Make Macos Usb Installer


Sep 20, 2016 To create a macOS Sierra USB installer, you’ll need a USB 2.0 or USB 3.0 drive with a capacity of at least 8GB. The process of creating the USB installer deletes all data on the USB drive, so make sure it doesn’t contain any important files. Select Install macOS (or Install OS X) from the Utilities window, then click Continue and follow the onscreen instructions. Learn more For more information about the createinstallmedia command and the arguments that you can use with it, make sure that the macOS installer is in your Applications folder, then enter this path in Terminal. I used this thumb drive to create a macOS Big Sur installer. You can use a thumb drive, external hard drive or SSD. The 32GB drive I used has both USB-C and USB-A (USB 2 speed, however, so it’s.

For system admins and Mac app developers, they usually need to install different versions of macOS on different Macs. Hence, they have to prepare for multiple USB drives (one macOS installer sits on one USB drive). This is really inconvenient! You have to keep and carry multiple USB drives at the same time.

Creating a multiple macOS bootable installer on a single USB allows you to install different macOS versions on different computers. You can even run them as VMs in Windows, which makes this a very versatile process. But what about the tools to get the job done. Can this be done on a Mac? Absolutely! That's what we're about to show you.

Advantages of Multiboot USB Installer for macOS

Having a USB installer for multiple versions of macOS can help you in many ways:

  • You can choose a macOS version when clean-installing on an older Mac.
  • You can switch versions on the same computer by re-installing a different version of macOS.
  • You can have multiple macOS versions on VM in Windows using Parallels or a similar application.
  • Quickly repair any version of macOS if you have multiple versions ready to use.
  • Easy to carry around wherever you go.

The real advantage here is flexibility. You can use these macOS versions on any Mac or PC by spending just a few minutes for the installation process. Even running Mac on Windows is as simple as deploying VMs and putting multiple macOS versions on them. In short, if you want to run any macOS version on any computer, the multiboot macOS installer is a blessing in that sort of situation.


Before actually creating the multiboot USB installer, you'll need to take care of a few preparatory tasks:

● Get a USB drive (USB 3.0, fast reading and writing speed) with at least 10 GB free space for each macOS version. The general practice is to always have a buffer of a few GB since OS sizes vary depending on the source. For instance, third-party sources may have added some bloatware that increases the size of the file.

● Download macOS Installation app or DMG files for the versions of macOS you intend to put on this drive. As mentioned above, you may have some bloatware in the installer packages. To avoid this, try to get it from Mac App Store or a reliable third-party repository.

● A working Mac computers with enough free space. You need to download macOS install app on Mac, Each macOS installation app takes a plenty of free storage. However, you can download dmg file from other websites and put them on external USB drive to avoid taking free storage on your Mac.

● Ensure that the USB is partitioned properly. If not, you'll need to do that before creating the installer. We'll show you how to do that. It's merely a question of checking whether partitioning is enabled and then setting it up for each of the macOS versions you want on the USB drive.

● Know how to use Disk Utility and Terminal on your Mac. Both of which are available by default. Make sure you're familiar with using these applications because they can impact your Mac at the system level.

How to Create a Multiboot macOS USB Installer on a Mac

If you're ready, let's get started.

Step 1: Partition USB Drive on Mac

The first step is to create new partitions on external USB drive. It depends on how many macOS versions to be kept on that USB drive. In the following example, we will create 3 partitions for macOS Big Sur, Catalina and Mojave, which are the most popular macOS release up to now.

Insert USB drive on Mac and open Disk Utility app from Spotlight. Right click the USB drive name at left sidebar and you will see Partition tab is visiable. Click on it to create a new partition.

From the new settings page, please give a name to new partitoon and choose Mac OS Extended Journaled)in Format tab. Finally, set a size for new partition. For macOS Big Sur, please make it to at least 20GB. 15GB For other macOS versions.

Warning: APFS formatted disk can not be used as a bootable install media.

Back to Disk Utility, you can now click the Partition button. Clik the space in Untitled partition and the + button to add another partition. If you don't see the + symbol, change the Format field to Mac OS Extended Journaled). You can now adjust the space available for each macOS installation file.

To add multiple partitions, repeat step 2 and hit Apply after creating each partition. For this example, we'll create three new partition for a total of four available partitions: one for macOS Big Sur, one for macOS Catalina and one for macOS Mojave.

Step 2: Get Unqiue Volume Name for Each Partition

Make Mac Os Usb Installer

After completing the above step, the USB drive is divided into four different partitions. You have to get the unique identifier so you can write different macOS versions to a specific partition. Open Terminal app and run ls /Volumes command to display mounted volume name for each partition of that USB drive.

In the following example, the volume names are Big Sur, Catalina and Mojave. We will use this information in next step.

Step 3: Create macOS Bootable USB Installer

Back to Terminal window, run the following command to create macOS Big Sur USB installer. Make sure you already download macOS Big Sur Installer app from Mac App Store.

sudo /Applications/Install macOS Big --volume /Volumes/Big Sur

Enter login password if prompted and confirm with a 'y' if asked to. Wait about 3-6 minutes and you will see a message, indicating install media is available for usage.

If you're only creating a single macOS installer, you can eject the drive at this point. However, since we're adding another macOS version to the USB, repeat the same steps to put macOS Catalina installer on the USB with this modified command.

sudo /Applications/Install macOS --volume /Volumes/Catalina

Once it is completed, repeat the process and start to create macOS Mojave USB installer with this similar command:

Make Macos Usb Installer

sudo /Applications/Install macOS --volume /Volumes/Mojave

Now a multiboot installer for macOS Big Sur, Catalina and Mojave is created successfullyon your Mac!

Step 4: Boot Mac from Multiboot USB Installer

Insert the multiboot USB installer into a target Mac. Power on the machine and keep pressing Option key to bring up Startup Boot Manager, where you can select a macOS instance to be installed on this Mac.


The most challenging part in this tutorial is to properly partition the USB drive. Also, you should download macOS installer app or dmg file before moving ahead. This will take a lot of time. And the rest part is quite simple and error free.

Computers fail. It’s a fact of life, whether you like it or not. Eventually a file is going to get corrupted, a patch is going to screw something up, or you’re going to accidentally delete a critical component. It happens to all operating systems all the time, MacOS included. Yes Mac fanboys, your computer too.

The solution to this problem is simple. You should be keeping constant backups using Time Machine (or even better, relying on offsite backups as well). But this only solves part of the problem. If you are forced to wipe your entire Mac hard-drive, what’s the easiest way to get a hold of a fresh copy of MacOS and do a clean install?

The answer is to make a bootable installer on a USB stick, and it really isn’t difficult in the slightest, as I will now show you. Then you can have it sitting by the computer standing by, just in case.

Bootable MacOS Installer Recipe



1 USB stick, with minimum 8GB space (blank)
MacOS Installation File (Currently Sierra)
Disk Creator
Time & patience

Step 1 – Get a Blank USB Stick

Make sure you have a blank USB stick, and that it has a minimum of 8GB space. For the purposes of speed, you should also get a proper USB 3.0 stick, and not use some crappy little 2.0 stick that will crawl along at a snail’s pace.

Also, transfer any existing critical files off the stick, because when Sierra jumps on there, everything else is going to get nuked. It’s a bit anti-social like that.

Step 2 – Get The MacOS Operating System

Download the MacOS installation file. This should open up your Mac App Store, but if not, click on “View In Mac App Store” to give the Mac store a nudge.

Now click “Download” to start the Sierra installation. I was redirected to the German page since that’s where I am, but you will be redirected to the page of your own country.

At this point, you need to be aware of two things.

First, your Mac will get itself a bit worked up, because you are already running Sierra (hopefully). You will therefore get a box where you have to confirm you want the file. It is basically asking you “what the hell do you need the Sierra installation file for again?”. To confirm you still want the file, click “continue” and the download will start.

Second, it took me 45 minutes to get the whole file, and I am on a fast Internet connection. The size of the installation file is 5GB in total. So it’s probably best to start this, and then go off and do something else.


When the file has finished downloading, you will find it in your Applications folder under the name “Install MacOS“.

Make macos usb installer

I should also point out that as soon as the installation file has finished downloading, it will immediately open up and attempt to start the installation process on your computer. Simply close the window. But it is a bit persistent and may try again.

Step 3 – Insert Your USB Stick Into The Computer

Pretty self-explanatory!

Step 4 – Download & Install Disk Creator

The next step is to download and install Disk Creator. Then open it up and you will see this :

Create macos sierra usb installer

Choose the USB stick (using the drop-down menu at the top), then click “Choose a MacOS Installer“. Navigate to where the OS installation file is, and choose it. The icon of the file will then appear in the window at the top.

It will ask you if you are sure you want to proceed with the wiping of the USB stick and the installation of the installer. Then you have to enter your MacOS password for the process to begin. Now sit back and wait. It will take some time.

One Drawback Of Creating a USB Installer

There are many advantages of a USB installer, including the ease of installing a fresh new system onto a Mac without any jiggery-pokery with the Terminal. But one drawback is that Apple brings out so many regular OS updates that your installer is soon going to be out-of-date, if you don’t need to use it for quite some time.

Make Macos Installer Usb On Windows

Of course this is easily solved by installing the OS version you have, then going to the Mac store and installing all of the updates. But that could be quite a few, depending on how old your USB installer is.

Using The Installer

To begin the installation process using the USB stick, put it into the Mac’s USB port. Then simply boot up your Mac, and as it is starting up, hold down the Option key. This will activate it, and just follow the on-screen instructions from Apple.

See how easy it was? But if you do have a problem, let me know in the comments. I will do what I can to assist.