How to Make a Bootable Flash Drive

by Jeff Grundy
Before you can boot your computer from a flash drive, you must ensure the option is active in the system BIOS.

Before you can boot your computer from a flash drive, you must ensure the option is active in the system BIOS.

When you turn on your computer and log in to Windows, the PC boots from the primary hard disk drive -- the "C:" drive -- in the machine. Usually you won't need to boot from another drive or device. However, if you need to run diagnostics on a faulty Windows installation or need to reinstall the operating system, you may need to boot from a different drive. Virtually all modern computers allow you to boot from drives such as a floppy, CD or DVD drive, and many also enable booting from a USB flash drive. A bootable USB flash drive allows you to run diagnostic software on your PC in the event of an emergency or provides you with a means of reinstalling Windows if you do not have an optical drive in the computer.

Back Up the Flash Drive

Insert the flash drive into an empty USB port on the computer and wait a few seconds for Windows to detect and initialize it as a removable storage device automatically.

Click the "Open Folder to View Files" option in the AutoPlay window that pops up to open Windows Explorer and display the files and folders stored on the USB flash drive.

Press the "Ctrl-A" keys to highlight and select all of the files and folders on the flash drive. Press "Ctrl-C" to copy the data to the Windows clipboard.

Browse to a folder on your hard drive in the Windows Explorer window where you want to save the files and folders from the USB flash drive. Double-click the desired folder to open it. Alternatively, click the "New Folder" button and create a new folder in which to save the files and folders.

Press the "Ctrl-V" keys to copy the files from the Windows Clipboard into the destination folder for the saved files.

Format Flash Drive and Make Bootable

Click the Start button, then type "cmd" in the search box. Press the "Enter" key to open a new Command Prompt window.

Type "diskpart" at the command prompt and press "Enter."

Type "list disk" at the DISKPART prompt and press "Enter" to view a list of the disk drives installed. If you only have one internal hard drive and the connected USB flash drive, the primary system drive is labeled "Disk 0" in the list and the USB flash drive appears as "Disk 1."

Type "select disk 1" at the command prompt and press "Enter" or use the disk number for your USB drive if you have more than one internal drive.

Type "clean" at the DISKPART prompt and wait for Windows to wipe the drive contents and delete all active partitions on it.

Type "select partition 1" at the DISKPART prompt and press "Enter." Type "active" at the prompt, and the press "Enter" again to make the partition on the USB flash drive active so that you can make it bootable.

Type "format fs=fat32" at the DISKPART prompt and press "Enter." Wait as Windows formats the USB flash drive. The DISKPART prompts displays a confirmation message once the format process completes.

Type "assign" at the DISKPART prompt and press "Enter." The prompt displays a message indicating Windows assigned a drive letter to the drive successfully.

Type "exit" at the DISKPART prompt to exit the utility and close the Command Prompt window.

Open Windows Explorer and browse to the folder that contains the boot files for the utility or operating system you want to install. Copy the files to the USB flash drive.

Restart the computer and wait for the system to boot from the USB flash drive. Perform repairs on the machine or install another operating system on the computer as needed.


  • When you format the USB drive, you are performing a full format and not a quick one like most you perform in Windows. Therefore, the format process may take a half an hour or more depending on the size of your USB flash drive.
  • If your goal for making a flash drive bootable is for the sole purpose of installing Windows 7 from it, you can download a special software tool that does all the work for you from the Microsoft Store (link in Resources). Simply download the tool, install it and then connect your flash drive to the computer. Run the tool and the utility formats the drive and makes it bootable so you can install Windows 7 from it rather from a DVD.


  • You must set up your system BIOS to boot from a USB device before the computer can boot from the flash drive. To enter the BIOS, press the "F1," "F2" or "Delete" key as soon as you see the initial boot screen or manufacturer logo and enter the BIOS password if prompted. You can usually find the USB boot option under the "Advanced" or "Advanced Settings" menu option on the BIOS Setup screen.

About the Author

Jeff Grundy has been writing computer-related articles and tutorials since 1995. Since that time, Grundy has written many guides to using various applications that are published on numerous how-to and tutorial sites. Born and raised in South Georgia, Grundy holds a Master of Science degree in mathematics from the Georgia Institute of Technology.

Photo Credits

  • Jeffrey Hamilton/Digital Vision/Getty Images