How to Reformat a Hard Drive in Windows 11, 10, 8, 7

How to reformat a hard drive if the drive was partitioned already? AOMEI Partition Assistant will completely wipe all personal and sensitive information, and give a clean disk back.


By Dervish / Updated on May 12, 2023

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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're still unsure if it is completely cleaned. Hence, reformatting hard drive is a must-do event.

Another situation, maybe you just want to clean the hard drive for a fresh Windows installation. 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 an internal utility, Disk Management in Windows 7 or 10, to do this job. The good news is, yes, you can use 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 click OK. 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.


It's worth mentioning that you do have a few options for disk operations, but under some special conditions, Disk Management options will be greyed out. In this case, you need to turn to third-party software or other formatting tools.

Extend Or Shrink Greyed Out

Reformat a hard drive in two ways:

Reformat a hard drive with AOMEI Partition Assistant

AOMEI Partition Assistant Standard, which is a comprehensive and mighty freeware that can reformat the hard drive in one time. No matter the hard drive is MBR or GPT, this software can completely format it. Moreover, you can check error of the disk first to make sure the formation proceed successfully. 

Download Freeware Win 11/10/8.1/8/7/XP
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Situation 1. Reformat a hard drive without OS on

Install and launch it. Right-click the hard drive you want to reformat and select Delete Partition.

Delete All Partitions

Step 1. Or you can choose Wipe hard drive to completely delete the hard drive. 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 turn to Professional Edition to choose the other 3 methods.

Fit Sectors With Zero 16gb

Step 3. Click Apply to execute the operation.

Apply 16gb

Situation 2. Reformat a hard drive with OS on

You need to upgrade to AOMEI Partition Assistant Professional and run it.

Download Demo Win 11/10/8.1/8/7/XP
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Step 1. Right-click the system disk, and select Delete Partition.

Delete All Partitions On System Disk

Step 2. Here, select Delete all partitions or Delete all partitions and wipe all data on the hard drive

Way To Delete All Partitions On System Disk

Step 3. Confirm the virtual result and 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.
▶ 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 OS 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 an advanced Windows user who is familiar with their system. Otherwise, inappropriate commands will lead the 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 Disk

Till now, all data on the external hard drive will be deleted. The entire disk will show as unallocated space in Disk Management. Then type the 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 can create 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.

Dervish · Staff Editor
Dervish is an English editor of AOMEI Technology; He is delicated to offering users easy and effecitve solutions for issuses related to disks and partitoins. In his spare time, he enjoy wathcning films, playing footable, traveling and so on.