Solved: Extend Volume of C Drive is Disabled in Windows 11, 10, 8, 7

In this article, we will explain why the “Extend Volume” of C drive is disabled in Windows 11, 10, 8, 7 Disk Management, and provide corresponding solution to enable this option.


By Emily / Updated on May 12, 2023

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Help! Extend Volume of C drive disabled in Disk Management...


My C drive is almost full and unable to run major applications smoothly. I have some free space on D drive, so I shrunk it to get a piece of unallocated space with about 340GB . However, when i right clicked on C drive "Extend Volume " and try to add unallocated space into C drive, the extend volume of C drive is disabled as shown below.Why this happen? Any one can tell how to fix it? Thanks a lot!

Extend Volume Greyed Out

Why the "Extend Volume" option is disabled in Windows?

It is necessary for users to extend a disk partition when Windows computer says this drive is running out of disk space. This matter a lot if it is the C drive that runs out of space since, because C drive with little space may slow down your computer and even cause other issues, such as system crash or freeze. But when users try to extend C drive space via the Windows snap-in Disk Management tool, some of them find the ‘Extend Volume” is greyed out/disabled (like the above scenario). Generally speaking, the possible reasons can be concluded as following:

There is no unallocated space available on the disk. When there is not any unallocated space on the same disk that contains the partition you wish to extend, the "Extend Volume" will appear to be grayed out.

There is unallocated space, but not adjacent to the target partition on its right side. Disk Management can only extend a volume when it is followed by adjacent unallocated space.

The to-be-extended partition is not formatted with NTFS. Disk Management can only resize (shrink or extend) partitions with NTFS file system.

Confused "Free Space" and "Unallocated Space" that is adjacent to the target volume. This involves the difference between "logical drive" and "primary partition". Logical drives is created or exists inside an extended partition. When we delete a logical drive, we get "Free Space"; while we delete a primary partition and we get "Unallocated Space". To extend a primary partition requires the adjacent “Unallocated Space”, not “Free Space”. So, many users find there is free space adjacent to the target NTFS partition, but the "Extend Volume" is still greyed out.

How to enable the "Extend Volume" option of C drive?

From above, we learn the possible causes behind the "Extend Volume" of C drive greyed out in Windows 11, 10, 8, 7. Now, it is time to find out the corresponding solution.

Solution 1. Get adjacent unallocated space

As for the first and second reason listed above, what we all need to do is to get unallocated space that is adjacent to C drive. To finish such a task in Disk Management, the only solution is to delete the volume that comes right after the C drive. In most cases, it is the D drive that needs to be deleted and then we can get unallocated space on C drive’s right side.

Before you do:✎...
Copy all your data from your D drive or other drive that will be deleted to an external drive or USB to make a backup.

Step 1. Right-click D drive and select "Delete Volume".

Delete Volume

Step 2. After deletion, you will find it becomes unallocated space.

Step 3. Now, you will find the  "Extend Volume" of C drive is enabled and clickable. Follow the wizard and extend C volume.

Extend Volume

You can utilize the unallocated space you need to add into C drive, and then using the remaining unallocated space create a new volume and name it D. Now transfer your data back to the D drive from the external drive.

Solution 2. Convert the file system of C drive to NTFS

Since Disk Management only supports extending NTFS partition, when your C drive is formatted as FAT32, the "Extend Volume" of C drive will be disabled even if there is adjacent unallocated space on its right side. In this situation, you can use DiskPart.exe tool to directly convert FAT32 to NTFS. Different from formatting, the conversion won’t damage any data in the partition.

Step 1.Press Win+R to open Run dialog, input cmd and hit on "Enter".

Step 2. Type in "convert drive_letter: /fs:ntfs". Replace the drive letter with the letter of the drive you’re converting (c, d, or whatever that might be). Finally, press Enter to start the process.

Convert to NTFS

After conversion, you can extend C drive with unallocated space smoothly. You should note that there is no command for converting NTFS back to FAT32.

Solution 3. Delete all logical drives

For this last but not least cause-"Free Space" and "Unallocated Space", it is necessary to delete all logical drives in the extended partition. When it is done, the whole extend partition will turn into unallocated space, then the "Extend Volume" of C drive is enabled and can help extend system volume.

Better tool to extend C drive without limitations in Windows 11, 10, 8, 7

The above content only focuses on how to enable "Extend Volume" of C drive in different situations and then successfully enlarge system partition with unallocated space. It is apparent that extending one volume requires to delete another one and take the risk of data loss. So, here we would like to share you with a better tool to get around “extend volume of C drive disabled” issue completely and avoid data loss risk.

That is to use AOMEI Partition Assistant Standard, a free yet powerful disk partition manager for all editions of Windows 11, 10, 8, 7 and Windows XP/Vista. It makes up the limitations of Disk Management when extending a partition with the below features:

Move Partition: move the partition that is in the way of the partition you plan to extend and the partition located before available unallocated space, namely, switch the locations of middle partitions and unallocated space to make unallocated space and target volume adjacent.
Merge Partitions: directly combine adjacent and non-adjacent unallocated space, no matter where it is in the disk, into the partition you will extend; or merge two adjacent partitions like merging C and D drives.
Both FAT32 and NTFS partitions are supported. The free partition manager can resize FAT32 and NTFS partitions.
Regard “Free Space” and “Unallocated Space” as the same type of usable space. No matter it is the “Free Space” from deleting logical drives or “Unallocated Space” from removing primary partitions, the free partition software allows you to add it into primary partitions via above features.

You can download the freeware and follow the tutorial to learn how the "Merge Partitions" works.

Download FreewareWin 11/10/8.1/8/7/XP
Secure Download

Step 1. Install and run AOMEI Partition Assistant Standard. Right-click C drive, choose “Advanced” and select “Merge Partition”.


Step 2. Tick the unallocated space and click on "OK".


Step 3. Click "Apply" and "Proceed" to commit the pending operation.


See? Only 3 steps can totally save yourself from the issue: extend volume of C drive is disabled in Windows 11, 10, 8, 7. To enjoy much easier and more advanced methods, you can upgrade to Professional that enables you to directly transfer some free space from one partition to another, extend system partition without rebooting PC. Besides, it also supports moving programs from one drive to another one, helping free disk space on the source drive.

Emily · Staff Editor
Emily is an English editor of AOMEI Technology; she has a great passion for providing easy solutions for people to tackle with all disk or partition management problems. In addition to writing articles about disk/partition management, she also edits great tutorials on how to back up and restore disk for data security. In her spare time, she loves to learn computer skill to improve herself or stay with her family to enjoy a good day.