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Muhammad Usman
Muhammad Usman

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Creating a Windows 11 Bootable USB on an Apple Silicon (M1) Mac

#bootableusb #apple #mac #windows

I recently needed to create a Windows 11 bootable USB on a MacBook with an M1 chip and use it to install Windows 11 on a Windows laptop.

The process is slightly different from creating a Windows USB from a Windows PC because Microsoft's Media Creation Tool is a Windows .exe application and doesn't run natively on macOS.

Here's the complete process that worked for me.

What I Used

  • MacBook with Apple Silicon M1
  • 64GB USB drive
  • Windows 11 x64 ISO
  • Windows laptop
  • Homebrew
  • wimlib

⚠️ The USB drive will be completely erased during this process. Make sure you don't have important data on it.

1. Download Windows 11 ISO

Download the Windows 11 x64 ISO from Microsoft's official website.

Make sure you download the x64 ISO, not the ARM64 version, because the target Windows laptop uses the standard Intel/AMD architecture.

In my case, the ISO was located at:

/Users/productbox/Downloads/Win11_25H2_English_x64_v2.iso
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2. Identify the USB Drive

Connect the USB to the Mac and run:

diskutil list
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My USB appeared as:

/dev/disk4 (external, physical):
   #:                       TYPE NAME                    SIZE
   0:     FDisk_partition_scheme                        *62.9 GB
   1:             Windows_FAT_32 RIZWAN                  62.9 GB
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The important part here was:

/dev/disk4
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⚠️ Always verify the disk number on your own Mac.

Never blindly use /dev/disk4, because the disk number can be different on another machine.

3. Format the USB

I formatted the USB as FAT32 with a GPT partition scheme:

diskutil eraseDisk MS-DOS WIN11 GPT /dev/disk4
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After this, the USB was mounted as:

/Volumes/WIN11
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4. Install wimlib

Because Windows 11's install.wim can be larger than FAT32's 4GB single-file limit, I used wimlib.

If Homebrew is already installed:

brew install wimlib
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5. Mount the Windows ISO

I mounted the ISO using:

hdiutil attach "/Users/productbox/Downloads/Win11_25H2_English_x64_v2.iso"
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macOS mounted it at:

/Volumes/CCCOMA_X64FRE_EN-US_DV9
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6. Copy Windows Files to the USB

I copied the Windows installation files:

cp -R "/Volumes/CCCOMA_X64FRE_EN-US_DV9/"* /Volumes/WIN11/
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However, this produced:

cp: /Volumes/WIN11/sources/install.wim: fcopyfile failed: File too large
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This is expected when using FAT32.

Why?

FAT32 has a maximum single-file size of approximately 4GB.

The Windows 11 install.wim in my ISO was around 7GB, so it couldn't fit as one file.

7. Split install.wim

This is where wimlib comes in.

I ran:

wimlib-imagex split \
"/Volumes/CCCOMA_X64FRE_EN-US_DV9/sources/install.wim" \
"/Volumes/WIN11/sources/install.swm" \
3800
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The command completed successfully:

Splitting WIM: 7177 MiB of 7177 MiB (100%) written, part 3 of 3
Finished splitting "/Volumes/CCCOMA_X64FRE_EN-US_DV9/sources/install.wim"
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It created three files:

install.swm
install2.swm
install3.swm
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In my case:

install.swm    3.2G
install2.swm   3.7G
install3.swm    79M
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Windows Setup can use these split WIM files as the installation image.

8. Remove the Failed install.wim

Because the original copy had failed, I removed the incomplete install.wim from the USB:

rm -f "/Volumes/WIN11/sources/install.wim"
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Then verified the split files:

ls -lh /Volumes/WIN11/sources/install*.swm
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The three .swm files were present.

9. Eject the USB

Once everything was ready:

diskutil eject /dev/disk4
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After macOS confirmed the disk was ejected, I removed the USB.

10. Boot the Windows from USB

I inserted the USB into the Windows laptop and entered the UEFI/BIOS boot menu.

The USB appeared as:

EFI USB Device
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I selected it and pressed Enter.

Initially, I encountered a Windows Recovery screen with:

File: \Windows\system32\winload.efi
Error code: 0xc0000225
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This turned out not to be the Windows installer loading correctly. After returning to the firmware/boot menu and selecting the USB boot entry correctly, the Windows installation started successfully.

🎉 Windows 11 Setup launched and the installation process began.

Conclusion

Creating a Windows 11 bootable USB on an M1 Mac is absolutely possible without having another Windows PC.

The key issue is the install.wim file being larger than FAT32's 4GB file limit.

The important part of the process is:

Windows 11 x64 ISO
        ↓
Format USB as FAT32/GPT
        ↓
Copy Windows files
        ↓
Split install.wim with wimlib
        ↓
Remove incomplete install.wim
        ↓
Boot Windows from EFI USB
        ↓
Windows 11 Setup
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If you're also using an Apple Silicon Mac and need to create a Windows 11 installation USB for another Intel/AMD laptop, this approach can save you from needing a separate Windows PC just to create the installer.

Tip: Always double-check your USB's disk identifier with diskutil list before running any eraseDisk command. Accidentally selecting your Mac's internal disk can result in data loss.

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