[3 Methods] Move Unallocated Space to the C drive in Windows 11, 10, 8, 7

💡 Question	Why need to move unallocated space to C drive in Windows 10?
🔨Solutions	Tool 1. Windows Disk Management Tool 2. Windows Diskpart Tool 3. Third-party disk manager
✨FAQs
📌Summary

Why need to move unallocated space to C drive in Windows 10?

Unallocated space is blank disk space and does not belong to any partition, with which users can create a new volume or extend another partition. In most cases, users may want to move unallocated space to C drive Windows 10 for the following reasons:

• Increased Storage Capacity That's mainly because the C drive is the partition where the operating system is installed, and C drive provides more space for storing files, applications, and system data by default. Extending  C drive helps prevent low disk space warning and allows for the installation of new software without worrying about insufficient disk space.

• Enhanced System Stability A full C drive can lead to system instability and errors, as Windows may struggle to write temporary files or perform system updates. And your PC will get slower and slower, even frozen during other tasks. Extending the C drive reduces the risk of encountering these issues and helps maintain system stability.

• Easier Backup Process With more space on the C drive, you can create more comprehensive backups of your system and data, ensuring that your important files are safely stored and easily recoverable in case of system failure or data loss.

3 Ways to move unallocated space to C drive in Windows PC

From above, allocating the unallocated space to the C drive and making it larger is of great necessity. Here we provide you with 3 different methods to extend the C drive in Windows 10 with unallocated space (also works for Windows 11, 8, and 7).

	Easy operation	Graphical interface	Safe process	Multiple functions	Suitable for novices
Disk Management	✔	✔	✔	✘	✔
DiskPart	✘	✘	✘	✘	✘
AOMEI Partition Assistant	✔	✔	✔	✔	✔

Method 1. Use Windows Disk Management to add unallocated space to C drive

Microsoft has kept the Windows Disk Management tool in Windows 10/11 which users can use to perform many operations. In Disk Management, you can resize partitions, convert MBR to GPT, move unallocated space to C drive Windows 10, and more.

Step 1. Press the Windows key + R at the same time to open Disk Management through the Run window.

Step 2. Enter ‘diskmgmt.msc’ and click ‘OK’.

Step 3. Once Disk Management has loaded, right-click on the C drive, and select the "Extend Volume" option to extend the C drive with the unallocated space.

However, some users find the "Extend Volume" greyed out and the process cannot go smoothly.

For example, when you can get unallocated space by shrinking D drive with Disk Management, but when you try to allocate unallocated space into the C drive, you'll encounter the mentioned problem. That's because the unallocated space is not adjacent to the C drive, or the unallocated space is not on the righthand side. The Disk Management can only extend a partition with an adjacent unallocated space on its right side. 

Fortunately, there are two other ways for you to move unallocated space to C drive.

Method 2. Use Windows DiskPart to extend C drive

As a command-line tool, Diskpart is preferred by advanced users because it lacks a graphical interface. Only when you type the right commands accurately can you extend the target partition. But don't worry, we'll show you how to extend the C drive in Windows 10 with unallocated space via DiskPart.

Note: The same as Disk Management, DiskPart only works when there is adjacent unallocated space behind the C drive.

Step 1. Press “WIN+R”, type “diskpart” and hit "Enter" to open it.

Step 2. At the Diskpart prompt, type the following commands one after one and press Enter.

● list disk

● select disk 0 (0 is the disk where the partition is located)

● list partition

● select partition 4 (4 is the target partition)

● extend size=100 (100 is the size in MB of the partition you want to extend)

Then, it will remind you that Diskpart extended the partition successfully.

Method 3. Choose AOMEI Partition Assistant to move unallocated space to C drive

The good news is that if Disk Management or DiskPart doesn’t work for you since the unallocated space and the C drive are not adjacent, you can turn to AOMEI Partition Assistant Professional Edition. This perfect specialist partition manager provides different functions to make you move unallocated space to C drive in Windows 10, 11, 8, and 7. 

Compared with the above two Windows built-in tools, AOMEI Partition Assistant Professional has more advantages:

✔ Its graphical interface and detailed instruction make it easy for everyone to operate. ✔ It perfectly solves the problem of no connection between the C drive and the unallocated space. ✔ It can move and resize partitions without limitations. ✔ It allows you to move programs, delete files, clone disks, and more.

You can download the demo version and have a try first of all.

Option 1. Move unallocated space next to C drive and enlarge it

In AOMIE Partition Assistant Professional, there is a function called "Move Partition", which can help move unallocated space next to C drive and then combine them into one. Only in several simple steps, you can add unallocated space to the C drive.

Step 1. Install and launch AOMEI Partition Assistant. You will now be able to see that the unallocated space is not adjacent to your C drive (which prevented you from using Disk Management). Right-click on the D drive and select ‘Resize/Move Partition’ from the menu.

Step 2. In the window, you should drag the D drive towards the righthand side as shown in the illustration below, and click OK. This will allow you to move the unallocated space to the C drive.

Step 3. You will now find that the unallocated space is adjacent to the C drive. Next, you can right-click the C drive and select ‘Resize/Move Partition’ to add the unallocated space to your system partition.

Step 4. In the window, you should drag the C drive towards the righthand side to increase the drive size with the unallocated space. Next, click OK and you will return to the main window.

Step 5. Finally, click Apply in the window's top left-hand corner to submit the pending operations.

Note:✎...

If the unallocated space is on the left-hand side of the C drive, you can also use the Resize Partition function to add the unallocated space to the C drive.

Option 2. Directly merge the unallocated space to the C drive

If you think the above option is a bit complicated, then you may prefer this method as it uses a simpler process to move the unallocated space to the C drive.

Step 1.  Install and launch AOMEI Partition Assistant. Next, right-click on the C drive, click Advanced, and select ‘Merge Partitions’ from the menu.

Step 2.  In the popup window, you should select the partitions you want to merge and click OK. This will allow you to merge the partitions directly with the C drive without having to worry about where the unallocated space is located.

Step 3. Back in the main window, you will be able to preview the new C drive size. You will need to click on Apply in order to complete the merger of the partitions.

FAQs about moving unallocated space to  C drive Windows 10

◆ How do I transfer unallocated space to C drive? If the unallocated space is right behind C drive, you can directly extend C drive with it. But if it's not, then you can use AOMEI Partition Assistant to merge that unallocated space to C drive.

◆ How to merge unallocated space to C drive which is not adjacent? If the unallocated space is not adjacent to your C drive, then you'd better choose AOMEI Partition Assistant to merge that space into your C drive. You can't move partition space in Disk Management and Diskpart.

◆ How to move unallocated space next to C drive? You can use a third-party disk manager like AOMEI Partition Assistant Professional. It can help move the unallocated space next to the C drive effortlessly. The detailed steps are shown above. After that, you can easily enlarge the C drive with the unallocated space. 

◆ Why disk C cannot extend volume? If you are using Windows inbuilt utilities, Disk Management or DiskPart, the inability to extend the C drive is because there is no contiguous unallocated space behind the drive C. You can move the unallocated space to be adjacent to the C drive and then extend the volume or directly merge the unallocated space to the C drive.

Summary

In this article, we share you with 3 methods to help move unallocated space to C drive in Windows 11, 10, 8, and 7. You can choose one according to your specific situation. Apart from the above functions, AOMEI Partition Assistant also comes with many other amazing features such as moving applications from one drive to another (it can help free up drive space), migrating OS to SSD/HDD, converting MBR and GPT without losing data, test SSD or HDD speed, etc. 

If you are using the Windows Server 2025/2022/2019/2016/2012 system, you can turn to AOMEI Partition Assistant Server.