Create a Bootable macOS Montery USB Flash Drive
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This tutorial will show you how to download macOS Montery, copy it to a USB Flash drive, and make it bootable. The Montery USB can be used to perform a clean installation of macOS on any Mac hardware.
Before we begin
You will need a blank USB Flash drive big enough to store the macOS installer which as of writing is (13.66 GB).
If you don’t have a spare USB Flash Drive, I recommend getting a 16 GB SanDisk Ultra Fit* because they are fast, reliable and have a micro form factor. If you’re using a Mac that doesn’t contain USB ports, you will also need an Apple USB-C to USB Adapter*.
Now that you’ve got your hands on a USB Flash Drive and a USB-C to USB Adapter, let’s copy the macOS installer to the drive and make it bootable by following the steps below.
Step 1: Download macOS Installer
The first thing we need to do is download the macOS Installer to your Applications folder. Open the Terminal app and run the following command to download it.
softwareupdate --fetch-full-installer --full-installer-version 12.5.1
Note: you can replace 12.5.1 in the command above with whatever version of macOS you need.
You will notice the output of the command reads
Don’t worry, it’s not installing the update on your Mac. All it’s doing is downloading the installer to your Applications folder.
Wait for the progress to reach 100% and the output to say
Install finished successfully, then you should see the Install macOS Montery app appear in Applications.
Step 2: Prepare USB Flash Drive
Connect the USB Flash Drive to your Mac, open the Disk Utility app, right click on the SanDisk USB Flash Drive then click Erase…
Give the disk a name of SanDisk, select MacOS Extended (Journaled), GUID Partition Map then click Erase.
When the Erase is complete, click Done.
Click on the new SanDisk volume and you will see it has a mount point of /Volumes/SanDisk. Make a note of the mount point because we’ll use it in the command to create the installation media.
Step 3: Copy macOS Installer to USB Flash Drive
Open the Terminal app and change into the directory containing the createinstallmedia utility.
cd /Applications/Install\ macOS\ Monterey.app/Contents/Resources
Run the createinstallmedia utility. Replace the volume with the mount point of your erased disk.
sudo ./createinstallmedia --volume /Volumes/Sandisk
When asked to erase the volume, press y then return.
Ready to start. To continue we need to erase the volume at /Volumes/Sandisk. If you wish to continue type (Y) then press return: y
Wait for the installer to be copied and the disk to be made bootable.
Erasing disk: 0%... 10%... 20%... 30%... 100% Making disk bootable... Copying to disk: 0%... 10%... 20%... 30%... 40%... 50%... 60%... 70%... 80%... 90%... 100% Install media now available at "/Volumes/Install macOS Monterey"
That’s it. You now have a bootable macOS USB Flash drive that you can use to upgrade your Mac or perform a clean install.