Install Windows from a USB Flash Drive

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

Tip

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 USB Windows installation drive, see:

What you need

  • Windows installation media. This could be an installation .ISO or DVD
  • USB flash drive 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 USB flash drive
  • Destination PC - A PC that you'll install Windows on

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

  1. Connect the USB 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.

    Note

    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.

    Note

    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 USB flash drive

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

  1. Connect the USB flash drive to a new PC.

  2. Turn on the PC 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 PC from the USB flash drive.

    Windows Setup starts. Follow the instructions to install Windows.

  3. Remove the USB flash drive.

If your Windows image is larger than 4GB

Windows USB 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 USB drive (either drag and drop, or use this command, where D: is the mounted ISO and E: is the USB flash drive.)

    robocopy D: E: /s /max:3800000000

  2. Split the Windows image file into smaller files, and put the smaller files onto the USB drive:

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

    Note

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

Windows Setup Technical Reference