How-toWindowsWindows 10

Windows 10: how to do a clean install from a USB drive

Make a Windows 10 installation USB drive with Microsoft's tool, boot from it and reinstall, with a backup first and the risky screens explained.

  • Updated
  • 45 min
  • Advanced
Applies to
  • Windows 10

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A fresh copy of Windows 10 means wiping the drive you choose. A clean install suits someone who wants a fresh start or whose PC will not run properly, and who is comfortable following careful instructions.

Windows 10 no longer gets free security updates

Support for Windows 10 ended on October 14, 2025. A clean install gives you a tidy system, but it will not receive free security fixes. Plan to move on; see what the end of support means.

Stop and check your backup

A clean install erases everything on the drive you choose: files, programs and settings. Continue only when your files are copied somewhere else and you have opened a few of the copies to check they work. See how to back up your files and make a restore point.

Clean install in five stages5 numbered steps, one under the other. The full text follows the picture.Clean install in five stages1Back upCopy your files and check thecopy opens2Make the USBBuild installation media withMicrosoft's tool3Boot from itOpen the boot menu and pickthe USB drive4InstallChoose Custom and the drivefor Windows5FinishUpdate Windows and restoreyour files
The first stage protects you; the rest follow the screens.
Text version of this diagram
  1. Back up: Copy your files and check the copy opens
  2. Make the USB: Build installation media with Microsoft's tool
  3. Boot from it: Open the boot menu and pick the USB drive
  4. Install: Choose Custom and the drive for Windows
  5. Finish: Update Windows and restore your files

What you need

  • A working computer with internet, to build the USB drive.
  • A blank USB flash drive of at least 8 GB. Everything on it will be deleted.
  • Your backup, and your Microsoft account sign-in if you use one.
  • A laptop plugged into its charger.
  • If the drive is encrypted with BitLocker or device encryption, your recovery key, in case it is asked for. It is usually saved in your Microsoft account.
  • Time. Downloading and installing can take an hour or more, depending on your internet speed and the PC.

You may need a 25-character product key, but not if your PC has a digital license. Many PCs hold a key in their firmware, and Windows uses it automatically if it matches the edition you install. If you are unsure, note down whether the PC was activated before you start (Settings then Update & Security then Activation).

Make the installation USB drive

  1. Plug the blank USB drive into the working computer.
  2. Open Microsoft's Windows 10 download page. Under Create Windows 10 installation media, select Download now.
  3. Right-click the downloaded MediaCreationTool file, select Run as administrator, and accept the license terms.
  4. Select Create installation media for another PC, then Next.
  5. Choose the language, edition and architecture (64-bit or 32-bit). Microsoft's page says to match the PC you are reinstalling.
  6. Choose USB flash drive, select your drive, and wait for the tool to finish. The tool downloads Windows, so keep the computer on.

Official sources only

Use only Microsoft's own tool and page. Never use "free" ISO files, activators or key generators from other sites.

Start the PC from the USB drive

  1. Plug the USB drive into the PC you are reinstalling, then turn the PC on.
  2. Open the boot menu. The key depends on the maker. Microsoft's page lists F2, F12, Delete or Esc. Watch the first screen for a hint, and press the key repeatedly.
  3. Use the arrow keys to select the USB drive and press Enter. You should see the Windows Setup screen. If the old Windows starts instead, restart and try again.
A typical boot menuA monitor showing a simple boot menu on a dark screen with the heading "Boot menu", three choices (internal drive, USB drive and network) with the first highlighted, and a hint bar at the bottom. It has 3 numbered markers, explained in the list under the picture.Boot menuInternal driveUSB driveNetworkEnter: select123A typical boot menu
  1. Each line is a drive the PC can start from
  2. A USB drive often shows its brand name or "USB"
  3. A hint bar lists the keys to move and select
Boot menus differ on every PC. This drawing is typical, not exact.
Text version of this diagram

A monitor showing a simple boot menu on a dark screen with the heading "Boot menu", three choices (internal drive, USB drive and network) with the first highlighted, and a hint bar at the bottom.

  1. Each line is a drive the PC can start from
  2. A USB drive often shows its brand name or "USB"
  3. A hint bar lists the keys to move and select

If the USB drive is not listed

Microsoft's page says Secure Boot may need to be temporarily turned off in the PC's firmware settings (BIOS or UEFI), and suggests asking the PC manufacturer. Changing firmware settings can stop the PC starting if done wrongly, so treat this as a last resort, follow your PC maker's support site for the exact steps, and turn Secure Boot back on afterwards if your PC supports it.

Install Windows 10

  1. On the first Setup screen, set your language, time and keyboard, then select Next and Install now.
  2. If Setup asks for a product key and this PC ran an activated Windows 10 before, select I don't have a product key. Windows should activate itself online later.
  3. If Setup asks which edition to install, choose the one your PC had before, for example Windows 10 Home.
  4. Accept the license terms.
  5. When asked which type of installation you want, select Custom: Install Windows only (advanced). Do not choose Upgrade for a clean install.
  6. On the screen Where do you want to install Windows?, select the main drive or partition for Windows, then select Next. Setup erases the one you pick, so read the note below first.
  7. Wait while Setup copies files. The PC restarts several times. Do not switch it off.

Choose the drive with care

Installing onto a partition that holds your files erases them. If the PC has more than one drive, check sizes carefully. If you are unsure which is which, stop, remove the USB drive, and ask the PC maker. Leave small system partitions alone unless you understand them.

Drives and partitions shown during setupA horizontal bar for one disk, divided left to right into four parts: a small EFI system partition, a large Windows partition, a recovery partition and a hatched block of unallocated space. It has 4 numbered markers, explained in the list under the picture.Disk 01234Drives and partitions shownduring setup
  1. System (EFI) partition: files that start the PC. Leave it alone
  2. Windows partition: the usual place for Windows and your files
  3. Recovery partition: repair tools. Leave it alone
  4. Unallocated space: empty, nothing on it yet
A typical layout. Names and sizes differ between PCs.
Text version of this diagram

A horizontal bar for one disk, divided left to right into four parts: a small EFI system partition, a large Windows partition, a recovery partition and a hatched block of unallocated space.

  1. System (EFI) partition: files that start the PC. Leave it alone
  2. Windows partition: the usual place for Windows and your files
  3. Recovery partition: repair tools. Leave it alone
  4. Unallocated space: empty, nothing on it yet

Check that it worked

  1. When setup finishes, answer the questions for region, network and account.
  2. Open Settings then Update & Security then Windows Update, select Check for updates, and install everything offered. Windows Update can find many missing drivers.
  3. Open Settings then Update & Security then Activation. It should say Windows is activated.
  4. Copy your files back from the backup, then add your programs. See how to install software and apps on Windows 10.

If something goes wrong

Windows says it is not activated

An error message under Activation explains why. A very different PC from the one you started with, or no license on record, can cause this. Do not buy a key from an unknown seller.

A driver is missing (Wi-Fi, sound, display)

Try Windows Update first, then the PC maker's own support site. See how to fix driver problems in Device Manager.

The PC restarts into repair screens

See how to get out of the Windows Automatic Repair loop.

Frequently asked questions

Is a clean install better than Reset this PC?

Not necessarily. Settings then Update & Security then Recovery offers Reset this PC without any USB drive. Try that first if Windows still starts.

Do I need to be online?

You need internet to build the USB drive. Installing itself can run offline, but you need internet afterwards for updates and activation.

Can I reuse the USB drive?

Yes. Once you have finished, you can erase it and use it for other things.

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Official resources used

Pages consulted while preparing this guide. Check them for the latest details.

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