By Dervish / Last Updated May 4, 2023

Reasons to add unallocated space to D drive

For many computer users, the unallocated space is a very important part. Although you cannot directly write files or folders on it, you still can make full use of it to enlarge another existing partition.

1. D drive is out of space.

Owing to many reasons, such as saving too many files on D drive or software update etc, the D drive may be out of space quickly like C drive. At the same time, you may receive an error message like low disk space. If you want to save more files or folders, you need to solve low disk space warning.

2. The unallocated space does not result in low disk space on another partition.

To fix low disk space, you still can shrink an existing partition to get some space. But the operation will reduce the capacity of the existing partition. Also, the operation may result in low disk space of the existing partition.

In sum, I think the unallocated space is a great choice to solve low disk space error. Because the unallocated space does not belong to any partition.

How to add unallocated space to D drive in Windows 7/8/10/11?

In this part, we will share you with 2 different methods to merge unallocated space to D drive in Windows PC. Choose one based on your situation or requirements.

Method 1. Extend D drive with Disk Management

To add unallocated to D drive via Disk Management, you must pay attention to the following limitations:

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.

Briefly, you can only add unallocated space to the adjacent partition which lies on its left hand. If your disk partition location meets this condition, do as the steps below.

Step 1. Access to the Disk Management window. You can press "Win + R" to open the Run window and type "diskmngt.msc", then Click Disk Management in the Computer Management window.

Step 2. Extend D drive. You can click D drive, select "Extend Partition" to add unallocated space to D drive.

Extend D Drive

Step 3. The "Extend Volume Wizard" pops up and click "Next" button here.

Extend Volume Wizard

Step 4. Click "Next" button and follow all defaulted settings.

Extend Volume Wizard Select Disks

Step 5. Click "Finish" button to finish the process. Now the unallocated space is gone and it has been added to adjacent partition.

Extend Volume Wizard Confirm

However, if it does not meet all above requirements (namely, the unallocated space is not adjacent to D drive), you will find the extend volume is disabled. In this case, a professional partition manager like AOMEI Partition Assistant will be needed. See method 2.

Method 2. Add unallocated space to D drive via AOMEI Partition Assistant

AOMEI Partition Assistant Standard is a professional disk partition management tool which is designed to solve partition and disk problems in Windows 11/10/8/7/XP. With it, you can add unallocated space to any partition effortlessly. It offers you various choices, including Resize Partition and Move Partition, Merge Partition.

Besides, AOMEI Partition Assistant Standard has much more features, including creating hidden partition on USB drive, merging partition without data loss, permanently deleting files from hard drive, Rebuild MBR, etc. Now let’s see how to extend D drive with unallocated space via above mentioned functions.

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Option 1. Resize Partition and Move Partition

Step 1. Install and run AOMEI Partition Assistant Standard on your Windows PC.

Step 2. Enter the main page, right click D partition and select Resize Partition

Resize Partition

Step 3. Drag the D Partition to the left and click OK. Also, you can drag it to the right if there is an unallocated space.

Drag To Extend D Drive

Step 4. Click Apply to start the pending operation.

Apply Add Unallocated Space To D

However, it still not perfect. It requires an adjacent unallocated space (on the right or left side). Besides, here is an easier way. You can merge D drive with any unallocated space as long as it's on the same disk.

Option 2. Merge Partition

Step 1. Enter the main page, right click D partition, choose “Advanced” and select Merge Partition.

Merge Partitions

Step 2. In the Merge Partitions window, select the unallocated space and click OK.

Add Unallocated Space to D Drive

Step 3. Preview the result and click Apply.

Apply Add Unallocated Space to D

Step 4. Click Proceed to start the pending operation.

Proceed Merge Partitions

You can also refer to the steps to add unallocated space to C drive.

Apart from the above methods, you can upgrade to AOMEI Partition Assistant Professional to try other amazing functions to extend d drive or other drives in Windows 11/10/8/7.
1. Extend Partition Wizard: extend your system boot partition without rebooting Windows PC and other partitions
2. Allocate Free Space: directly assign unused space from one partition to another, saving the steps to create unallocated space first.


How to add unallocated space to D drive is not a problem. As long as there is a right adjacent unallocated space to the target partition, you can use Disk Management. If not, you can use free partition manager AOMEI Partition Assistant.

AOMEI Partition Assistant can get rid of the limitation of Disk Management. You just need an unallocated space on the same disk. If the unallocated space at the right side, you can use Extend Partition Wizard. If not, you choose Resize Partition and Move Partition, Merge Partition as you like. If you want to add unallocated space to D drive in Windows Server 2019/2016/2012/2008/2003, you can switch to AOMEI Partition Assistant Server.