If you’re downloading the installer from within macOS Tahoe, you’ll see a pop-up when the download completes, telling you that the installer can’t be run from within that version of macOS. Since we’ll be running it from its own USB stick, you can safely ignore this message.
Settings to format your USB disk to prepare it for the macOS installer.
Andrew Cunningham
Settings to format your USB disk to prepare it for the macOS installer.
Andrew Cunningham
A 64GB disk is large enough to hold two or three macOS installers simultaneously.
Andrew Cunningham
A 64GB disk is large enough to hold two or three macOS installers simultaneously.
Andrew Cunningham
Settings to format your USB disk to prepare it for the macOS installer.
Andrew Cunningham
A 64GB disk is large enough to hold two or three macOS installers simultaneously.
Andrew Cunningham
While the installer is downloading, install and prepare your USB drive. Open Disk Utility, click the View button and select “Show All Devices”. Click the root of your USB drive under the “External” header in the left sidebar, and click the Erase button in the upper-right control area.
Change the name of the disk to whatever you want—I use “MyVolume” so I don’t have to change Apple’s sample Terminal commands when copying the installer files—and make sure the format is set to Mac OS Extended (Journaled) and the scheme is set to GUID Partition Map. (This is not an error; the macOS installer still wants the HFS+ file system instead of APFS.)
The handy thing is that if you have a large USB drive, you can create installers for multiple macOS versions by partitioning the disk with the Partition button. A 64GB drive split into three ~21GB partitions can boot Tahoe, Sequoia, and another older or future macOS version; I just split it into two sections so I can boot the Sequoia and Tahoe installers from the same drive.
Our macOS 15 Sequoia is running Terminal commands to create the boot drive.
Credit: Andrew Cunningham
Our macOS 15 Sequoia is running Terminal commands to create the boot drive.
Credit: Andrew Cunningham
Once the Sequoia installer is in your Applications folder, run a Terminal command to copy the installer files. Apple has commands for every version of macOS on this page. Use this for Sequoia:
sudo /Applications/Install\ macOS\ Sequoia.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume
If you named the USB drive something other than MyVolume when you formatted it, change the name in the command as well. Note that names with spaces require a backslash before each space.
The terminal will ask you for your password and ask you to type Y to confirm. It will then reformat the drive and copy the files. The time this takes will vary depending on the speed of the USB drive you are using, but for most USB 3 drives, it should only take a few minutes to create the installer. When the Terminal commands are finished running, leave the disk in place and turn off your Mac.
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