By Dervish / Last Updated March 7, 2022

When do you need to reformat disk?

Many users would like to format hard drive for a secondary use, and the situations varies from one to the other. For example, you may want to sell your PC to others. Even though you delete all the personal and sensitive data, you still unsure if it is completely cleaned. Hence, reformatting your hard drive is a must-do event.

Another situation, maybe you just want to clean the hard drive for a fresh Windows installation. You may be interested in one new OS, and want to try it. But there is no spare hard drive at hand, then you could take full advantage of the current hard drive as well as the external hard drive. What you need to do first is wiping hard drive. However, you need to reformat external hard drive or internal SSD/HDD if it was partitioned before. To save important data on the hard drive, please backup disk beforehand.

No matter what motivation you have, the question, how to reformat a hard drive, is much more important now.

Reformatting hard drive issue

Usually, you will think about internal utility, Disk Management in Windows 7 or 10, to do this job. The good news is, yes, you can using Disk Management to format DATA PARTITION. If you want to format a hard drive without OS installation, you can right-click one partition and select Format, and then clickOK. You repeat these steps, until you format all partitions on that drive. However, if you want to format a system partition, the option Format is grayed out.


What’s worth to mention, you do have several options on disk operation, but no Format included, regardless the OS installed or not. Under this circumstance, you need to turn to 3rd party software or other format tool.

Disk Options

Reformat a hard disk drive in two ways:

Reformat a hard drive with AOMEI Partition Assistant

The comprehensive and mighty freeware, AOMEI Partition Assistant Standard, can reformat the hard drive in one time. No matter which disk style, MBR or GPT, your disk is, this software can completely format it. Moreover, you can check error of the disk first to make sure the formation proceed successfully. If you want to do a thorough clean, you can try Wipe Disk after the formation, which will erase all the data on the disk so as to prevent others to use those data by recovering. Download AOMEI Partition Assistant and have a try.

Firstly. Reformat a hard drive with no OS on. Install and launch Partition Assistant. Right-click the hard drive you want to reformat. You can select Delete all Partitions.

Delete All Partitions

Or you can choose Wipe hard drive to completely delete the hard drive.

Step 1. Right-click the hard drive and choose Wipe Hard Drive.

Wipe Hard Drive 16gb

Step 2. Select a wipe method, here we choose Fill sectors with zeros. And click OK. Also, you can upgrade to Professional edition to choose the other 3 methods.

Fit Sectors With Zero 16gb

Step 3. Click Apply to execute the operation.

Apply 16gb

Secondly. Reformat a hard drive with OS on. You need to upgrade AOMEI Partition Assistant to Pro version and run it. Right click Disk 1, and select Delete all Partitions -> Delete all partition or Delete all partitions and wipe all data on the hard drive. Then you will see a pop up window as follow. Click Yes.

Delete All Partitions On System Disk

Way To Delete All Partitions On System Disk

Thirdly. Confirm the virtual result. Click Apply.



This operation will be completed in Windows PE mode. If you want to boot your PC again, you might as well create a bootable media with AOMEI Partition Assistant in advance. Meanwhile, a Quick Partition may be necessary when you want to partition the hard drive.

Easy and fast, the question, how to reformat a hard drive, has been solved completely. With AOMEI Partition Assistant, you can reformat to FAT32 or reformat to NTFS file system as well. In fact, AOMEI Partition Assistant has more powerful features, such as Migrate OS to SSD, Resize/Move Partition, Command Line Partition etc. This software supports all popular Windows OSes as well.

Reformat hard drive using Command Prompt

There is one more method to reformat a hard disk through one of Windows built-in tools, CMD. Command Prompt operations are suitable for advanced Windows user who is familiar with his system. Otherwise, inappropriate commands will lead system unbootable. As a result, use this method with caution. Following will take reformatting an external drive for example.

1. Connect the external disk to your computer and make sure it can be detected by Windows.

2. Press Windows + R key combo to start Run box. Type “diskpart” and hit Enter. If prompted, run as administrator.

3. In Command Prompt, type below commands in order and press Enter to execute after each input.

  • list disk

  • select disk n (n is the number of the external drive you want to format)

  • clean

Clean Disk

Till now, all data on the external hard drive will be deleted. The entire disk will showing as unallocated space in Disk Management. Then type following commands to continue the formatting.

  • select disk n (the same external drive)

  • create partition primary size=122880 (it's MB)

  • format fs=ntfs quick label=backup

  • exit

Format Disk

NTFS is the file system and you can change it to fat32. The “backup” is partition label which can be edited as well. Now, you’ll find the external hard drive has a partition formatted with NTFS and named “backup” in Disk Management. If you want to use it as boot drive, right click the partition and mark it as active.

Mark Partition as Active

Diskpart is a useful partition tool if you’re good at using it. For instance, you cancreate bootable USB drive using Diskpart. Besides, the later partition creation and formatting can be completed in Disk Management as well. You can right-click the unallocated space and select “New Simple Volume”. If the disk shows “Not Initialized” and the “New Simple Volume” grayed out, right click the disk and select “Initialize Disk”. In the pop-up window, select disk type. If the external drive is greater than 2 TB, select GPT. If not, select MBR.