As a mac user, there may come a time when you’d want to reinstall macOS on your computer- say something goes wrong with your machine or you just want to have a fresh start. Well, if you do want to install macOS on your computer, I would suggest you to do it via USB.
Here are a couple of reasons why:
You can do it offline – Installing macOS via USB will allow you to do it offline meaning that you wouldn’t need to wait for the re-downloading of the entire macOS installer, which could take a while depending on your internet speed.
You can do it faster – All it takes to reinstall macOS on a computer is to simply plug in the USB drive and get the mac to boot via external source (your thumb drive).
You can do it anytime you want – As long as you keep the USB drive bootable with the macOS installer in it, you can reformat and reinstall the macOS again anytime you want.
Before we get started, here are some prerequisites that you need to take into consideration. Make sure you’ve got all of them as it will make the entire process much faster.
A thumb drive, aka USB flash drive, is what you would need for this to work. I would suggest you to get the one with a capacity of 16 GB or higher to store the macOS installer file.
Whether you want to reinstall the latest macOS Catalina, or you want to revert or downgrade to Mojave, or High Sierra, you will need to decide now as it dictates which installer file you will be downloading in a second.
Ready? Let’s get started.
Let’s start with this first as the downloading of the macOS installer file may take a while.
Click on the following links to choose which macOS’s installer file you would like to download:
Note: Clicking on any of the above links will launch the App Store, which brings you to the official download page of the specific macOS.
Next, click Get > Download to initiate downloading.
Note: Download will take around 10 minutes to a few hours, depending on your internet connection.
While waiting for the download, let’s move on to the next step – formatting your thumb drive.
If you are using an existing thumb drive, make sure to backup all existing data inside as we are going to format the thumb drive, getting it ready and compatible for the bootable mac installer.
Note: The entire process will take around 5 minutes, depending on the capacity of your thumb drive.
To proceed, you will need to ensure the downloading of the macOS installer (step 1) has completed.
VOLUMN_NAMEto your thumb drive’s new name and paste it inside Terminal.
sudo /Applications/Install macOS Catalina.app/Contents/Resources/createinstallmedia --volume /Volumes/VOLUMN_NAME
sudo /Applications/Install macOS Mojave.app/Contents/Resources/createinstallmedia --volume /Volumes/VOLUMN_NAME
sudo /Applications/Install macOS High Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/VOLUMN_NAME
sudo /Applications/Install OS X El Capitan.app/Contents/Resources/createinstallmedia --volume /Volumes/VOLUMN_NAME --applicationpath /Applications/Install OS X El Capitan.app
If you are downloading Mojave installer, and your thumb drive’s name is Untitled, your command would be the following. Take note of the changes in bold.
sudo /Applications/Install macOS Mojave.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled
When you see “Install media now available at…." in Terminal, that means the entire process is done.
You can then Eject your thumb drive and quit the Terminal app.
If you have managed to follow through till this step, this means you have created a bootable thumb drive with macOS installer. Now, let’s give it a test to see if it works.
Double click “Macintosh HD” to return to your Mac, or “Install macOS …” to install your Mac afresh, but that’s another topic.
Hope this guide will help you in installing macOS through USB. Let us know about your experience in the comment section below.