Updated April 04, 2021 · Published March 18, 2021
If you would like to perform a clean install of macOS or update multiple machines, it's a good idea to create a bootable USB installer. The instructions vary just slightly based on which version you're trying to setup.
You can download the latest release of macOS from the App Store. Or you can view the guide on how to download macOS from the command line. After downloading macOS, if the install program automatically runs, do not proceed with the installation, cancel and close it.
Prepare the USB drive
Plugin the USB drive, launch the Disk Utility app, select your USB drive on the left and click the erase button. You can leave the default name Untitled since it will be renamed automatically in the next step. Sometimes erasing the disk fails and requires two attempts to succeed.
Setup the install media
Depending on which version of macOS you are creating a USB installer for, run the appropriate command from the options below. If you changed the name of your volume, be sure to replace the word Untitled with the correct name.
macOS 12 Monterey
sudo /Applications/Install\ macOS\ Monterey.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled
macOS 11 Big Sur
sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled
macOS 10.15 Catalina
sudo /Applications/Install\ macOS\ Catalina.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled
macOS 10.14 Mojave
sudo /Applications/Install\ macOS\ Mojave.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled
macOS 10.13 High Sierra
sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled
macOS 10.12 Sierra
sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ macOS\ Sierra.app
OS X 10.11 El Capitan
sudo /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ OS\ X\ El\ Capitan.app
Reboot into the installer
Hold down the option key immediately after you restart the computer. Then select the USB drive with the installer on it and the macOS installer will start.