How to Install Windows From an External Hard Drive

by Ruri Ranbe

    Since the release of Windows XP, installing operating systems from a CD or DVD (as opposed to a floppy diskette) has been common practice. Some computers, like netbooks, however, don't have a disc drive, which prevents users from upgrading or reinstalling the OS. With the release of Windows 7, Microsoft enabled users to download the Windows 7 DVD as an ISO archive file from the Microsoft Store. If your DVD drive isn't working, or if your computer lacks a disc drive altogether, you can copy the archive file to an external hard drive and install Windows 7 via a USB port.

    Prepare the Drive

    Step 1

    Download the Windows 7 USB/DVD Download Tool (link in Resources).

    Step 2

    Launch the EXE file when the download completes. Follow the directions in the wizard to install the tool.

    Step 3

    Open the Windows 7 USB/DVD Download Tool from the Windows Start menu. Click "Browse" and select your Windows 7 ISO.

    Step 4

    Click "Next." Connect the USB drive to the computer and then click "USB Device."

    Step 5

    Choose the removable drive from the drop-down menu. Click "Begin Copying" to create a bootable device.

    Install Windows

    Step 1

    Restart the computer. Follow the directions on the boot screen to access setup. A message such as "Press to Enter BIOS Setup" will appear.

    Step 2

    Use the arrow keys to choose the "Boot," "Advanced," "Advanced BIOS Features" or similar option from the menu. Press "Enter."

    Step 3

    Select "First Boot Device," press "Enter" and select "USB" from the list, or use the arrow pad to highlight "USB" and press "+" to move the device to the top of the list.

    Step 4

    Press "F10" to exit setup. The computer will boot to the external drive. Choose your language and keyboard options. Click "Next."

    Step 5

    Click "Install Now." Review the license agreement and click "Next." Click "Custom."

    Step 6

    Choose your computer's hard disk from the list of devices. Click "Next" to install Windows 7 to the PC from the external drive.


    • System setup varies from PC to PC. Check your computer's documentation for more assistance if you have any difficulty navigating setup.
    • Transfer the files on the USB flash drive to another storage device before using the Windows 7 USB/DVD Download Tool.


    • Installing Windows 7 to the hard drive will erase all of the data contained on the drive.

    About the Author

    Ruri Ranbe has been working as a writer since 2008. She received an A.A. in English literature from Valencia College and is completing a B.S. in computer science at the University of Central Florida. Ranbe also has more than six years of professional information-technology experience, specializing in computer architecture, operating systems, networking, server administration, virtualization and Web design.

    Photo Credits

    • Jeffrey Hamilton/Digital Vision/Getty Images