How to Make a Bootable Flash Installer of OS X or macOS

The sudo command will ask for your password. As you type it will not appear. This is normal. Just enter it and press return to create the boot drive.

How to make bootable OS X Yosemite USB flash drives and other media

How do you erase your Mac hard drive and install OS X Yosemite without a startup disk? Normally the answer would be to boot into recovery mode. But what if you need to partition the hard drive, wiping the recovery partition? You need a bootable OS X Yosemite installer. Here’s how to make one using Apple’s built-in boot drive creation tool.

What You Need

1. The 5GB OS X Yosemite installer app that downloads into your Applications folder when you first install it via the Mac App Store. The file name is Install OS X Yosemite. After you upgrade to Yosemite, this file is deleted. So you have to quit the installer once it appears in order to keep this file.
2. A flash drive, external hard disk, SD card, or the like, with at least 8GB of capacity.
3. Your Mac user account must be an Administrator. If it isn’t, go to Users & Groups in System Preferences and assign Administrator to your user account. You can change it back to a standard user when you’re finished. You can also sign in to your Mac as the administrator to create the bootable drive.

Step 1: Format Your Drive

First, you must partition and erase the drive so that it can be bootable. To do this, launch Disk Utility and choose the destination drive in the drive list (left column). On the right, in the Erase tab, choose to format the drive as Mac OS Extended (Journaled). These are the defaults, so just confirm the settings.

Next go to the Partition tab and under Partition Layout choose “1 Partition” in the dropdown menu. Change the name from “Untitled 1” to “Untitled”. This is so that the Terminal command below will find the drive. Once the process is complete, the drive name will be “Install OS X Yosemite”.

Click the “Options” button. In the dialog that appears, choose “GUID Partition Table” as the partition scheme, then click “OK”. Again, this is the default, so just confirm the setting.

Finally, click “Apply” to confirm the settings and prepare the drive.

Step 2: Make the Drive a Yosemite Boot Installer

In a single command you’ll create the bootable install drive. Pretty sweet! To do this, launch Terminal and enter the following command. Note, this assumes that you haven’t moved the installer out of your Applications folder. If you have, simply replace “/Applications” with the location of the installer:

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

The sudo command will ask for your password. As you type it will not appear. This is normal. Just enter it and press return to create the boot drive.

During installation, you’ll see a progression of status messages.

Erasing Disk: 0%. 10%. 20%. 30%. 100%. Copying installer files to disk. Copy complete. Making disk bootable. Copying boot files. Copy complete. Done. 

Wait until you see a status of “Done.” When you do, you can safely eject the drive and quit Terminal.

Step 3: Start Up from the Install Drive

If you open the new bootable drive in the Finder, you’ll notice that it appears empty, other than the Install OS X Yosemite app. No worries. The boot files are hidden, and the installer app allows you to upgrade without booting from the drive if you don’t need to.

To boot from this new installer, shut down the Mac, plug in the bootable drive, and hold down the option key while powering back up. You should eventually see a series of bootable drives. Click on the one named “Install OS X Yosemite” and press the return key.

Article last updated on 4/21/2018

How to Make a Bootable Flash Installer of OS X or macOS

Tom Nelson is an engineer, programmer, network manager, and computer network and systems designer who has written for Other World Computing,and others. Tom is also president of Coyote Moon, Inc., a Macintosh and Windows consulting firm.

Updated on July 11, 2022
Reviewed by

Jerrick Leger is a CompTIA-certified IT Specialist with more than 10 years’ experience in technical support and IT fields. He is also a systems administrator for an IT firm in Texas serving small businesses.

What to Know

• You’ll need: OS X or macOS installer and a 12+ GB USB flash drive (formatted as “Mac OS Extended”).
• Find installer in Applications > plug in flash drive > rename flash drive > open Applications or Utilities folder.
• Next: Open Terminal > enter OS-specific command > enter admin password when asked >Y to confirm.

This article explains how to create a bootable installer for OS X or macOS using a USB flash drive.

This article addresses the creation of a bootable USB drive for OS X Mavericks and later as well as macOS. macOS refers to Apple operating systems starting with version numbers 10.12 and later. OS X describes version numbers 10.8 through 10.11.

Lifewire / Alex Dos Diaz

What You Need

First, you need the OS X or macOS installer on your Mac. Ideally, download the installer, but don’t use it. When you download and use the OS X or macOS installer, the installer deletes itself as part of the installation process. If you’ve already installed OS X or macOS, redownload the installer.

If you download the installer and find that it starts up on its own, quit the installer the way you would any other Mac app.

After it is downloaded, the installer resides in the Applications folder. It is called “Install OS X [your version]” or “Install macOS [your version].”

You’ll also need a USB flash drive. Make sure that it has at least 12 GB of available storage and is formatted as Mac OS Extended.

It’s also important that your Mac meets the minimum requirements for the OS you’re installing. Apple’s website offers the exact system requirements for each version.

How to Use the Createinstallmedia Terminal Command

From OS X Mavericks forward, in the installer packages is a hidden command that you can enter into Terminal to create a bootable copy of the installer.

This Terminal command, called createinstallmedia, creates a bootable copy of the installer using any drive connected to your Mac. This example uses a USB flash drive. Here’s how to do it:

The createinstallmedia command erases the content of the USB drive, so back up any data on the drive if it’s important.

1. Locate the Mac OS installer file in the Applications folder.

Rapid double-clicking the name of a drive can open that drive in a window on Finder, so if this step isn’t working for you, try clicking once on the file name, pausing for a second, and then clicking a second time.

Alternatively, enter Terminal into Spotlight Search to quickly start up the utility.

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

For macOS Mojave:

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

For macOS High Sierra:

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

For OS X El Capitan

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

For OS X Yosemite:

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

For OS X Mavericks:

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