Keep a labeled USB drive for your most-used macOS version in your toolkit. It takes 20 minutes to make, but it can save you hours of frustration or a costly trip to the Genius Bar.
Creating a bootable USB installer for macOS is an essential skill for IT professionals, developers, and everyday Mac users. Whether you need to perform a clean install, downgrade your operating system, troubleshoot a corrupted drive, or install macOS on multiple machines, a bootable USB drive is your most reliable tool.
The command syntax varies slightly depending on the macOS version. Here are the most common versions: create mac os x bootable usb installer from dmg
While most online tutorials focus on using the createinstallmedia command with an Install macOS.app downloaded directly from the Apple App Store, what do you do when all you have is a .dmg file? Perhaps you downloaded a beta version, recovered an older OS from an archive, or received an installer from a colleague.
diskutil list Look for your USB drive. It will look something like /dev/disk2 (external, physical) . Note the identifier (e.g., disk2 ). Step 2: Unmount the Drive (But keep it connected) diskutil unmountDisk /dev/disk2 (Replace disk2 with your identifier) Step 3: Write the DMG to the USB Use the dd command (disk duplicator). Be extremely careful. Keep a labeled USB drive for your most-used
sudo /Applications/Install\ macOS\ Sonoma.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume (Replace "Sonoma" with your actual OS name, e.g., "Ventura", "Monterey", or "Big Sur")
sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ macOS\ High\ Sierra.app You don't need to type the whole path. Type sudo (with a space), then drag the createinstallmedia file from the .app (Right-click the app > Show Package Contents > Contents > Resources) into the Terminal window. Then type --volume and drag your USB drive (MyVolume) from the Finder sidebar into the Terminal. Step 4: Follow the Terminal Prompts Terminal will ask for your administrator password (it will not show characters as you type—this is normal). Then it will ask: If you wish to continue type (Y) then press return: Type Y and press Enter. Whether you need to perform a clean install,
The process takes 15–30 minutes. Once you see Copy complete and Done. , your bootable USB is ready. Sometimes, the DMG you have is already a bootable image . This often happens with older macOS versions (Lion, Mountain Lion, Mavericks) or custom recovery DMGs. In this case, you don't need an installer app; you write the DMG directly to the USB.