Creating a Bootable OS X/macOS USB Installer

Creating a bootable USB installer for macOS is an essential skill for any Mac user. Whether you're performing a clean install, troubleshooting a problematic Mac, or installing macOS on multiple machines, having a bootable USB installer can save you time and bandwidth.

Requirements

• An 8GB USB drive (16GB+ recommended for newer macOS versions)
• A Mac running OS X 10.6.8 (Snow Leopard) or newer
• Fast internet connection to download the installer
• The macOS installer application from the Mac App Store

Step 1: Download the macOS Installer

Download your desired macOS version from the Mac App Store. The installer will appear in your Applications folder once the download is complete.

Direct Mac App Store Links

Click the links below to open the Mac App Store and download the installer directly:

• macOS Sequoia
• macOS Sonoma
• macOS Ventura
• macOS Monterey
• macOS Big Sur
• macOS Catalina
• macOS Mojave
• macOS High Sierra
• macOS Sierra
• OS X El Capitan
• OS X Yosemite - No longer available on Mac App Store
• OS X Mavericks - No longer available on Mac App Store

Note: Some older macOS versions may not be available in all regions or may require you to have previously "purchased" them with your Apple ID. If a link doesn't work, you can also use Apple's support page to download older versions.

Step 2: Prepare Your USB Drive

1. Connect your USB drive to your Mac
2. Open Disk Utility (Applications → Utilities → Disk Utility)
3. Select your USB drive from the sidebar
4. Click Erase
5. Choose the following settings:
   • Format: Mac OS Extended (Journaled)
   • Scheme: GUID Partition Map (if available)
   • Name: Name it after the OS version (e.g., "Monterey", "Ventura", etc.)
6. Click Erase to format the drive

Step 3: Create the Bootable Installer

Open Terminal (Applications → Utilities → Terminal) and run the appropriate command for your macOS version:

macOS Sequoia (15) - 2024

sudo /Applications/Install\ macOS\ Sequoia.app/Contents/Resources/createinstallmedia --volume /Volumes/Sequoia --nointeraction

macOS Sonoma (14) - 2023

sudo /Applications/Install\ macOS\ Sonoma.app/Contents/Resources/createinstallmedia --volume /Volumes/Sonoma --nointeraction

macOS Ventura (13) - 2022

sudo /Applications/Install\ macOS\ Ventura.app/Contents/Resources/createinstallmedia --volume /Volumes/Ventura --nointeraction

macOS Monterey (12) - 2021

sudo /Applications/Install\ macOS\ Monterey.app/Contents/Resources/createinstallmedia --volume /Volumes/Monterey --nointeraction

macOS Big Sur (11) - 2020

sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/Big\ Sur --nointeraction

macOS Catalina (10.15) - 2019

sudo /Applications/Install\ macOS\ Catalina.app/Contents/Resources/createinstallmedia --volume /Volumes/Catalina --nointeraction

macOS Mojave (10.14) - 2018

sudo /Applications/Install\ macOS\ Mojave.app/Contents/Resources/createinstallmedia --volume /Volumes/Mojave --nointeraction

macOS High Sierra (10.13) - 2017

sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/High\ Sierra --nointeraction

macOS Sierra (10.12) - 2016

sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/Sierra --applicationpath /Applications/Install\ macOS\ Sierra.app --nointeraction

OS X El Capitan (10.11) - 2015

sudo /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia --volume /Volumes/El\ Capitan --applicationpath /Applications/Install\ OS\ X\ El\ Capitan.app --nointeraction

OS X Yosemite (10.10) - 2014

sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/Yosemite --applicationpath /Applications/Install\ OS\ X\ Yosemite.app --nointeraction

OS X Mavericks (10.9) - 2013

sudo /Applications/Install\ OS\ X\ Mavericks.app/Contents/Resources/createinstallmedia --volume /Volumes/Mavericks --applicationpath /Applications/Install\ OS\ X\ Mavericks.app --nointeraction

Important Notes

• Password Required: You'll be prompted to enter your administrator password when running the sudo command
• Time Required: The process typically takes 20-30 minutes depending on your USB drive speed
• Warning Messages: You may see warnings about erasing the disk - this is normal and expected
• Older Versions: For macOS Sierra (10.12) and earlier, the --applicationpath parameter is required
• Newer Versions: Starting with High Sierra, the --applicationpath parameter was deprecated and should be omitted

Step 4: Using Your Bootable Installer

To boot from your newly created USB installer:

1. Connect the USB drive to the Mac you want to install macOS on
2. Turn on or restart the Mac
3. Immediately hold down the Option (⌥) key
4. Release the Option key when you see the Startup Manager window
5. Select your USB installer drive
6. Click the arrow or press Enter to boot from it

Troubleshooting

"This copy of the Install macOS application can't be verified"

This error usually occurs when your system date is incorrect. To fix it:

1. Boot into the installer
2. Open Terminal from the Utilities menu
3. Set the correct date using: date mmddHHMMYYYY
   • Format: month, day, hour (24h), minute, year
   • Example for Dec 31, 2024 at 3:30 PM: date 123115302024

USB Drive Not Showing in Startup Manager

• Ensure the USB drive is properly formatted with GUID Partition Map
• Try a different USB port
• Some older Macs may not support booting from USB 3.0 drives

Installation Fails or Hangs

• Verify the installer app isn't corrupted by re-downloading it
• Try a different USB drive
• Reset NVRAM/PRAM by holding Command-Option-P-R during startup

Alternative Method: Using Disk Utility

For macOS Big Sur and later, you can also create a bootable installer using Disk Utility's Restore feature:

1. Mount the installer DMG (found inside the .app bundle at Contents/SharedSupport/)
2. Open Disk Utility
3. Select your USB drive
4. Choose Edit → Restore
5. Select the mounted installer volume as the source
6. Click Restore

Conclusion

Having a bootable macOS USB installer is invaluable for system maintenance and troubleshooting. Keep your installer updated with the latest macOS version, and consider creating multiple installers if you support different Mac models with varying OS requirements.

Remember to store your bootable USB drives in a safe place and label them clearly with the OS version for easy identification.