How to Install Windows From Your Computer's BIOS

What happens when you boot from BIOS

When you install Windows from BIOS, you are telling your computer to start up using an external device — usually a USB drive or DVD — instead of loading the operating system already on your hard drive. BIOS is the firmware that runs before Windows loads, so it controls which device your computer checks first for an operating system to start. By changing this order in BIOS, you can make your computer read the Windows installation files from the USB drive before it tries to load from the hard drive.

This process is necessary when you are installing Windows for the first time, replacing a damaged Windows installation, or moving Windows to a new hard drive. The computer cannot install Windows on itself while Windows is already running — it needs to start from external media and run the installer as the primary program.

The steps differ slightly depending on whether your computer uses traditional BIOS or the newer UEFI firmware, but the goal is the same: make your computer boot from the installation media instead of the existing hard drive.

Key Takeaways

You need a USB drive with at least 8 GB of space containing Windows installation files, which you can create on another computer using the Windows Media Creation Tool.
Restart your computer and press the BIOS key — usually Delete, F2, F10, or F12 — when ready after power-on, before Windows starts to load.
In BIOS, find the Boot Order or Boot Priority section and move your USB drive above the hard drive in the list, then save and exit.
Your computer will restart and begin loading the Windows installer from the USB drive, where you choose your language, disk, and installation options.
After Windows finishes installing, remove the USB drive and restart your computer to complete the setup process.

Creating a Windows installation USB drive on another computer

Before you can boot from BIOS, you need a USB drive with Windows installation files on it. You must create this on a different computer that already has Windows running, because you cannot create the installation media on the computer you are trying to install Windows on.

Go to the Microsoft Windows read page on a working computer and read the Windows Media Creation Tool. Insert a USB drive with at least 8 GB of empty space, open the Media Creation Tool, and select "Create installation media for another PC." Choose your language and Windows version, select USB flash drive as the media type, and let the tool copy the installation files. This takes 10 to 20 minutes depending on your internet speed and USB drive speed. When it finishes, safely eject the USB drive.

Keep this USB drive with you — you will plug it into the computer where you want to install Windows.

Finding and entering your computer's BIOS

The BIOS key is the button you press when ready after turning on your computer, before Windows starts to load. The key varies by computer manufacturer: Dell and Lenovo usually use F2, HP and Compaq use F10, Asus uses Delete, and some older computers use F12. If you are unsure, restart your computer and watch the first screen that appears — it usually shows "Press [key] to enter Setup" or "Press [key] for BIOS."

Turn off your computer completely. Turn it back on and when ready begin pressing your BIOS key repeatedly — do not wait, and do not let Windows start. You should see a blue or black screen with white text showing BIOS settings. If Windows starts loading instead, restart and try again, pressing the key faster.

Once you are in BIOS, you will see menus with options like Main, Advanced, Boot, and Security. You need to find the Boot section, which controls the order in which your computer checks devices for an operating system.

Changing the boot order to prioritize your USB drive

Look for a menu option called Boot Order, Boot Priority, Boot Sequence, or straightforward Boot. Use your arrow keys to navigate to this section — the mouse does not work in BIOS. Once you open the Boot section, you will see a list of devices: your hard drive (usually labeled as a brand name like Samsung or Western Digital), your USB drive (usually labeled with the USB drive brand or "USB Device"), and possibly a DVD drive.

Move your USB drive to the top of the list using the arrow keys and the + or - keys, or by pressing a key like F5 or F6 to move items up and down. The exact method depends on your BIOS version, but the screen usually shows instructions at the bottom. Your goal is to make the USB drive appear first, so your computer checks it before the hard drive.

After you have moved the USB drive to the top, look for a Save and Exit option, usually at the bottom of the screen or in a separate menu. Press Enter to save your changes. Your computer will restart.

Starting the Windows installation from your USB drive

After you save and exit BIOS, your computer restarts and begins reading from the USB drive. You should see a black screen with white text saying "Press any key to boot from CD or DVD" or similar — press any key on your keyboard. The Windows Setup screen then appears, showing options for language, time, and keyboard layout.

Select your language and keyboard layout, then click Next. On the next screen, click "Install Now" to begin the installation process. Windows will ask you where to install — you should see your hard drive listed. Select it and click Next. Windows then copies files and installs itself, which takes 15 to 30 minutes. Your computer may restart several times during this process, which is normal.

Do not remove the USB drive until Windows finishes installing and asks you to set up your user account. Once you reach the screen where Windows asks for your name and password, the installation is complete and you can safely remove the USB drive.

Troubleshooting if your computer does not boot from the USB drive

If your computer starts Windows from the hard drive instead of from the USB drive, the boot order change did not save. Restart, enter BIOS again, and check that the USB drive is still at the top of the boot list. Some BIOS versions require you to press a specific key to confirm the change before saving — check the on-screen instructions.

If the USB drive does not appear in the boot list at all, it may not be inserted fully, or the Windows installation files may not have copied correctly. Remove the USB drive, restart your computer, and enter BIOS again to confirm. If it still does not appear, create the installation media again on another computer using the Windows Media Creation Tool.

If you see an error message like "No bootable device found" or "Boot failure," the USB drive may be damaged or the installation files are corrupted. Try creating the installation media again on a different USB drive. If you have access to a DVD drive, you can also read the Windows ISO file and burn it to a DVD instead of using a USB drive.

What to do after Windows installation completes

Once Windows finishes installing and you reach the account setup screen, remove the USB drive and restart your computer. Your computer will now boot from the hard drive where Windows is installed. Windows will ask you to create a user account, set a password, and choose privacy settings. Complete these steps to finish the installation.

After setup is complete, you should change your BIOS boot order back to prioritize the hard drive, so your computer boots normally in the future. Restart, enter BIOS, move the hard drive back to the top of the boot list, save, and exit. This is not required for Windows to work, but it prevents accidental boots from the USB drive if it is plugged in.

Frequently Asked Questions

Can I use a DVD instead of a USB drive to install Windows?

Yes, if your computer has a DVD drive. read the Windows ISO file from Microsoft, burn it to a blank DVD using another computer, and insert the DVD into your computer before entering BIOS. Change the boot order to prioritize the DVD drive instead of the USB drive, then save and exit. The installation process is identical.

What if I do not know my BIOS password?

If BIOS is password-protected and you do not know the password, you cannot change the boot order without resetting BIOS. Contact your computer manufacturer or a local repair shop — they can reset BIOS to factory settings. If the computer is yours and you forgot the password, provide proof of ownership to the manufacturer.

Will installing Windows from BIOS erase my files?

Installing Windows erases everything on the drive where you install it. If you want to keep files from the old Windows installation, back them up to an external drive before you start. During installation, Windows asks which drive to install on — make sure you select the correct one.

Do I need to disconnect other USB drives while installing Windows?

It is safer to disconnect other USB drives before you start. If multiple USB drives are plugged in, BIOS might boot from the wrong one, or Windows might install on the wrong drive. Keep only the Windows installation USB drive connected until installation is complete.

Can I install Windows on a computer that already has Windows on it?

Yes. Boot from the USB drive using the same BIOS steps, and during installation, select the hard drive where the old Windows is installed. Windows will overwrite the old installation. You will lose all files and programs from the old Windows, so back up anything you want to keep first.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.