Learn how to get macOS Sequoia on a USB thumb drive and use it to install macOS 15 on multiple Macs without needing to download the large macOS file each time.
Things needed
- A USB thumb drive that’s at least 16 GB (use a faster USB 3.0 drive if you have one)
- Reliable Internet connection on your Mac
- An hour of free time
- The Mac you’re using must officially support macOS Sequoia
Steps involved
The entire process involves four steps:
- Download the macOS Sequoia installer
- Format USB thumb drive as Mac OS Extended
- Use Terminal to create a macOS 15 bootable installer
- Use the macOS Sequoia USB bootable installer to install it on various Macs
Step 1: Download the macOS Sequoia installer
1) Search for macOS Sequoia on the Mac App Store or click this direct link. Then, click Get, followed by Download. We have explained this entire process in our guide on installing macOS Sequoia on a different partition.
Alternatively, you can open Terminal, enter softwareupdate --list-full-installers and hit the return/enter key. The Terminal will show a list of all macOS version installers you can download and install on your Mac.
To download the macOS Sequoia installer, type this command in the Terminal and hit the return key: softwareupdate --fetch-full-installer --full-installer-version 15.5
Obviously, you can change 15.5 to another macOS Sequoia build to get an older/newer version (as available). Terminal will start scanning and then downloading macOS Sequoia.
Note: You can also download and install macOS Sequoia using this direct Apple link. Learn more about it in our macOS Tahoe guide.
2) After macOS Sequoia is downloaded, go to your Mac’s Launchpad or the Applications folder, and you’ll see the macOS Sequoia installer here. Now, move to step 2. If you don’t see it, you can’t proceed further. In that case, try the above steps again.
Step 2: Format the USB thumb drive as Mac OS Extended
Terminal will automatically format the drive in the next step, but it’s recommended to do it beforehand so that it’s quicker for Terminal and some random errors don’t fail the entire process.
1) Connect your thumb drive to your Mac.
2) Open Disk Utility and select this thumb drive.
3) Click Erase.
4) You can enter any name, as it doesn’t matter and will be overwritten by Terminal in step 3. But I recommend naming it Sequoia. This way, you won’t have to edit the Terminal command in the next step and can simply copy & paste the command I used.
5) In the Format box, select Mac OS Extended (Journaled). And if you see Scheme, select GUID Partition Map.
6) Finally, click Erase and make sure it’s successful. If not, try erasing it again.
Step 3: Use Terminal to create a macOS 15 bootable installer
1) Open Terminal on your Mac.
2) Now, enter sudo /Applications/Install\ macOS\ 15\ Beta.app/Contents/Resources/createinstallmedia --volume /Volumes/Sequoia and hit the enter/return key.
Note: If the process fails now or in later steps, consider going to the Applications folder in Finder and renaming the Install macOS 15 beta file to just Sequoia. Next, change the Terminal command appropriately to sudo /Applications/Sequoia.app/Contents/Resources/createinstallmedia --volume /Volumes/Sequoia and retry.
3) Enter your Mac’s password and hit the enter/return key. Note that when you type the password in Terminal, it doesn’t show that you’re typing.
4) You’ll now see ‘To continue we need to erase the volume at…’ permission. Type Y in Terminal and hit the enter/return key again.
Click OK if you see a popup saying, “Terminal would like to access files on a removable volume.”
Note: If you see an “IA app name cookie write failed. The bless of the installer disk failed” error in Terminal, go to System Settings > Privacy & Security > Full Disk Access and turn on the switch next to Terminal. After quitting and reopening the Terminal app, follow the above steps again.
5) All done! Now, Terminal will:
- Erase the disk
- Copy essential files
- Copy the macOS RecoveryOS
- Make disk bootable
- Copy essential files to disk
While it happens, try to keep your computer awake and refrain from doing intensive tasks. This will ensure Terminal can work without issues.
It will take a long time to finish. Remember not to unplug your thumb drive after 100% copying is done. Rather, eject it safely only after you see the “Install media now available at…” line in Terminal.
Step 4: Use the macOS Sequoia USB bootable installer
Before you begin:
- You should know whether your Mac has Apple silicon (M1, M2, M3, M4, etc.) or an Intel processor. After that, follow the appropriate steps below.
- Make sure your Mac supports macOS Sequoia.
- While installing macOS from a USB drive, the huge macOS file isn’t downloaded from the internet. But still, your Mac must be connected to the internet to get firmware and other essential information.
- Open this iDB post on your phone or another computer and shut down your Mac where you want to install macOS Sequoia. Next, follow the steps below.
Mac with Apple silicon
Follow these steps to use a bootable macOS Sequoia Installer if your Mac has Apple silicon:
1) Plug in the bootable USB drive installer to your Mac.
2) Press the power button and continue pressing it until you see Loading startup options on the screen.
3) You’ll now see the available bootable volumes. Select the drive with the bootable installer and click Continue. Follow the instructions in the macOS installer window to install macOS Sequoia on your Mac.
Intel processor
Here’s how to use a bootable macOS Sequoia Installer if your Mac has an Intel processor:
1) Plug in the bootable USB drive installer to your Mac.
2) Turn on your Mac and immediately press and hold the Option key. Stop pressing the Option key when you see the black screen with your Mac’s available bootable volumes.
3) Select the bootable installer drive and press the return key or click the up arrow.
4) After choosing the language, select Install macOS from the Utilities window and click Continue. Now, follow the on-screen instructions.
This is how you can create and use the macOS Sequoia USB installer to get macOS 15 on your Mac.
For more, check out how to install macOS Tahoe 26 on a USB drive or install macOS Tahoe on a second volume of your Mac.