How to format a disk without an operating system

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

A tool that can run from the bootloader is required to access and format a disk from outside of an operating system. There are a few options, however we recommend utilizing a Windows 10 installation CD for this task.

Format a disk without an operating system

We’ll format a disk without an operating system if we don’t have one.

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

1. Create installation media

A USB device with 8GB of storage space is required to build Windows 10 installation discs.

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

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

2. Set Boot device

Now go into your BIOS and change the first boot device to USB. If your BIOS is UEFI, follow the instructions in this page to change the initial boot device.

3. Boot from installation disk

You can now access Command Prompt and the Diskpart utility using the Windows 10 installation disk.

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

4. Format a disk

Now you may use the Diskpart utility. The following commands will format the system’s internal disk, as well as any additional drives linked to it.

List all connected disks with this command: list disk.
Note the number that is given to the disk you want to format.
Select the disk you want to format with this command: select disk number (replace ‘number’ with the number assigned to the disk).
Remove all partitions from the disk with this command: clean. This will remove all partitions from the disk.
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
Once the format is complete, close the Command Prompt window, and turn your system off.

Conclusion

There are numerous tools that may be burned to a USB drive and used to format a drive. Most of these tools will have a more polished user interface that eliminates the need to type commands to format a disk, but they may cause problems in the long run. As a result, utilizing Diskpart is a superior option. You must go through the process of producing Windows 10 installation media, which takes some time but is the only difficult portion of the procedure.