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

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

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

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

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

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

Install Windows

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

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

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.

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

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

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