How to create a bootable Windows 10 USB drive

Microsoft has officially introduced Windows 10, making the new operating system available as a free upgrade, in the first year, to Windows 7 and Windows 8.1 users. Those who cannot take advantage of this deal will have to purchase Windows 10, which is now offered on USB drives, on top of DVDs and digital downloads.

Bootable USB drives are a better option than DVDs, as they can be used on the vast majority of devices in use today, including slim ultrabooks which do not have optical drives. They are also much faster, so the time it takes to install Windows 10 is significantly lower, and pocketable, allowing you to easily carry one wherever you need. If you do not have a bootable Windows 10 USB drive, this detailed how-to guide takes you through all the steps involved in creating your own flash installation media.

The Essentials

First off, you will need a USB drive. The minimum capacity is 4 GB, and I recommend using a drive that is decently fast, so the time it takes to complete the whole process is minimized. Keep in mind that, no matter which path you take, all the files on the USB drive will be erased, so make sure to back everything up. Alternatively, you can use a microSD or SD card, which works just as well based on my experience.

You will also need a Windows 10 ISO, which can be downloaded from Microsoft's servers using the dedicated tool that Microsoft has released (more on it in the section below). Get this version for the 32-bit Windows 10 or this version for the 64-bit Windows 10. You may also be able to download it directly from this page, or MSDN.

In order to create the bootable Windows 10 USB drive, you also need a Windows PC and an archiving tool like 7-Zip or WinRAR if you do not yet have one installed. And, in order to actually get the latest operating system up and running on your device, you will also need a valid Windows 10 product key.

If you have a valid Windows 7 or Windows 8.1 license you will first have to upgrade to Windows 10, in order to perform a clean install, from a bootable USB drive, later. Otherwise the key you have entered may not be seen as valid during the setup phase.

Your Options

There are a couple of ways you can create a bootable Windows 10 USB Drive. The official method involves using the aforementioned dedicated tool to download the necessary files from Microsoft's servers and create the installation media. My colleague Wayne Williams has explained how you can do this in this article. This works best if you do not have the Windows 10 ISO on your PC.

If you have the Windows 10 ISO on your PC, you have two options. The method that I prefer involves writing a few lines in a command prompt window. This gives you more control over the process, and you also get to learn something new. The other method requires the use of a dedicated (third-party) tool that will handle the contents of the ISO and prepare the USB drive automatically.

Creating the Bootable Windows 10 USB Drive

First, I will explain how you can manually create a bootable Windows 10 USB drive. Here is where the archiving tool comes in handy, as you will have to use it to extract the contents of the ISO in a folder on your Windows PC. After this is complete, plug in the USB drive and follow the next steps to create the installation media:

1. Open a Command Prompt window. To do this, open Run (Windows key + R will do the trick; alternatively, it can be found in the Start menu), type "cmd" and then press the OK button.
2. Use the "diskpart" command to open the disk partitioning software. Accept the UAC prompt, if asked, to continue.
3. Use the "list disk" command to display the list of storage drives -- it will reveal all the HDDs, SSDs, USB drives, and so on, that are attached to your PC.
4. Identify the disk number of the USB drive that you are using -- you can easily find it by looking at the size column; it is usually the last one that is listed.
5. Use the "select disk X" command to select the USB drive -- "X" is the disk number of your USB drive, and it is shown in the first column.
6. Use the "clean" command to erase everything on the USB drive.
7. Use the "create partition primary" command to create a primary partition on the USB drive.
8. Use the "select partition 1" command to select that partition.
9. Use the "active" command to make said partition active.
10. Use the "format fs=fat32 quick" command to format it as FAT32, using the Quick (fast) routine.
11. Use the "assign" command to assign a drive letter to the USB drive -- it will show up as a drive under My Computer.
12. Copy the extracted contents of the Windows 10 ISO to the USB drive

For the visual step-by-step guide, check out the slideshow that is embedded below.

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If you want to use a dedicated tool for the job, you should know that there are many options available. I recommend sticking with Microsoft's Windows USB/DVD Download Tool, which, even if it does not offer any advanced options, works fine for this purpose. After installing it, here is what you need to do:

1. Open the tool, click the Browse button and select the Windows 10 ISO file.
2. Select the USB drive option.
3. Select your USB drive from the dropdown menu.
4. Hit the Begin Copying button to kick off the process.

What Next?

Now that you have created the bootable Windows 10 USB drive, you can go to the next step: installing the operating system. How do you initiate the setup process?

Your PC must be configured to boot from a USB drive, which can be selected from the boot menu or BIOS/UEFI. To enter BIOS/UEFI you have to press a dedicated key; same goes for the boot menu. Both can be entered right after powering up the device or restarting it.

After performing this step, your PC will automatically boot from the USB drive and take you straight to the Windows 10 setup. From there on, it is business as usual: enter your product key, if asked, and select where you want to install the operating system.

Photo Credit: Mario Lopes/Shutterstock