By AOMEI / Last Updated June 23, 2021

The disk space which doesn’t belong to any partition is regarded as unallocated space by computer. This refers to no applications are able to write to the space. But it is a logical space on the hard drive so it can be used by putting the system to put files on. In order to make full use of unallocated space, you have to build a new partition with the space or add unallocated space to partitions for extending the size of partition.

Question 1: the hard drive of my computer has two partitions, partition C and partition D. In addition, there is still an unallocated space right behind partition D. I want to install some other programs, but unluckily, there is not enough space in partition C now. Consequently, I decide to add the unallocated space to partition C. How can I realize the goal?

Question 2: I installed my operating system on C drive. With time goes by the data on this drive is getting larger. What’s worse, I am warned by low disk space, when I start my computer. However, I have large unallocated space at the end of this hard drive and there is a small piece of unallocated space about 7.8MB size between two data partitions. Does a way can help me take full of them?

Answer: not only Windows 8 Disk Management, but also third party partition magic tool can aid you in committing the task "add unallocated space Windows 8" easily.

Notes: about the two uses of unallocated space, I want to mention that, it can be added to another partition, but the computer is unable to directly save files in it unless you create partition from unallocated space.


  • With the help of Windows 8 snap-in Disk Management, You can only add unallocated space to adjacent partition to extend the volume.

  • So here you can add the unallocated space to partition D through the following steps.

  • First, right click "computer", select "manage", then select "disk management", and right click partition D.

  • Then, select "Extend Volume" in the pop-up window and you can add the unallocated space to partition D simply.

  • Nevertheless, you can not add the unallocated space to partition C. because the function of "extend volume" can work only if there is an adjacent unallocated space, or the "extend volume" will be grayed out. In other means, you can do that by deleting partition D to get adjacent unallocated space, which is risky of losing data.

In this case, AOMEI Partition Assistant Standard is free all-in-one partition magic softwarefor disk partition which can meet you verified needs such as combine partitions, resize partition, copy partition, bootable CD maker, Windows To Go creator and resolve the problem at ease.

Tips: AOMEI Partition Assistant is also fully compatible with the latest Windows 8.1.

Now, free download the AOMEI Partition Assistant Standard Edition, and solve the problem at once.

Step 1: Launch the software and this is the main interface.

Step 2: You can add unallocated space to partition C by right clicking the C drive, choosing "Merge Partitions" in the pop-up window to accomplish the task.


Step 3: Choose the unallocated space then click ok.


Step 4: Click "Apply" button on the toolbar.


AOMEI Partition Assistant should be the best free partition manager that helps you add unallocated space in Windows 8 easily and safely. It can also allows you to move partition, create partition, and many advanced features. If you upgrade to AOMEI Partition Assistant Professional Edition, you can get more advanced features, such as the function "Allocate Free Space" in dealing with resizing partition of there is no unallocated space. And there is Server Edition for Windows Server users.