How to create a bootable USB for Mac

Every computer may not boot up every once in a while, which can be irritating because it prevents you from getting into the system to view exactly what the problem is. The good news is there’s an easy(ish) workaround!

By booting from an external drive, like a USB for example, you can diagnose certain issues by accessing the internal drive with minimal effort.

That being said, many new Mac laptops don’t have USB-A ports, so it’s a good idea to obtain an external port that connects to a USB-C (USB Type C) port to really make the process easy-ish.

What is a bootable USB?

A bootable USB is a flash drive that allows you to both install an operating system (OS), and boot the computer from the external USB drive instead of using the computer’s hard drive.

Whether a computer is brand new or is unusable due to a compromised OS, you can use a bootable USB to install a fresh operating system. You can run an OS installer like Windows, OSX, Mac, or specific versions of Linux from a bootable USB drive.

For macOS specifically, you can use a bootable USB to install macOS Sonoma, Ventura, Monterey, Big Sur, Catalina, Mojave, High Sierra, or El Capitan.

What you need to create a bootable USB for Mac

In order to create a Mac USB bootable installer, there are two things you need to have:

• 1. A USB external drive that:
• Can plug into the Mac device. Most Macs only have USB-C ports, whereas many USB-s are only USB-A compatible, so you’d need an adapter.
• Contains at least 32GB of available storage for the newer macOS versions like Sonoma and Ventura. (Note: for most older versions of macOS, 16GB will be enough)

• 2. At least 32GB of available storage (or maybe less, depending on the macOS you want to use) on the computer you wish to install the OS on.

NOTE: Be aware that all existing data that you currently have stored on the USB drive you plan to use will be deleted, due to the temporary nature of a bootable USB for Mac. So be sure you’re not also storing other important files on the USB you will use, or else they will be deleted.

How to download the installation files for your bootable USB

In order to create your USB bootable flash drive, you’ll first need to download the installation files. You can find and download them from either from the “Software Update” section within the System Preferences app, or from the Mac App Store.

For most people, downloading the installation files from the Mac App Store tends to be the less complicated option of the two, though they both work.

How do I create a bootable USB drive for Mac?

• Step 1: Download the macOS installer of the version you plan on installing on the USB flash drive. This should automatically download to your Applications folder as an app named “Install macOS [version name]”. 
• Make sure that the installer is located in your “Applications” folder before continuing, as this is where the Terminal command to download the OS will attempt to find the app. The installer is generally automatically located here after install, but it’s a good idea to double-check before going on. Also make sure that it’s .app, instead of .dmg or .pkg.
• Step 2: Insert the USB drive into the computer.
• Step 3: Using “command (⌘) + spacebar, find and open “Disk Utility”. Alternatively, you can open “Finder”, go to the “Applications” folder, scroll down to “Utilities”, and then open “Disk Utility”. 
• Step 4: Once you’ve opened “Disk Utility”, you should see your USB listed under “External” on the left side. Click on your USB, then click on the “Erase” button at the top. It should bring up new fields for “Name,” “Format,” and “Scheme.”
• Rename the drive, you’ll need to remember it when you enter a command into Terminal. For our example commands (if you just want to copy and paste), then you can rename your USB to “MyVolume”. But if you prefer, you can use a name that’s more descriptive, such as “Booting macOS.”
• Select “macOS Extended (Journaled)” as the format.
• Step 5: Next we’re going to open up Terminal, which is also located in the “Utilities” folder of the Applications folder. Now we get to actually installing the macOS installer directly on the USB drive.
• Step 6: Run the Terminal command that corresponds to your downloaded macOS version listed below. Please note that these commands assume that the installer is located in your Applications folder named “Version.app”, and that your USB is named “MyVolume”. If you used a different name for your USB drive, you’ll have to replace “MyVolume” with the correct name in the command. And if your installer is named something different, you’ll have to adjust that within the command as well.

Monterey: sudo/Applications/Install\macOS\Monterey.app/Contents/Resources/createinstallmedia –volume/Volumes/MyVolume

Big Sur: sudo/Applications/Install\macOS\Big\Sur.app/Contents/Resources/createinstallmedia–volume/Volumes/MyVolume

Catalina: sudo/Applications/Install\macOS\Catalina.app/Contents/Resources/createinstallmedia –volume/Volumes/MyVolume

Mojave: sudo/Applications/Install\macOS\Mojave.app/Contents/Resources/createinstallmedia –volume/Volumes/MyVolume

High Sierra: sudo/Applications/Install\macOS\High\Sierra.app/Contents/Resources/createinstallmedia –volume/Volumes/MyVolume

El Capitan: sudo/Applications/Install\OS\X\El\Capitan.app/Contents/Resources/createinstallmedia –volume/Volumes/MyVolume –applicationpath /Applications/Install\ OS\ X\ El\Capitan.app

After running the command, you may get an alert that Terminal would like to access files, so make sure to click OK if this happens.

Once this stage is complete, the volume should have the same name as the installer you downloaded.

You can now quit Terminal and eject your USB. And that’s it! You now have a bootable USB for macOS, that you can use to reboot and install the specified macOS to another computer.

Can you install Mac OS from USB?

You absolutely can install macOS from a USB drive! Using your newly created bootable macOS USB drive, just follow the steps outlined below to install macOS on the computer in question. In fact, you can actually put multiple OS on a single flash drive.

How to use the bootable USB for Mac

A bootable installer doesn’t download macOS from the internet, but it actually does require an internet connection. An internet connection is required to fetch firmware and obtain other information specific to your Mac or Macbook.

The first step is to figure out whether your Mac uses an Intel processor or an Apple silicon processor. This is quite easy to do as long as you’re able to access the computer. Just hit the Apple icon in the top left corner, then “About this Mac”, and look for the line that says “Chip” or “Processor”. If it says M1 or M2, your Mac uses Apple Silicon. If it says “Intel”, your Mac has an Intel processor.

Based on this information, follow the steps as instructed by Apple:

If your device is equipped with Apple silicon

• Turn off your Mac or MacBook.
• Plug the bootable USB into your Mac while still in range of the internet. Ensure that the device is compatible with the version of macOS you’re installing.
• Turn on the computer and hold the power button until you see the startup options window.
• Select the volume containing the bootable installer, then click “Continue”.
• When the macOS installer opens, follow the instructions it will present to you.

If your device is equipped with an Intel processor

• Turn off your Mac or MacBook.
• Plug the bootable USB into a Mac while still in range of the internet. Ensure that the device is compatible with the version of macOS you’re installing.
• Turn on your computer, and then immediately press and hold the Option (Alt) ⌥ key.
• Release the Option key when you see a dark screen showing your bootable volumes.
• Select the volume containing the bootable installer, after which you should press Return.
• Select Install macOS (or Install OS X) from the Utilities window, then click Continue and follow the instructions it will present to you.

You can expect the entire installation process to take about 10 minutes, give or take, depending on the speed of your hardware.

Can I use Rufus to make a bootable USB for Mac?

Unfortunately, you can’t use Rufus to make a bootable USB for Mac. Rufus is a free and open-source app that helps format and create bootable USB flash drives. While making bootable USBs may appear to be its main purpose, Rufus can’t interpret the boot loader, which is why you can’t use Rufus to make a bootable USB compatible with Mac. But luckily using the instructions laid out in today’s blog post, you can easily make a USB boot for your Mac.

Can you make a bootable usb for mac on windows?

While you can’t use Rufus to make a bootable USB for Mac on a Windows computer, there are other tools that make this possible. A few of the most highly recommended applications to do this are TransMac or UUByte DMG Editor. 

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