How to Reinstall Windows with a USB Drive

Here is how to reinstall Windows with USB in short: create a bootable drive with Microsoft's Media Creation Tool on any working PC, boot the target PC from that USB, delete the old partitions on the system drive, and install. It takes about an hour, wipes the drive, and Windows normally reactivates by itself once online if the PC had a digital licence.

What Do You Need Before Reinstalling Windows from USB?

You need a blank USB drive of at least 8 GB, a working PC with internet access, a valid licence, and a backup of your files. The checklist below covers everything worth preparing first.

Check your activation status first in Settings → System → Activation. If it says Windows is activated with a digital licence linked to your Microsoft account, reactivation after the reinstall is usually automatic. A digital licence is a record held by Microsoft's activation servers that ties your licence to your hardware, so the same PC is recognised again after a fresh install.

How Do You Create a Bootable Windows USB?

The simplest way is Microsoft's free Media Creation Tool, which downloads the current version of Windows and writes it to the USB for you. For Windows 11, that is currently version 26H2. The tool needs a 64-bit PC and cannot make media for Arm-based devices.

1. Plug the USB drive into a working PC and copy off anything you want to keep, because it will be erased.
2. Open Microsoft's Windows 11 download page and select Download Now under Create Windows 11 Installation Media.
3. Run the tool and accept the licence terms.
4. Choose your language and edition, or keep Use the recommended options for this PC ticked.
5. Select USB flash drive, pick your drive, and select Next.
6. Wait for the download and verification to finish, then select Finish.

If you are unsure whether to use this tool, the Installation Assistant or an ISO, our comparison of the Windows 11 Update Assistant, Installation Assistant and ISO explains which one suits each situation.

How Do I Boot from USB on Windows 10 or Windows 11?

You boot from USB either through a one-time boot menu key or through Windows' Advanced startup options. The method depends on whether the PC still starts normally.

If Windows still starts

1. Insert the USB drive.
2. Open Settings → System → Recovery (on Windows 10: Settings → Update & Security → Recovery).
3. Next to Advanced startup, select Restart now.
4. Choose Troubleshoot → Advanced options → UEFI Firmware Settings, select Restart, and set the USB drive first in the boot order.

If Windows does not start

Switch the PC on and press the manufacturer's boot menu key straight away. It varies by brand; common keys include F12, F11, F8 and Esc, and the PC maker's support site lists the right one. Pick the USB drive from the list.

Modern PCs use UEFI firmware with Secure Boot, a feature that only allows trusted, signed boot software to start. Microsoft's own installation media is signed, so it normally boots with Secure Boot on. If a PC refuses to start from the USB, check the boot order before touching Secure Boot; our guide on how to check if Secure Boot is enabled shows where to find the setting.

How Do You Reinstall Windows from the USB Step by Step?

Once the PC boots from the USB, Windows Setup walks you through the clean install. These steps follow Microsoft's guide to reinstalling Windows with installation media.

1. Choose your language, time format and keyboard, then select Next.
2. Select Install Windows 11 and confirm that you understand everything will be deleted.
3. When asked for a product key, enter it, or select I don't have a product key if the PC already has a digital licence.
4. If asked, choose the edition that matches your licence, for example Windows 11 Home or Pro.
5. Accept the licence terms.
6. On the disk screen, delete each partition on Disk 0 until only Disk 0 Unallocated Space remains. Do not touch partitions on any other disk.
7. Select the unallocated space, then select Next and Install.
8. Remove the USB drive when the PC restarts for the first time, or leave it in if your boot order is set to the internal drive first.
9. Complete the setup screens and sign in with your Microsoft account.

Choosing the right edition is important because of cause and effect: a Windows 11 Pro digital licence will not activate a Home installation, and the reverse is also true. If you choose the wrong edition, Windows installs but stays unactivated until you reinstall the correct one or upgrade.

How Does Activation Work After a USB Reinstall?

Activation is usually automatic once the PC connects to the internet, provided you reinstalled the same edition on the same hardware. You can confirm it in Settings → System → Activation.

The licence type affects what happens next. An OEM licence is tied to the PC it first activated on, so a reinstall on that same PC is fine, but it does not move to a new motherboard. A retail licence can be moved to a new PC once it is removed from the old one. Our guide to Windows OEM vs retail licences covers the rules in detail. If you see an error code instead, see Windows activation errors explained.

What About Drivers After a Clean Install?

Windows Update installs most drivers automatically once the PC is online. Open Settings → Windows Update, select Check for updates, and then look under Advanced options → Optional updates for extra driver packages. If a device such as Bluetooth is still missing, download the driver from the PC or motherboard maker's support page and install it. Reinstalling a Bluetooth driver on Windows 11 is done in Device Manager: right-click the device, choose Uninstall device, restart, and Windows reloads it.

A Common Mistake We See

The most common problem we see is choosing the wrong edition during setup. Someone with a Home digital licence installs Pro, or the reverse, and then finds Windows will not activate even though nothing has changed on the hardware.

The second is forgetting to link the digital licence to a Microsoft account before a reinstall, then replacing a component and finding activation fails. Linking first gives you the Activation troubleshooter as a fallback. If you need a fresh licence, our Windows collection has keys with instant email delivery, a 30-day money-back guarantee and a lifetime replacement warranty, and our support team can help with activation.

Frequently Asked Questions

How do I reinstall Windows with a USB without losing files?

Do not boot from the USB. Instead, open the USB drive in File Explorer while Windows is running, run setup.exe, select Change what to keep, and choose Keep personal files and apps. This repairs Windows in place. Booting from the USB performs a clean install, which deletes everything.

How do I boot from USB on Windows 10?

Insert the USB, then open Settings → Update & Security → Recovery and select Restart now under Advanced startup, then open UEFI Firmware Settings and put the USB first. If Windows does not start, press the manufacturer's boot menu key, often F12, F11 or Esc, as the PC switches on.

Do I need a product key to reinstall Windows?

Not if the PC already has a digital licence for the same edition. Select I don't have a product key during setup, and Windows activates once online. You need a product key if the PC never had an activated copy of that edition or after major hardware changes.

What size USB do I need to reinstall Windows 11?

Microsoft asks for a blank USB drive of at least 8 GB. Any data on it is erased while the Media Creation Tool writes the setup files. A USB 3.0 drive is faster to create and install from, but USB 2.0 drives also work.

How do I safely eject the USB from Windows after creating it?

Select the USB icon in the taskbar notification area, choose Eject next to the drive, and wait for the safe-to-remove message. In File Explorer you can also right-click the drive and choose Eject. Ejecting first avoids corrupting files the tool has just written.

Can I reinstall Windows 7 from USB?

Windows 7 has been out of support since January 2020 and receives no security fixes, so it is not safe to use online. If your PC meets the requirements, install Windows 11 instead. Older hardware that cannot run Windows 11 is better served by a supported alternative than by Windows 7.

Conclusion

Knowing how to reinstall Windows with USB comes down to three things: a drive made with the Media Creation Tool, booting from it correctly, and choosing the edition that matches your licence. If you need a licence for the fresh install, a Windows 11 Pro product key activates online in minutes.

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