By Emily / Last Updated March 10, 2022

Why need to wipe unallocated space?

Why you might need to wipe unallocated disk space? The first and foremost one should be deleting data from this space to prevent sensitive data from leakage.

When you delete the partition, you cannot clear up the data on the unallocated space completely. That’s due to how the file systems like NTFS, FAT32 works. The files that are removed by deleting partition within Windows are not immediately deleted, and they are simply marked as “deleted” from the Master File Table (the index of hard drive). So these deleted files just become inaccessible from within Windows.

This just makes the deleted data a little harder to access, and anyone using data recovery tools can recover those files easily. Therefore, it is necessary to permanently wipe unallocated space.

2 Methods to wipe unallocated space in Windows 10/8/7

In this part, we will provide you with 2 different methods to wipe data from unallocated space on Windows computer. Take a look at them and choose one based on your requirements.

Method 1. Erase unallocated disk space with Cipher.exe

Cipher.exe is a built-in tool in Windows XP and later versions of Windows PC. It was originally developed to encrypt/decrypt files, but it also has a “wipe” option that securely removes the files that you have already deleted.

The “/w” option which stands for Wipe. When you run it, it overwrites all of the unused/unallocated space on your hard drive (or a specific folder) three times – three passes. The first pass replaces all of your deleted file information with one’s, the second pass with zeros, and the third pass with random numbers. To wipe disk unallocated space with Cipher.exe, follow the steps:

Step 1. Press "Win+R" to open "Run" dialogue. Input “diskmgmt.msc ”and tap OK to open Disk Management.

Step 2. Right-click on the unallocated space and choose "New Simple Volume". Follow the guide to create a new partition with a drive letter on the unallocated space.

Step 3. Open Command Prompt window: press Win+R to open Run dialogue. Input “cmd ”and tap OK.

Step 4. Type “cipher /w: ” and press Enter.

Wipe Unallocated Space

How much time it will cost mainly depends on how large the unallocated space is because it needs to read and overwrite every sector on your drive – three times.

Method 2. Wipe unallocated space with a free partition manager

To erase unallocated space on Windows PC, you can also resort to a free partition manager called AOMEI Partition Assistant Standard. This freeware can not only wipe the entire disk, wipe a specific partition, but also wipe data on unallocated disk space in Windows 10/8/7 and Windows XP/Vista (32bit and 64bit). You can click the button, free download it, and install AOMEI Partition Assistant Standard.

Download Freeware Win 10/8.1/8/7/XP
Secure Download

Step 1. Run AOMEI Partition Assistant Standard. Click the unallocated space, choose “Wipe Data” on the left side.

Wipe Unallocated Space

Step 2. In the mini window, choose “Fill Sectors with Zero” and click “OK”.

Select Wipe Method

✎Note: to choose another three advanced wiping methods ( Fill sectors with random data, DoD5220.22-M, Gutmann), please upgrade to AOMEI Partition Assistant Professional.

Step 3. Back to the main interface, click “Apply” to commit the pending operation.


This method can also apply to wipe free space on hard drives. In addition to the data wiping function, AOMEI Partition Assistant Standard also has the following amazing functions:

Convert non-system disk between MBR and GPT partition styles without deleting partitions;

Migrate OS between MBR and MBR disk (HDD/SSD).

Merge unallocated space and adjacent partitions;

Copy partition to another hard drive;

Rebuild MBR (Master Boot Record) on HDD or SSD drive.

Final words

So, when you need to wipe unallocated space, there are two methods available. Apparently, the GUI tool-AOMEI Partition Assistant Standard is a better choice. Moreover, its Professional edition can erase Solid State Drive from all most popular brands such as Samsung, SanDisk and more. To erase data from unallocated space or free space in Windows Server 2019/2016/2012/2008/2003,you can try AOMEI Partition Assistant Server.