What you need before you start

To install Windows from a USB drive, you need three things: a USB drive with at least 8 GB of storage space, a computer where you can download the Windows installation files, and the computer where you want to install Windows. The USB drive will be erased during this process, so back up anything on it first.

You also need a Windows product key or a valid Windows license. If you're reinstalling Windows on a computer that already had it, the license may be tied to your hardware and activate automatically. If you're installing on a new computer or a different machine, you'll need to provide a key during setup or have a Microsoft account linked to a Windows license.

Finally, you should know your computer's boot order settings. Most modern computers let you press a key during startup (often F12, Esc, or Del, depending on the manufacturer) to choose which device to boot from. Check your computer's manual or manufacturer website if you're unsure which key to press.

Key Takeaways

  • Download the Windows installation tool from Microsoft's website on a different computer, then use it to create a bootable USB drive.
  • Insert the USB drive into the computer where you want to install Windows, restart it, and press the boot menu key during startup to select the USB drive.
  • Follow the Windows Setup wizard to choose your language, edition, and installation drive, then let the installation complete without interrupting power.
  • After installation finishes, remove the USB drive and let Windows install drivers and updates, which may require a restart.
  • You'll need a Windows product key to activate Windows, though some licenses activate automatically based on your hardware.

Downloading Windows and creating the bootable USB

Go to Microsoft's Windows download page on any computer with internet access. If you're installing Windows 11, download the Windows 11 Installation Assistant or the Media Creation Tool. If you're installing Windows 10, use the Windows 10 Media Creation Tool. Both are free and available directly from Microsoft.

Run the tool you downloaded. It will ask you to accept the license terms, then prompt you to choose whether you're upgrading this computer or creating installation media for another computer. Select "Create installation media for another PC." The tool will then ask you to choose the language, edition (Home or Pro, for example), and architecture (64-bit or 32-bit). For most modern computers, choose 64-bit.

When the tool asks where to save the installation files, select your USB drive from the list. The tool will download the Windows files and write them to the USB drive, which takes 10 to 30 minutes depending on your internet speed. Do not remove the USB drive or close the tool during this process. When it finishes, you'll see a message confirming the media is ready.

Inserting the USB and accessing the boot menu

Insert the USB drive into a port on the computer where you want to install Windows. Restart that computer. As soon as it begins to power on, start pressing the boot menu key repeatedly — usually F12, Esc, Del, or F2, depending on whether it's a Dell, HP, Lenovo, Asus, or another brand. You should see a menu appear with a list of devices you can boot from.

Look for an entry that mentions your USB drive by name or says "USB Device" or "Removable Media." Select it and press Enter. The computer will boot from the USB drive instead of the hard drive, and you'll see the Windows Setup screen appear within a few seconds.

If you don't see a boot menu, you may have pressed the wrong key or pressed it too late. Restart the computer and try again, pressing the key as soon as you see the manufacturer's logo. If you still don't see a menu, check your computer's manual or the manufacturer's support website for the correct key for your specific model.

Running the Windows Setup wizard

The Windows Setup screen will ask you to choose your language, time zone, and keyboard layout. Select the options that match your location and preferences, then click Next. On the next screen, click "Install now" to begin the installation process.

You'll be asked to enter your Windows product key. If you have one, type it in. If you don't have a key yet, you can click "I don't have a product key" and continue — Windows will let you install and use it for a limited time, and you can enter a key later. If your computer previously had Windows and you're reinstalling it, the license may activate automatically without requiring you to enter a key.

Next, you'll see a list of your computer's drives. Select the drive where you want to install Windows. If you're replacing an existing Windows installation, select the drive that currently contains Windows (usually labeled "C:" or "Drive 0"). If you want to erase everything on that drive first, right-click it and select "Delete" to remove all partitions, then select the unallocated space and click Next. Setup will create a new partition and install Windows there.

Completing the installation

Once you've selected your drive, click Next and Windows Setup will begin copying files and installing the operating system. This process takes 15 to 30 minutes and involves several automatic restarts. Do not turn off the computer, unplug it, or remove the USB drive during this time. The computer may appear to be stuck or show a black screen for a minute or two — this is normal.

When the installation reaches the point where it's ready to restart, you may see a message asking you to remove the USB drive. If you see this, remove the USB drive before the computer restarts. If you don't see this message, the USB drive will be ignored on the next restart anyway, and Windows will boot from the hard drive instead.

After the final restart, Windows will load for the first time. You'll see the Windows Setup screen again, asking you to choose your region, keyboard layout, and whether to connect to a network. Follow these prompts to complete the initial setup. Windows will then download and install drivers for your hardware and any available updates, which may trigger additional restarts.

Activating Windows after installation

Once Windows is fully installed and updated, you'll need to activate it. If your computer previously had Windows 10 or 11 and you're reinstalling the same edition on the same hardware, Windows will usually activate automatically within a few minutes. You can check the activation status by going to Settings, then System, then About, and looking for "Activation status."

If Windows doesn't activate automatically, you'll see a message saying "Windows is not activated." You can still use Windows, but you'll see a watermark on your desktop and won't be able to customize some settings. To activate, go to Settings, System, About, and click "Activate" or "Go to Settings." You'll be asked to enter a product key or sign in with a Microsoft account that has a Windows license tied to it.

If you don't have a product key and your computer is new, you may need to purchase one from Microsoft or an authorized retailer. Keys are available for both Home and Pro editions and typically cost between $100 and $200, though prices vary by region and retailer.

Troubleshooting common problems

If the computer doesn't boot from the USB drive, the most common cause is that you pressed the boot menu key too late or too early. Restart and try again, pressing the key as soon as you see the manufacturer's logo but before Windows starts to load. If you still can't access the boot menu, your computer may have Secure Boot enabled, which prevents booting from external media. Restart, enter the BIOS or UEFI settings (usually by pressing F2 or Del during startup), and look for a Secure Boot option. Disable it, save, and restart.

If Windows Setup says "No drives were found," your computer may not recognize the drive where you want to install Windows. This usually happens with very new computers that need special drivers for newer storage hardware. You may need to download chipset drivers from your computer manufacturer's website, copy them to a second USB drive, and load them during Setup when prompted. Check your manufacturer's support page for Windows installation help specific to your model.

If the installation fails partway through with an error message, note the error code and restart the computer. Try the installation again from the USB drive. If it fails again at the same point, the USB drive may be corrupted. Go back to the computer where you created it, download the Media Creation Tool again, and create a new bootable USB drive on a different USB device.

Frequently Asked Questions

Can I install Windows on a Mac?

Not directly — Macs use a different processor architecture than most PCs. You can run Windows on a Mac using virtualization software like Parallels Desktop or VMware Fusion, but these run Windows inside macOS rather than replacing it. Newer Macs with Apple Silicon chips cannot run Windows at all through these methods. If you need to run Windows natively, you'll need a PC.

What if I don't have another computer to create the USB drive?

You'll need access to another computer with internet to download the Windows installation tool and create the bootable USB. If you don't have one, you can use a computer at a library, a friend's house, or an internet café. The process takes about 30 minutes total, including download time.

Will installing Windows erase all my files?

Yes, if you select the drive where your files are stored and proceed with installation, everything on that drive will be erased. Before you start, back up any files you want to keep to an external drive, cloud storage, or another computer. If you want to keep your old Windows installation alongside the new one, you can create a separate partition on your drive and install Windows there instead.

Do I need internet during the Windows installation?

You don't need internet to install Windows itself, but you'll need it afterward to download drivers and updates. If your computer doesn't have built-in WiFi or Ethernet, bring it near a WiFi network or connect an Ethernet cable after installation finishes. Windows will automatically search for and install drivers for most hardware once it's connected.

Can I reuse the USB drive after Windows is installed?

Yes. Once Windows is fully installed and running, you can erase the USB drive and use it for other purposes. Simply plug it into any computer, right-click the drive in File Explorer or Finder, and select "Format" to erase it. After that, it will work like a normal USB drive again.