Install Windows from a Flash Drive

This topic covers how to manually create a Windows installation flash drive from Windows installation ISO disc image file or DVD, and is intended for manufacturers looking into creating media that they can use to manufacture Windows devices.


The steps described on this page assume you have Windows installation media and access to a Windows technician PC. If you're looking for an easy, automated way to create a bootable Windows installation flash drive, see:

What you need

  • Windows installation media. This could be an installation .ISO or DVD
  • Flash drive (USB or MiniSD depending on what your device supports) with at least 5GB free space. This drive will be formatted, so make sure it doesn't have any important files on it.
  • Technician PC - Windows PC that you'll use to format the flash drive
  • Target device - A device that you'll install Windows on

Step 1 - Format the drive and set the primary partition as active

  1. Connect the flash drive to your technician PC.

  2. Open Disk Management: Right-click on Start and choose Disk Management.

  3. Format the partition: Right-click the USB drive partition and choose Format. Select the FAT32 file system to be able to boot either BIOS-based or UEFI-based PCs.


    FAT32 has a file size limit of 4GB If your WIM image is larger than 4 GB, see If your Windows image is larger than 4GB below.

  4. Set the partition as active: Right-click the USB drive partition and click Mark Partition as Active.


    If Mark Partition as Active isn't available, you can instead use diskpart to select the partition and mark it active.

Step 2 - Copy Windows Setup to the flash drive

  1. Use File Explorer to copy and paste the entire contents of the Windows product DVD or ISO to the flash drive.

  2. Optional: add an unattend file to automate the installation process. For more information, see Automate Windows Setup.

Step 3 - Install Windows to the new device

  1. Connect the flash drive to a new device.

  2. Turn on the device and press the key that opens the boot-device selection menu for the computer, such as the Esc/F10/F12 keys. Select the option that boots the device from the flash drive.

    Windows Setup starts. Follow the instructions to install Windows.


    You may need to consult the device manufacturer instructions to configure it for booting from the flash drive if this process does not work on your device.

  3. Remove the flash drive.

If your Windows image is larger than 4GB

Windows install drives are formatted as FAT32, which has a 4GB filesize limit. If your image is larger than the filesize limit:

  1. Copy everything except the Windows image file (sources\install.wim) to the flash drive (either drag and drop, or use this command, where D: is the mounted ISO and E: is the flash drive.)

    robocopy D: E: /s /max:3800000000
  2. Split the Windows image file into smaller files, and put the smaller files onto the flash drive:

    Dism /Split-Image /ImageFile:D:\sources\install.wim /SWMFile:E:\sources\install.swm /FileSize:3800


    Windows Setup automatically installs from this file, so long as you name it install.swm.

Windows Setup Technical Reference