By Cherry / Last Updated April 21, 2020

Unable to extend partition with unallocated space

When partitions are not divided properly, you may encounter a problem that some partitions are running out of space, as time goes by. This will influence the computer performance. Especially when C drive is full of applications and data, the running speed of your machine will reduce significantly. Then, you will need to extend the small volume or even to upgrade to larger disk if the capacity of your existing hard disk is too small.

If there is unallocated space available on the hard drive, you can extend the volume by adding into the allocated space using the “Extend Volume” feature of Windows 10, 8, 7 built-in Disk Management tool. Just open the Disk Management, right-click the partition which you want to extend, and then select the "Extend Volume" in the drop-menu. Unfortunately, you may find that the Extend Volume grayed out and you can't extend volume to unallocated space as expected.

Why cannot extend volume to unallocated space?

Many users may meet the problem that Extend Volume grayed out. 5 situations are concluded as follows:

1. "I have unallocated space at the end of the hard drive, and I want to extend my system partition with it. However, when I try to use "Extend Volume" function of Disk Management tool to add the unallocated space to the system partition, I found it is grayed out."

Grayed Option

You should know the “Extend Volume” function only works when the unallocated space is in the adjacent right side of the to-be-extended volume. Otherwise, the “Extend Volume” will be disabled.

2. "I have unallocated space, but I cannot extend the volume to the blank space. The basic environment of my hard drive is liking the screenshot. I want to extend my E: drive with the unallocated space behind it, but the Extend Volume is grayed out".

Extend Volume Grayed Out

Although there is unallocated space at the right side and adjacent to the E: drive, the Extend Volume option is still gray. Why? That's because both the partitions C: and E: are logical drives contained in an extended partition, which cannot be extended. As a workaround, you have to delete the logical partition first, then delete the extended partition, so that you can create logical partitions again.

3. If the unallocated space is at the left of the target partition, you cannot use Disk Management to extend volume with it too.

4. Disk Management cannot extend volume to unallocated space if the target primary volume is formatted with FAT32. The Extend Volume only supports NTFS and RAW partition.

5. The Extend Volume function built-in Disk Management tool since Windows 7. Before Windows Vista, there is no function to extend volume in Disk Management.

Easily extend volume to unallocated space with free partition software

When Disk Management cannot extend volume to unallocated space, you can switch to a free partition manager named AOMEI Partition Assistant Standard. You can use it to extend either NTFS or FAT32 volume in all versions of Windows 10/8/7, and Windows Vista/XP (32-bit and 64-bit). It also has Server Edition (paid) specifically for Windows Server OS, including Windows Server 2019/2016/2008/2006/2003/2000.

Much better and more powerful than Windows Disk Management, it is able to move partition to make unallocated space contiguous to the volume you wish to extend, so that you can extend it using the “Extend Volume” feature. Besides, it comes with the “Merge Partitions” function, allowing you to merge adjacent or non-adjacent unallocated space into the target volume within 3 steps. The latter is much easier and time-saving. You can free download the software and give it a try.

Step 1. Install and run AOMEI Partition Assistant Standard. Right-click the partition you want to extend and select "Merge Partitions" at the drop-down menu.


Step 2. Then, tick the box before the unallocated space.


Step 3. After that, click "Apply" to execute it.


Besides, its “Resize Partition” feature can extend volume to the adjacent unallocated space no matter it is at the right side or left side. Just right-click the target volume, select “Resize Partition”, drag the edge towards the blank space to extend the volume. After that, click Apply to submit the operations.

Resize Partition

Last but not least, if there is no unallocated space, you can upgrade to Professional edition, which has the “Allocate Free Space” feature to directly transfer space from one volume to another volume (like from D to C) without damaging the data.

Allocate From D To C


See? AOMEI Partition Assistant software provides more than one sure-fire solutions to “cannot extend volume to unallocated space in Disk Management” problem. Additionally, you can also use the Extend Partition Wizard to extend the non-system and system partition without rebooting computer. What’s more, it is featured with many other useful functions like making conversion between NTFS and FAT32 without formatting, converting GPT to MBR or MBR to GPT without deleting partitions, wiping hard drive and so on.