but it comes both USB-A and USB-C connections, which allows the drive to connect to any Mac with ease.
Make sure that there’s nothing important that you need on the drive, because the full contents will be deleted. I recommend checking the contents, and then formatting the drive as macOS Extended Journaled (HFS+) via Disk Utility. Keep in mind that APFS-formatted drives cannot be used to create the macOS Big Sur USB installer.