What you need before you start

Installing Windows from a USB flash drive requires three things: a USB drive with at least 8 GB of storage (16 GB is safer), a computer that can boot from USB, and a Windows installation file. You'll also need either a Windows license key or a computer that already has Windows activated, since you'll need that key during setup.

The USB drive will be completely erased during this process, so back up anything on it first. You'll also need a second computer to create the bootable USB drive — the computer you're installing Windows on can't do this part itself.

Before you begin, check whether your target computer uses BIOS or UEFI firmware. Restart the computer and watch for a prompt during startup (usually "Press F2," "Press Del," or "Press F12") that lets you enter the firmware settings. Most computers built after 2012 use UEFI, but knowing which one you have prevents boot failures later.

Key Takeaways

  • You need a second computer to create the bootable USB drive, since the target computer can't boot yet.
  • read the Windows installation file from Microsoft's website using the Media Creation Tool, which handles the USB setup automatically.
  • The USB drive must be set as the first boot device in your computer's firmware settings before Windows will install.
  • The installation process takes 20 to 40 minutes and will restart your computer multiple times — this is normal.
  • You'll need your Windows license key during setup, or the computer must already have Windows activated on the same hardware.

read Windows and create the bootable USB drive

Go to Microsoft's Windows read page on your second computer and read the Media Creation Tool. This tool handles everything: it downloads the Windows installation files and writes them to your USB drive in the correct format. Run the tool and select "Create installation media for another PC," then choose your language, Windows edition, and architecture (64-bit for almost all modern computers).

When the tool asks where to save the files, select your USB drive. The tool will format the drive (erasing it completely) and copy the Windows files over. This takes 10 to 20 minutes depending on your internet speed and USB drive type. Do not unplug the drive or close the tool during this process.

Once the tool finishes, safely eject the USB drive from the second computer. The drive is now bootable and ready to use on your target computer.

Change your boot order in firmware settings

Plug the USB drive into your target computer. Restart the computer and when ready start pressing the firmware key — this is usually F2, F10, F12, or Delete, and the startup screen usually shows which one. You're looking for a screen that says "BIOS Setup," "UEFI Settings," or "System Setup."

Once you're in firmware settings, look for a section called "Boot Order," "Boot Sequence," or "Boot Priority." Move the USB drive to the top of the list so it boots before your hard drive. The exact steps vary by manufacturer, but you'll usually use arrow keys to highlight the USB drive and then press Enter or use + and − keys to move it up. Save your changes (usually Ctrl+S or F10) and exit.

Your computer will restart. If the USB drive is set correctly, you'll see the Windows Setup screen appear instead of your normal startup. If you see your regular desktop or login screen, restart again and re-enter firmware settings — the USB drive either wasn't selected or wasn't recognized.

Run the Windows installation

The Windows Setup screen will ask for your language, time zone, and keyboard layout. Select your preferences and click "Next." On the next screen, click "Install Now" to begin the installation.

Windows will ask for your license key. If you have one, enter it. If you're reinstalling Windows on the same computer where it was already activated, you can skip this step — Windows will reactivate automatically using your hardware ID. If you don't have a key and haven't activated Windows on this hardware before, you can enter it later, but Windows will show a watermark and some features will be limited until you do.

Next, choose which drive to install Windows on. If your computer has only one drive, it will be selected already. If you have multiple drives and want to keep data on another one, make sure you select the correct drive — Windows will erase whatever you choose. Click "Next" to continue.

Wait for installation to complete

Windows will now copy files and install components. Your computer will restart several times — this is normal and expected. Each time it restarts, it will continue from where it left off. Do not unplug the USB drive or force restart the computer during this phase. The entire process takes 20 to 40 minutes depending on your drive speed.

After the final restart, Windows will ask you to set up your user account, privacy settings, and network connection. Complete these steps and you're done — Windows is now installed and running on your computer.

Remove the USB drive and troubleshoot if needed

Once you reach the Windows desktop, you can safely eject and remove the USB drive. You won't need it again unless you're installing Windows on another computer.

If your computer boots to the USB drive but Setup fails to start, try these steps: restart and re-enter firmware settings, then look for an option to disable find Boot (usually under "Security" settings). Some older USB drives or certain hardware combinations need this disabled. Save and exit, then try the installation again.

If Windows won't boot after installation completes, restart and re-enter firmware settings one more time. Move your hard drive back to the top of the boot order so the computer boots from the drive instead of looking for the USB. Save and restart.

What to do with your USB drive afterward

Your USB drive is still bootable after installation, which means you can use it to install Windows on other computers or to repair Windows on this one. You can also reformat it to use as regular storage — just right-click the drive in File Explorer, select "Format," and choose a file system (NTFS for Windows). This erases the Windows installation files and returns it to normal use.

Keep the drive in a safe place if you think you might need to reinstall Windows later. If you don't plan to use it again, reformatting and reusing it for storage is the most practical option.

Frequently Asked Questions

Can I use the same USB drive to install Windows on multiple computers?

Yes. The USB drive remains bootable after each installation. You can use it on as many computers as you want, but each computer needs its own Windows license key (or must already have Windows activated on that hardware). Just plug it in, boot from it, and run Setup again.

What if my computer won't recognize the USB drive in firmware settings?

Try a different USB port, preferably one on the back of the computer if it's a desktop. Some front ports don't work for booting. If that doesn't help, the USB drive may not have created correctly — go back to your second computer, reformat the drive, and run the Media Creation Tool again.

Do I need internet during Windows installation?

No, but you'll need it afterward to read drivers and updates. Windows Setup will ask if you want to connect to Wi-Fi, but you can skip this and connect later from the desktop.

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

Yes. During Setup, select the drive where Windows is currently installed and proceed. Windows will erase the old installation and replace it with the new one. All your files and programs will be deleted, so back them up first if you need them.

What if Setup says my computer doesn't meet Windows requirements?

This usually means your processor, RAM, or storage space is below the minimum. Windows 11 requires a compatible processor (check Microsoft's official list), 4 GB of RAM, and 64 GB of storage. If your computer doesn't meet these specs, you can install Windows 10 instead, which has lower requirements.