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How to format a disk without an operating system

Disks can be formatted at any time and from any operating system with one exception; you cannot format a disk if your OS is installed on it. You may be able to format a partition on the disk but to format the entire disk, you need to be able to access it from outside the OS that you’re using.

Accessing a disk from outside an operating system, and formatting it requires a tool that can run from the bootloader. There are a few tools that are available but we recommend using a Windows 10 installation disk for the job.

Format a disk without an operating system

To format a disk without an operating system we will

  1. Create a Windows 10 installation disk.
  2. Set the first boot device.
  3. Boot from the installation disk and access Command Prompt and Diskpart.
  4. Run a set of commands to format the disk.

1. Create installation media

To create a Windows 10 installation media, you need a USB drive that has 8GB storage space. 

  1. Connect the USB drive to the system you will use to create the installation disk.
  2. Visit this link to download the Media Creation Tool from Microsoft. 
  3. Click the Download Tool button.
  4. Run the tool.

  1. Select any version of Windows 10 and choose your USB to burn it to.
  2. Allow the Media Creation tool to create the installation disk.
  3. Remove the USB drive once the disk has been created.

2. Set Boot device

You now need to go to your BIOS and set the first boot device to USB. If you’re BIOS is UEFI, check out this post to learn how to change the first boot device.

3.  Boot from installation disk

You’re now ready to use the Windows 10 installation disk to access Command Prompt and the Diskpart tool

  1. Power your system off.
  2. Connect the Windows 10 installation disk/USB into your system.
  3. Turn the system On and boot from the USB.
  4. Wait until you see the Windows 10 Set Up screen. 
  5. Select a language, time, and keyboard layout, and click Next.
  6. Click the Repair button at the bottom of the next screen.
  7. On the next screen, select Troubleshoot>Command Prompt.
  8. A Command Prompt window will open.
  9. Enter this command to start the Diskpart tool: diskpart.
  10. Tap Enter.

4. Format a disk

The Diskpart tool is now active. You can run the following commands to format the internal drive on the system, or any other drive that’s connected to it.

  1. List all connected disks with this command: list disk.
  2. Note the number that is given to the disk you want to format.
  3. Select the disk you want to format with this command: select disk number (replace ‘number’ with the number assigned to the disk).
  4. Remove all partitions from the disk with this command: clean. This will remove all partitions from the disk.
  5. You can now format the disk using any one of these commands;
    • For FAT32 file system: format fs=fat32
    • For NTFS file system: format fs=NTFS
    • For exFAT file system: format fs=exFAT
  6. Once the format is complete, close the Command Prompt window, and turn your system off.


There are plenty of tools that you can burn to a USB and use them to format a drive. Most of these tools will offer a more refined UI where you don’t need to enter commands to format a disk but they can, in the long run, create problems. That’s why using Diskpart is a better idea. You have to go through the process of creating Windows 10 installation media which is a bit time-consuming but that is the only hard part of the entire process.

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