How to Make a Windows 11 Bootable USB on a Mac

To make a Windows 11 bootable USB on a Mac, download the official Windows 11 ISO from Microsoft, format an 8 GB or larger USB drive as FAT32 with a GPT scheme in Terminal, copy the ISO contents across with rsync, then split the oversized install.wim file with wimlib so it fits under FAT32's 4 GB limit. Rufus does not run on macOS.

Before You Start: What You Need

Preparing a Windows installer on macOS is slightly awkward because Microsoft's own Media Creation Tool and the popular Rufus utility only run on Windows. Apple's Boot Camp Assistant, which once built Windows USB drives, is not available on Apple silicon Macs and is not the right tool here either. The method below uses only built-in macOS tools plus one free command-line package.

• A USB flash drive of 8 GB or more. The Windows 11 ISO is roughly 6 to 7 GB, depending on language and release, so a 16 GB drive gives you more headroom. A USB 3.0 drive will be far quicker than an old USB 2.0 stick.
• A Mac running a recent version of macOS with an administrator account.
• Homebrew (the macOS package manager) to install wimlib. If you do not have it, install it from brew.sh first.
• The target PC's details. Windows 11 needs a 64-bit processor, 4 GB of RAM, 64 GB of storage, UEFI firmware with Secure Boot capability and TPM 2.0. If you are unsure whether the PC qualifies, see our guide to checking your computer specs before you build the drive.

Step 1: Download the Official Windows 11 ISO

1. On your Mac, open Microsoft's official "Download Windows 11" page.
2. Scroll to the section titled Download Windows 11 Disk Image (ISO) for x64 devices.
3. Choose Windows 11 (multi-edition ISO for x64 devices), confirm, then select your language and click Download.
4. Wait for the file to finish. It usually lands in your Downloads folder and has a name like Win11_English_x64.iso.

Pick the x64 ISO even though you are on a Mac. The USB drive is meant for an ordinary Intel or AMD PC. Microsoft also publishes an Arm64 ISO, but that one is for Arm devices and virtual machines on Apple silicon, not for typical desktops and laptops.

Optional but sensible: verify the download. Microsoft lists a SHA-256 hash beside the download link. In Terminal, run the following and compare the output to Microsoft's value:

shasum -a 256 ~/Downloads/Win11_English_x64.iso

If the strings differ, the download is corrupted or incomplete and you should download it again. Avoid ISOs from third-party sites, since a modified installer is a real security risk.

Step 2: Find Your USB Drive in Terminal

1. Plug in the USB drive.
2. Open Terminal (Applications, then Utilities, then Terminal).
3. Run:

   diskutil list external

4. Look for your flash drive by its size and name. It will appear as something like /dev/disk4 (external, physical). Note the identifier, for example disk4.

Be careful here. Every command that follows will wipe whatever disk identifier you give it. If you have an external backup drive plugged in, unplug it for now so there is no chance of choosing the wrong one. Match the capacity shown in diskutil to the capacity printed on your USB stick.

Step 3: Format the USB Drive as FAT32 with GPT

Run the command below, replacing disk4 with your own identifier. This names the new volume WIN11, formats it as FAT32 (shown as MS-DOS in macOS) and uses a GUID Partition Table:

diskutil eraseDisk MS-DOS "WIN11" GPT /dev/disk4

When it finishes, a drive named WIN11 should appear on your desktop or in Finder. FAT32 matters because almost all UEFI firmware can boot from it without extra steps. NTFS and exFAT are not read by many motherboards at boot time unless a special loader is used.

If macOS says it cannot unmount the disk, close any Finder windows showing the drive and run diskutil unmountDisk /dev/disk4 before trying again. If Terminal reports an operation not permitted error, open System Settings, go to Privacy and Security, and grant Terminal "Full Disk Access" or "Removable Volumes" access, then restart Terminal.

Step 4: Mount the ISO and Copy Everything Except install.wim

Mount the ISO image so macOS treats it like a disc:

hdiutil mount ~/Downloads/Win11_English_x64.iso

The output tells you the mount point, which looks like /Volumes/CCCOMA_X64FRE_EN-US_DV9. The exact name varies with the ISO release and language, so use the name that appears on your screen, not the one printed here.

Now copy every file except the large install.wim:

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

Notes on this command:

• The trailing slash after the source folder is important. It copies the contents rather than the folder itself.
• The copy can take a while, particularly on slower flash drives. Do not unplug the drive while it runs.
• The version of rsync bundled with macOS is old, but it supports these options without trouble.

The file you excluded, sources/install.wim, is the actual Windows image. In current Windows 11 ISOs it is often larger than 4 GB, which FAT32 cannot store. We handle that in the next step.

Step 5: Split install.wim and Copy It to the USB Drive

1. Install wimlib with Homebrew:

   brew install wimlib

2. Split the image into pieces smaller than 4 GB and write them straight to the USB drive:

   wimlib-imagex split /Volumes/CCCOMA_X64FRE_EN-US_DV9/sources/install.wim /Volumes/WIN11/sources/install.swm 3800

3. Wait for the progress indicator to reach 100 percent. The number 3800 is the maximum size of each part in megabytes.

You should now see install.swm, install2.swm and possibly more files inside the sources folder on the USB drive. Windows Setup recognises split .swm files automatically, so nothing else needs to change. If your ISO contains an install.esd file instead of install.wim, check its size. If it is under 4 GB, simply copy it normally. If it is larger, you would need a different conversion route, which is rare with official ISOs.

Step 6: Eject the Drive Safely

1. Eject the ISO: hdiutil unmount /Volumes/CCCOMA_X64FRE_EN-US_DV9 (use your own volume name).
2. Eject the USB drive from Finder, or run diskutil eject /dev/disk4.

Your bootable Windows 11 installer is ready. Quick check before you leave your Mac: the WIN11 volume should contain folders named boot, efi, sources and support, plus bootmgr, bootmgr.efi and setup.exe.

Step 7: Boot the PC From the USB Drive

1. Plug the USB drive into the target PC and power it on.
2. Press the boot menu key immediately and repeatedly. This differs by manufacturer. Common keys are F12 (Dell, Lenovo), F9 or Esc (HP), F8 or F11 (various), Esc or F8 (ASUS) and F11 (MSI). Check the splash screen or the manual for yours.
3. Select the entry that shows your USB drive and the word UEFI.
4. When the Windows Setup screen loads, choose your language and follow the prompts.

Selecting the UEFI entry is not a minor detail. If you boot the same USB in legacy mode, Windows will later complain about the disk partition style. Our guide to the "Windows cannot be installed to this disk" error explains that mismatch in full.

Troubleshooting a Mac-Made Installer

The USB drive does not appear in the boot menu

Confirm the PC is set to UEFI boot, not legacy-only. Try a different USB port, ideally a rear port on a desktop. Reformat the drive and repeat the copy if you suspect an interrupted rsync. Some older machines do not boot USB drives larger than 32 GB reliably, so a smaller stick can help.

"A media driver your computer needs is missing"

This often points to a damaged copy or a USB 3.0 port issue. Re-verify the ISO hash, repeat the copy and try a USB 2.0 port.

Setup says the PC does not meet requirements

Windows 11 checks for TPM 2.0, Secure Boot capability, a compatible CPU and at least 4 GB of RAM. Look in the BIOS for settings called TPM, fTPM, PTT or Secure Boot and enable them. Microsoft does not support running Windows 11 on hardware that fails these checks, and workarounds can leave a system that does not receive updates reliably, so we recommend checking compatibility first.

The copy fails with "File too large"

You probably tried to copy install.wim directly to FAT32. Delete the partial file and use the split command in Step 5.

Other Ways to Create the Installer

• Use a Windows PC. If a friend or colleague has a Windows computer, Microsoft's Media Creation Tool or Rufus can build the drive in a few clicks. In Rufus you would select the ISO, choose the GPT partition scheme and UEFI target system, then click Start.
• Use a Windows virtual machine on your Mac. Virtualisation software such as Parallels, VMware Fusion or UTM can run Windows, and some allow passing a USB drive through so Rufus can write to it. Results vary with USB passthrough support, so treat this as a fallback.
• Use a third-party Mac utility. Some paid and free apps automate the same split-and-copy process. They work, but the Terminal method above uses only well-known tools and gives you full visibility of what is happening.

When to Call a Professional

Creating the installer is the easy part. Problems tend to appear during installation, such as a PC that will not recognise its drive, repeated boot loops, failed upgrades that threaten your files, or a machine that is not eligible for Windows 11. If you are weighing a reinstall on a computer with important data, getting advice first can save a lot of trouble. We can guide you through the process or handle it for you over a secure remote session. See our Windows support service, or, depending on where you are, our remote computer repair in Canada and remote computer repair in the USA pages.

Frequently Asked Questions

Can I use Rufus on a Mac?

No. Rufus is a Windows-only program and there is no official macOS version. Mac users either use Terminal as shown above, borrow a Windows PC, or run Rufus inside a Windows virtual machine with USB passthrough.

Why does the USB need to be FAT32 instead of NTFS or exFAT?

Most PC firmware can boot from FAT32 on a UEFI system without extra software. NTFS and exFAT are not natively readable by the boot firmware on many motherboards, so a drive formatted that way may not appear as a bootable option unless a special loader is added.

How big does the USB drive need to be?

Microsoft states a minimum of 8 GB. The ISO is large, so a 16 GB drive gives comfortable space for the files plus the split image.

Will this USB drive boot a Mac?

No. It is designed for PCs with Intel or AMD processors and UEFI firmware. Apple silicon Macs cannot boot a standard x64 Windows installer. To run Windows on those Macs you would use virtualisation software with Microsoft's Arm version of Windows.

Do I need a product key to install Windows 11?

You can start the installation without entering one, but Windows needs a valid licence to activate fully. A PC that previously had a genuine copy of Windows 10 or 11 often reactivates automatically once connected to the internet after installation.