How to Format a Hard Drive with Windows on it Effectively?

Need to format drive with OS on it but have no idea about how to do it? You come to the right place! This tutorial will guide you on how to format a drive drive with Windows on it by introducing two workable ways step by step.


By Hedy / Updated on May 12, 2023

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Reasons for formatting a hard drive with Windows on it

When you use Windows computer, there might be many occasions where you need to format a partition. But if you search the information about the safe way of formatting a hard drive on the Internet, you will find many users are asking "how to format a hard drive with Windows on it". What does it mean?

The hard drive with Windows on it is called system drive or the familiar C drive. In theory, formatting C drive means deleting the operating system, booting files and other OS-related information. It will certainly lead to boot failure. Why do majority of users still want to format drive with OS on it? The main reasons may include:

  • Change a file system. If your file system of system partition is FAT32 that only supports files up to 4GB, you can format it to NTFS file system to get larger size.

  • Reinstall OS. When your Windows operating system is crashed and you can't boot your computer, you can format your C drive and reinstall OS.

  • Fix disk errors. If your disk is infected by viruses or malware and you don't know how to do with it, formatting C drive may be a workable way.

  • ......

Failed to format a hard drive with Windows on it

When you attempt to format a data hard drive, Windows built-in feature like DiskPart, Disk Management, or File Explorer will help a lot. But when you intend to format a system hard drive, these utilities may not work. Here are the real cases:

Case 1. Format option is greyed out in Disk Management

When you open Disk Management and right click C drive, you will find the "Format option is greyed out" in the extended menu. This prevents you from executing the following operations.


Case 2. You can't format this volume in File Explorer

The same as Disk Management, when you open File Explorer and right click the system drive, a pop-out window will warn you that "You cannot format this volume". Your only choice is to to click "OK" and exit the window.


As we can see from the two cases above, you are not allowed to format a hard drive with OS on it when the operating system is running. Both Disk Management and File Explorer will refuse your request to format C drive. This is because Windows will prevent you from executing wrong operations on system drive by mistake.

How do you format a hard drive that has Windows 10 on it?

Although you can't format drive that contains the operating system with Windows built-in tools, there are still ways for you to get it done. In theory, if you boot your computer from another operating system, it will take your original C drive as a data drive, so that you can format it successfully. To make it, there are two methods for you to choose.

▶ Method 1. Use Windows Setup Disc to format drive with OS on it

The first one is to use a Windows installation media (CD, DVD or bootable USB device). You can get it from Microsoft official website. The below steps will show you how to format a system hard drive using Windows Setup Media.

Step 1. Insert Windows installation media into your computer and enter BIOS to boot from it.

Step 2. Select the language and other settings, then click "Next".

Step 3. Click "Install Now" and wait until it finishes.

Step 4. Accept the following terms and conditions and select "Next".

Step 5. Select the Custom (advanced) option.

Step 6. Then, you will move to "Where do you want to install Windows?" window. Click the Drive options (advanced) link under the list of hard drives.

Step 7. Among all the options, select "Format". Now, Windows will start the process of formatting your drive.


▶ Method 2. Use a third-party tool to format drive with OS on it

As described in Method 1, formatting C drive requires Windows installation CD/DVD. However, what should you do if you don't have one? Don't worry, method 2 will save you from the dilemma.

A powerful bootable USB creator named AOMEI Partition Assistant Professional is your best choice. It's compatible with Windows 11/10/8/7/XP and Vista. With this software, you can make a bootable USB, boot your PC from it, and then format a hard drive with Windows on it quickly. Now, download the demo version and have a free trial as the following step-by-step guide:

Free DownloadWin 11/10/8.1/8/7/XP
Secure Download
Prepare a USB device that has at least 8GB in size to create a bootable media.
All the data on the USB will be erased, please back up the important files in advance.

Part 1. Make a bootable media

Step 1. Connect your prepared USB to your computer and make sure it's well-detected.

Step 2. Install and run AOMEI Partition Assistant on your computer. In the main interface, click "Make Bootable Media".


Step 3. In the pop-up window, choose "USB Boot Device" and click "Proceed".


Step 4. A pop-out message says that all the data on the USB drive will be formatted, click "Yes" to start the operation. After a while, the bootable USB will be created successfully.

Note: If you create the bootable media on another computer, remember to unplug it and insert it into your computer. Then follow the next steps.

Part 2. Boot computer from the bootable media

Step 5. Restart the computer and enter BIOS to change boot order, and make sure your computer will boot from the USB device.

Note: The way to get into BIOS varies from computer to computer. The most common BIOS key could be F10, F2, F12, F1, or DEL.


Part 3. Format a hard drive with Windows on it securely

Step 6. Once you boot from the bootable USB successfully, you will be in the main console of AOMEI Partition Assistant automatically. On the main interface, right-click the C partition and select "Format Partition".


Step 7. In the pop-out mini window, you can select a proper file system for your needs and click "OK".


Step 8. Hit on "Apply" and "Proceed" to commit the pending operation.



Don't know how to format a hard drive with Windows on it? This passage has taught you two reliable and workable ways to get it done quickly. The operation which is not allowed in Windows could be realized by AOMEI Partition Assistant safely and easily.

As a promising alternative to Disk Management, you can use AOMEI software to resize/move partition, create partition, delete partition, wipe partition, etc. Besides, there are many other fantastic functions you can use to optimize your hard drive like migrating OS to SSD, deleting large files, moving folders from C drive to D drive, and so on.

Hedy · Staff Editor
Hedy is an editor of AOMEI Technology. She is very good at solving problems of partition management, and she wants to share all the problems she had already solved to users who met the same questions.