How to Create a Bootable macOS USB Installer? (Step-by-Step)

To create a macOS bootable USB flash drive, you must first confirm Mac compatibility, prepare a USB of 12GB or more, and back up the data; after downloading the installer, use Disk Utility to format it into APFS, and then create it through the Terminal command createinstallmedia; after completion, restart and press the power button to select the USB flash drive to start and reinstall the system.

Creating a bootable macOS USB installer is straightforward if you follow the right steps—especially when you're reinstalling macOS, setting up a new Mac, or troubleshooting startup issues.

Check System and USB Requirements

Your Mac must be compatible with the macOS version you want to install. Check Apple's support pages for compatibility before downloading. You'll also need:

• A USB flash drive with at least 12GB of free space (16GB recommended)
• An internet connection to download the macOS installer from the App Store
• macOS Ventura, Sonoma, or Sequoia installed on your Mac (to create the installer)

Note: The USB drive will be completely erased—back up any important data first.

Download the macOS Installer from the App Store

Open the Mac App Store and search for the macOS version you need (eg, “macOS Sequoia”). Click “Get” or “Download”. The installer will appear in your Applications folder as “Install macOS [Name]”. Do not run it—just keep it there.

If the installer disappears after launching, redownload it by holding the Option key and clicking “App Store” > “Check for Unfinished Downloads”.

Prepare the USB Drive Using Terminal

Plug in your USB drive and open Disk Utility. Select the drive (not just the volume), click “Erase”, and format it as APFS or Mac OS Extended (Journaled) , depending on your macOS version (APFS for macOS High Sierra and later). Name it something simple like “MyUSB”.

Then open Terminal and run this command (replace “MyUSB” with your actual drive name and “Install macOS Sequoia” with the correct installer name):

Press Enter, type your admin password (no visible characters), and confirm with Y when prompted. This process takes 15–40 minutes—don't unplug the drive or put your Mac to sleep.

Boot from the USB Installer

Once complete, restart your Mac and immediately hold down the Power button until “Loading startup options” appears. Select the USB drive (it'll show the macOS logo and its name), then click the arrow.

You'll land in macOS Recovery. From there, choose “Reinstall macOS”, select your target disk, and follow the prompts. You can also use Disk Utility here to erase or repair drives before installing.

Basically, it's not complicated—but skipping formatting or mistyping the Terminal command are common pitfalls. Double-check names and permissions, and you'll have a working installer every time.

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