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Created October 2, 2025 05:12
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  1. @acarril acarril created this gist Nov 18, 2022.
    72 changes: 72 additions & 0 deletions bootable-win-on-mac.md
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    For some reason, it is surprisingly hard to create a bootable Windows USB using macOS. These are my steps for doing so, which have worked for me in macOS Monterey (12.6.1) for Windows 10 and 11. After following these steps, you should have a bootable Windows USB drive.

    ### 1. Download a Windows disc image (i.e. ISO file)

    You can download [Windows 10](https://www.microsoft.com/en-us/software-download/windows10ISO) or [Windows 11](https://www.microsoft.com/en-us/software-download/windows11) directly from Microsoft.

    ### 2. Identify your USB drive

    After plugging the drive to your machine, identify the name of the USB device using `diskutil list`, which should return an output like the one below. In my case, the correct disk name is `disk2`.

    ```text
    /dev/disk0 (internal, physical):
    #: TYPE NAME SIZE IDENTIFIER
    0: GUID_partition_scheme *500.3 GB disk0
    1: EFI EFI 314.6 MB disk0s1
    2: Apple_APFS Container disk1 500.0 GB disk0s2
    /dev/disk1 (synthesized):
    #: TYPE NAME SIZE IDENTIFIER
    0: APFS Container Scheme - +500.0 GB disk1
    Physical Store disk0s2
    1: APFS Volume MacHDD - Data 180.3 GB disk1s1
    2: APFS Volume MacHDD 15.4 GB disk1s2
    3: APFS Snapshot com.apple.os.update-... 15.4 GB disk1s2s1
    4: APFS Volume Preboot 481.8 MB disk1s3
    5: APFS Volume Recovery 1.1 GB disk1s4
    6: APFS Volume VM 1.1 GB disk1s5
    /dev/disk2 (external, physical):
    #: TYPE NAME SIZE IDENTIFIER
    0: FDisk_partition_scheme *15.5 GB disk2
    1: DOS_FAT_32 WINDOWS10 15.5 GB disk2s1
    ```

    ### 3. Format USB drive

    Format the drive with the following command, substituting `disk2` with whatever is the one that corresponds in your machine.
    ```zsh
    diskutil eraseDisk MS-DOS "WINDOWS10" MBR disk2
    ```

    ### 4. Mount the Windows ISO and check its size

    Mount the ISO file in your system (usually by simply double-clicking it), and verify it's listed in `/Volumes`—the disk name usually starts with `CCCOMA_`. With the disk mounted, check the size of the `sources/install.wim` file with the following command:
    ```zsh
    ls -lh /Volumes/CCCOMA_X64FRE_EN-US_DV9/sources/install.wim
    ```

    ### 5. Copy (almost) all files to USB drive

    **If `sources/install.wim` is less than 4GB in size**, you can copy all the files from the mounted disk image onto the USB drive with the following command (notice the trailing slash in the first path!):
    ```zsh
    rsync -avh --progress /Volumes/CCCOMA_X64FRE_EN-US_DV9/ /Volumes/WINDOWS10
    ```

    **If `sources/install.wim` is more than 4GB**, then we'll need to split the file before copying it. In the meantime, we can copy all the other files from the mounted image onto the USB drive with the following command (again, notice the trailing slash in the first path!):
    ```zsh
    rsync -avh --progress --exclude=sources/install.wim /Volumes/CCCOMA_X64FRE_EN-US_DV9/ /Volumes/WINDOWS10
    ```

    ### 6. Use `wimlib` to split and copy `sources/install.wim`

    If `sources/install.wim` is more than 4GB, it is too large to copy onto a FAT32-formatted drive. Microsoft's [official solution](https://learn.microsoft.com/en-us/windows-hardware/manufacture/desktop/install-windows-from-a-usb-flash-drive?view=windows-11) is to split the file, and there is a free utility available in macOS and Linux to do so—`wimlib`. The tool can be installed with [Homebrew](https://brew.sh/):
    ```zsh
    brew install wimlib
    ```

    After installing `wimlib`, split and copy `sources/install.wim` using the following command:
    ```zsh
    wimlib-imagex split /Volumes/CCCOMA_X64FRE_EN-US_DV9/sources/install.wim /Volumes/WINDOWS10/sources/install.swm 3800
    ```
    Here, `3800` means that the file should be split in 3,800MB chunks.