If you’re trying to install Windows on a laptop that doesn’t have a DVD drive, or you want a portable installation tool that you can use on a lot of computers, creating a bootable USB Windows installation drive may be the answer you’re looking for. All modern versions of Windows can be easily installed from a USB drive, as long as you have a valid Windows product key. You’ll need a USB flash drive that has at least 4 GB of storage. For Windows 7 and Vista, you’ll need an installation disc or an ISO image file of the installation disc as well.

1. Ensure that your flash drive is empty and has at least 4 GB of space. Any files on your flash drive will be deleted when the Windows installation files are added. Your USB drive will need to have at least 4 GB of storage in order to create the installer.
2. Download the Windows 10 Media Creation Tool. This utility allows you to turn your flash drive into a Windows 10 installation drive. You don’t need to be using Windows 10 to use this tool. You can download this tool for free from Microsoft at microsoft.com/en-us/software-download/windows10.
   Nearly all newer computers are 64-bit, but you can check to determine what version of Windows you are currently running in your System Properties window. Click here for more details.
   You’ll need to have administrator access to use this tool.
3. Run the media creation tool and select “Create installation media for another PC”. You’ll be asked to select what version of Windows 10 you want to download. If you are upgrading from a Home or Starter version of Windows 7 or 8, select “Windows 10 Home”. If you are upgrading from a Professional or Ultimate version of Windows 7 or 8, select “Windows 10 Pro”. If you aren’t upgrading from Windows 7 or 8, select whichever version of Windows you purchased a product key for.
   Upgrading from Windows 7 or 8 is free until July 2016.
4. Select “USB flash drive”. This will allow the tool to automatically format your flash drive so that you can boot from it and install the Windows files. Any files already on the flash drive will be deleted, so make sure you’ve saved anything important.
5. Wait for the download and creation process to complete. The tool will need to download nearly 4 GB of data, which can take a significant amount of time on slower connections. Click “Finish” after the download is complete.
6. Upgrade a Windows 7 or 8 computer to register before installing Windows 10 (upgrading only). If you’re creating this flash drive to install Windows 10 on a computer that is currently running Windows 7 or 8 in order to take advantage of the free upgrade, you must use the Upgrade utility first before performing a clean install. This registers your computer with Microsoft to make up for the fact that you don’t have a product key. If you don’t upgrade first, you won’t be able to activate Windows 10 unless you purchase a product key or reinstall your old version of Windows and try again.
   Run the Windows 10 Media Creation Tool on the computer that you want to upgrade to Windows 10.
   Select “Upgrade this PC now” and follow the prompts to install Windows 10. You won’t lose any of your files. After upgrading to Windows 10, you can use your new flash drive to perform a clean install at any time on that PC.
7. Insert the flash drive in the computer you want to install Windows on. Once your flash drive is ready, you can use it to start installing Windows 10. Make sure that if you’re trying to upgrade an older version of Windows, you have a valid Windows 10 product key or have already registered the computer using the free upgrade method in the previous step.
8.  

   Boot your computer from the USB drive. The process for this varies a lot depending on the computer that you are using. Traditionally, you would open the BIOS menu and change the order of drives in the BOOT menu. Newer computers use UEFI instead of BIOS, which needs to be accessed in a special way if you’re using Windows 8.
   Reboot your computer and look for the BIOS or BOOT menu key when the manufacturer logo appears. Press this key to open the menu and change your boot order. The setup key is typically F2, F10, F11, or Del. Make sure that the USB drive is listed as the primary boot device.
   If your computer boots directly into Windows 8 without showing the manufacturer logo, open the Charms bar (⊞ Win+C) and select “Settings”. Click the “Change PC settings” option and then select “Update and recovery”. Select the “Recovery” option and click “Restart now” under “Advanced Startup”. In the boot menu, select “Troubleshoot” and then “Advanced options”. Click the “UEFI Firmware Settings” to open your UEFI menu. You can then open the BOOT menu and change the order so that the USB drive is the primary drive.

9. Press a key to start the installation. You’ll see a message on your screen prompting you to press a key to boot from “CD or DVD”. This is correct and will display if you’ve selected your USB drive as the primary boot device.
10. Select your language and input settings. Before Windows 10 installs, you’ll be prompted to select your language and keyboard settings. The language that you install will be your default base language.
11. Click “Install now” to begin the installation. The installation process will begin.
12. Skip the product key window if installing a computer that already upgraded. When prompted to enter a product key, click the “Skip” or “Do this later” option. After installation, Windows 10 will automatically check with Microsoft to see if the Windows 10 upgrade was activated for that computer. If you purchased a product key for Windows 10, enter it now.