How to make a Windows 11 Bootable USB on a Mac

Macs are great, except for making a Windows install USB. For whatever reason, Windows USB’s use FAT32, meaning the maximum file size is 4GB. This is fine, except that one Windows file (install.wim) exceeds the limit. However, there is a workaround that works, and this is dedicated to detailing this process. This may seem like a lot of work, but is actually really easy to do!

Step 0: Requirements

For this guide, you will need:

• 8GB or larger USB (Will be erased, so make sure it is backed up)
• Windows 11 ISO (Download guide is on my page)
• MacOS

Once you have all of those, go to step 1.

Step 1: Installing Homebrew and Wimlib

In order to add the install.wim file, we will need a program called wimlib, which is terminal based. To install wimlib, we use Homebrew, a free (and open source) package manager. To install this, open Terminal and paste this command.

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

When you hit enter, you should see something like this.

Homebrew asking for SUDO access.

Enter your password (Terminal blanks this out for security reasons). You should see something like this.

What Homebrew asks to do.

This explains what Homebrew will do. What it does is create folders used to store its files and then installs itself. Press enter and wait for a few minutes. When done, it should appear like this in your window. If you don’t see “Installation successful!”, then it is not successful.

The output when Homebrew is done installing.

Once done, enter this command.

brew install wimlib

What this will do is install wimlib (and what wimlib needs), which is used to split the large Install file into two parts. Once done, you should see this.

Output when Wimlib is installed.

Now, you are ready to actually make the USB. Open Disk Utility. You should see a window like this.

Press ⌘+2 with that window focused. This will show all devices and should change the Disk Utility window to look something like this.

Once here, select your USB drive (it should be in the External tab. Mine is called “USB DISK 3.0 Media”). Make sure you choose the one to the very left (it should be un-indented and have an arrow next to it). For this next step, you will need to know your computer’s firmware type. This is important since UEFI drives will not work on Legacy, but Legacy is not good to use for UEFI. A good general rule of thumb is that most computers made after 2007 will use UEFI. Press erase, and you should see a window like this.

Name your drive “WIN11”, and choose the Scheme as “GUID Partition Map” for UEFI and “Master Boot Record” for Legacy. Choose “MS-DOS (FAT)” as the format. Below are examples of Legacy and UEFI formatting.

An example of the erase selection for UEFI (most common).

An example of the erase selection for Legacy (less common).

Once you are done, press “Erase” and wait for your drive to erase. Wait for this to complete, then press “Done” and switch back to your Terminal. Type the following command and then drag the Windows 11 ISO into your Terminal.

hdiutil mount

Your Terminal should look something like this, but with a different path.

rsync -vha --exclude=sources/install.wim /Volumes/CCCOMA_X64FRE_EN-US_DV9/* /Volumes/WIN11

Press enter to mount the ISO. Then, enter the above command, but do not press enter yet.

Add “/*” after the ISO volume to look like this.

This will copy the files from the ISO (excluding the large install.wim) to your USB drive. Press enter when your window looks somewhat like this.

You will see a lot of text. What this is doing is copying every file except install.wim, and then showing you the files as they are being copied. This will take a while depending on your drive speed and your Mac’s speed. Once this process is complete, the Terminal should look like this.

Once this is done, you are almost there. The last step is to add the install.wim. This is what we downloaded wimlib for previously. Enter the following command, then press enter. Note that the “3500” means how big the biggest file should be. Feel free to change this (but keep it less than 4000).

wimlib-imagex split /Volumes/CCCOMA_X64FRE_EN-US_DV9/sources/install.wim /Volumes/WIN11/sources/install.swm 3500

Your window should look something like this. This is the command to split the drive into two parts. This will take a while depending on the speed of your CPU. Once it is done, your Terminal should look like this.

Once you see this, you are done! You can now unplug your USB drive (after ejecting, of course) and use this to install Windows 11! If this tutorial was helpful, please follow as it means a lot. Good luck!