How To Make Mac OS Big Sur System Boot USB Flash Disk

Making a bootable Mac OS Big Sur USB flash drive is a fast, convenient and clean way to install a new copy of Mac OS on a Mac computer. This article will tell you how to do it.

1. The Requirement Of The USB Flash Disk.

1. Before you can create a macOS boot USB flash disk, you must have a USB flash disk.
2. USB port type should be USB-C.
3. USB disk space should be bigger than 16G.
4. Ensure that the USB flash drive does not contain important data because it will be formatted during the process and all the data in it will be erased.

2. Download The macOS Big Sur.

1. Open App Store and search the keyword macOS Big Sur in the search box.
2. Then you can download it to your local MacBook.
3. After the download is complete, do not start the installation. If the installation program automatically runs, press Command + Q to exit the installation program.
4. Open The downloaded dmg file and move the .app file in it to the Finder —> Applications folder.

3.  Make macOS Big Sur Boot Disk Steps.

1. Connect the USB flash disk to your mac computer.
2. Open the Finder —> Applications —> Utilities —> Disk Utility.
3. Select the USB flash disk, click the Erase button to format it, give it a name for example Vol1.
4. Select the Mac OS Extended (Journaled) in the Format select list.
5. Select the GUID Partition Map from the Schema select list.
6. Click the Erase button to erase it.
7. Open a terminal and run the command sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia –volume /Volumes/Vol1.
8. When you see the output text like below, it means the installation success.

   $sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/Vol1
   [Password:
   Ready to start.
   To continue we need to erase the volume at /Volumes/Vol1.
   If you wish to continue type (Y) then press return:y
   Erasing disk: 0%... 10%... 20%... 30%... 100%
   Copying to disk: 0%... 10%... 20%... 30%... 40%... 50%... 60%... 70%... 80%... 90%... 100%
   Making disk bootable...
   Install media now available at "/Volumes/Install macOS Big Sur"

9. The speed of copying to disk depends on the speed of your USB flash disk.
10. When it comes to making disk bootable, don’t think it’s finished, it may take a long time. You need patients.

4. Install macOS Big Sur From USB Disk.

1. Connect the prepared Mac OS Big Sur boot USB flash disk into the Mac.
2. Restart the Mac, then press and hold the “option” key until “install Big Sur” appears, and then release the option key.
3. Click “install Big Sur” to start installing the macOS Big Sur system.