How to Add Unallocated Space to C Drive in Windows 10/11

Want to move unallocated disk space to C drive in Windows 10? This page introduces you a step-by-step guide about how to extend C drive with unallocated space.

Can I add unallocated space to the C Drive in Windows 10/11? Sure! In this post, EaseUS Software offers three tools for this purpose. 

Is there a way to put this unallocated space on the C: Drive?
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Can't extend the C drive since the Extend Volume option is greyed out? No worry! This post is the right place for you. Disk Management can only extend the C drive when the unallocated space is exactly behind it. Or you will encounter the Extend Volume greyed-out error in Disk Management. Luckily, we offer three ways to merge C drive with unallocated space. Check the table below and select a suitable tool based on your needs:

So, first of all, open Disk Management to check if the unallocated space is on the right side of the C drive.

• As the picture shows, Disk Management and Diskpart can only work when the unallocated space is on the right side (adjacent) to the target partition.

For other situations, you need to use third-party software such as EaseUS Partition Master.

It can directly merge C drive with nonadjacent unallocated space. If there is no unallocated space, it can help merge C drive with another partition with free space. Check the detailed features of this disk partition manager software:

Compatibility: Works on Windows 11/10/8/7

Key features to help with C drive low disk space error:

• Merge or extend C drive with adjacent or nonadjacent unallocated space
• Merge C drive with another drive
• Allocate more space to C drive
• Move/resize partitions without limitations

Storage Devices Supported: SD card, USB flash drive, external hard drive, SSD, HDD, etc.

Now, based on your case, follow the correct guide to begin allocating more space to the C drive.

• Way 1. Use EaseUS Partition Master
• Way 2. Use Disk Management
• Way 3. Diskpart

How to Add Unallocated Space to C Drive

This part covers three guides on how to add unallocated space to the C drive on Windows 10/11. If the unallocated space is adjacently on the right side of the C drive, you can feel free to merge or extend the C drive with diskpart or Disk Management. In other cases, use EaseUS Partition Master. 

Way 1. Use EaseUS Partition Master

Compared with Windows built-in tools, EaseUS Partition Master is easier to use and offers more functions. It can merge C drive with nonadjacent unallocated space and extend C drive with adjacent unallocated space. Follow the two guides below to add more space to the C drive.

Guide 1. Add Nonadjacent Unallocated Space to C Drive

Here is how to merge nonadjacent unallocated space to the C drive on Windows 10/11:

Step 1. Launch EaseUS Partition Master and navigate to the "Partition Manager" section.

Step 2. Right-click the C drive and select "Merge" and select the nonadjacent unallocated space; select C in the "Merge this partition to" box.

Step 3. Click "OK" to continue and click "Execute the task" to begin. Then, you can see the nonadjacent unallocated space is merged into the C drive.

Guide 2. Add Adjacent Unallocated Space to C Drive

It's easier to allocate more space to the C drive if there is unallocated space adjacent to the C drive. Here is how:

Step 1. Launch EaseUS Partition Master and go to the "Partition Manager" part.

Step 2. Right-click the C drive and select "Resize/Move". In the new window, drag the icon circled in green to decide how much space you want to allocate to the C drive.

Step 3. Click "OK" to continue and click "Execute the task" to begin. Then, the C drive will be bigger and have more free space.

Do not forget to share this post and let more users learn how to add unallocated space to the C drive.

Well, if you have 2 or more disks on your PC, you can use EaseUS Partition Master to extend C drive with another disk. Check the link to get more:

Video Tutorial - How to Move Unallocated Space to C Drive on Windows 11/10/8/7

Before reading the tutorial, you can watch the video and start with 1:11 to learn how to add unallocated space to extend c drive.

Apart from extending C drive with unallocated space on Windows 10, Windows 11 users can also apply this partition manager software - EaseUS Partition Master to extend c drive in Windows 11 on their own like an expert.

Way 2. Use Disk Management

How to format the existing unallocated space on the C drive in Windows 10/11? You can use Disk Management tool. 

Open Disk Management through the Run window by pressing the Windows icon + R at the same time, then enter 'diskmgmt. msc' and click 'OK'. 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.

Way 3. Diskpart

Diskpart is an ideal option for advanced users since it's efficient. However, it lacks a graphical interface. You can only extend the target partition by accurately typing the right commands. But don't worry; we will show you how to add unallocated space in Windows 10/11 to the C drive via DiskPart.

Step 1. Search Diskpart in the search box and select "Open."

Step 2. Type the following commands, and after each, click Enter to confirm your action:

• list disk
• select disk 0 (Replace 0 with the correct disk number)
• list volume
• select volume 0 (Replace 0 with the volume number of your C drive.
• extend size=1024 (replace the number (MB) with the disk space you want to add to the C drive; make sure the number is no more than the unallocated space)

Can't add unallocated space to the C drive? Turn to EaseUS Partition Master.

Conclusion

C drive often faces out-of-space errors. We have shared with you three ways to help you move unallocated space to C drive in Windows 11, 10, 8, and 7. You can choose one that suits your specific situation. Hope we can help.

FAQs About Allocating More Space to C Drive

Why can't I add the unallocated space to the C drive? Why is the Extend Volume option greyed out in Disk Management? Check the following questions and answers.

1. Why can't I extend C drive with unallocated space on Windows 10?

The most common issue is that the unallocated space is not adjacent to the C drive. Disk Management can only extend C drive when the unallocated space is directly to the right of it. 

2. How to add unallocated space to the C drive on Windows 10?

Here is how:

Step 1. Right-click the Windows icon and select "Disk Management" from the list.

Step 2. Right-click the C drive and select "Extend Volume."

Step 3. Follow the Extend Volume Wizard to select how much space (in MB) you want to extend. Type the number you want or just leave it as default. After this, click "Finish" to complete the action.

3. Why is the Extend Volume grey in Disk Management?

The "Extend Volume" option in Windows Disk Management is greyed out for several reasons:

1. No Contiguous Unallocated Space: The most common reason is that there is no unallocated space directly adjacent to the right of the volume you want to extend. Windows requires contiguous unallocated space to enable the "Extend Volume" option.
2. Partition Format: The "Extend Volume" option only works with NTFS or RAW partitions. If your partition is formatted as FAT or another file system, this option will be unavailable.
3. Partition Type and Layout: If it's a primary partition within an extended partition or it's a recovery partition, you can't extend it.
4. MBR Disk Limitations: If you are using an MBR disk and the partition has reached the 2TB limit, you cannot extend it further without converting to a GPT disk.