By Ivy / Last Updated July 24, 2020

Need to Add Unallocated Space to D Drive

If you get used to storing personal files, programs, or software update etc on the D drive, it will be easy and quick to run out of space. Thus, we need to add some unallocated disk space to it. The unallocated space is a very important part of disk partitioning. Although you cannot directly write files or folders etc on it, you can add it to another existing partition to increase the storage space. Of course, we can shrink or delete an existing partition to get such space.

Add Unallocated Space to D Drive using Disk Management

Similarly to C drive, D partition may be full for some reason. So how to add unallocated space to D drive? To achieve that, we can use the “Extend Volume” option in Disk Management, which can help extend one partition with an adjacent unallocated space on the right side. Therefore, before merging unallocated space into D drive, we have to make sure:

1. There must be one or more unallocated space .

2. The unallocated space must be adjacent to the target partition.

3. The unallocated space must be at the right of the target partition.

When all conditions are here, take the following steps, please:

Step 1. Click Start, then right-click Computer and select Manage or you can use “Win + R” to open Run window and type “diskmngt.msc”.

Step 2. Click Disk Management in the Computer Management window, then you will see all the disks and corresponding volumes


Step 3. Click D volume, select Extend Partition and specify the space you want to add to D volume in the next window.

Extend Volume

Step 4. Wait for a few minutes, you can get the result. The disk space of D drive increases from 16.32 GB to 17.84 GB.

New Size

Unable to Add Unallocated Space to D Drive

However, if it does not meet all the above requirements, you will be unable to add unallocated space to D drive via the “Extend Volume” option. That is to say, when the unallocated space is not adjacent to the target partition, you will see the “Extend Volume” greyed out (shown as the picture below). In this case, you might wonder if it is possible to move a partition to make the unallocated space next to the D drive. Unfortunately, Disk Management does not support moving partition.

Unable Extend D

Add unallocated space to D Drive with 3rd Freeware

Since Windows built-in Disk Management cannot add non-adjacent unallocated space into D drive and not support moving partition, it is necessary to apply a more professional partition manager. Here we recommend you using AOMEI Partition Assistant Standard.

Much advanced than Disk Management, its “Resize Partition” function can add the adjacent unallocated space on the its both right and left side to the aim partition. Besides, it is able to move partition to make unallocated space next to the aim partition. Moreover, it comes with “Merge Partitions”, which allows you to merge unallocated space, no matter where it is on the disk, to another partition within 3 steps. Here we mainly show how to make use of the “Merge Partitions” feature.

Step 1. Download, install and run AOMEI Partition Assistant Standard. Right click D drive and select “Merge Partitions”.

Merge Partitions

Step 2. Tick the unallocated space and click on “OK”.

Tick Unallocated Space

Step 3. Click “Apply” to commit the pending operation.


AOMEI Partition Assistant is designed to solve partition and disk problems for Windows users, such as Windows 7/8/10/XP etc. It has much more functions, resize partition, create hidden partition on USB drive, clone partition, clone hard disk, convert non-system disk between MBR and GPT without losing data, rebuild MBR etc.


Up to now, how to add unallocated space to D drive in Windows 7/8/10 is not a problem anymore. In this article, we mainly introduce two ways to extend D drive with unallocated space. You can choose any of them based on your situation. Obviously, AOMEI Partition Assistant Standard is worth a try.

If you upgrade to Professional, you can enjoy more advanced functions: transfer OS from MBR disk to GPT, convert system disk to MBR or GPT without deleting partitions, recover lost partitions, extend NTFS system drive without rebooting and more.