Solution - Cannot Extend C Drive Partition in Windows 11

by John, Updated on: October 14, 2021

C drive low disk space is common issue in Windows 11 and previous version computer. Nobody likes to recreate partitions, reinstall operating system and programs. It also costs a long time if you back up everything, recreate partitions and restore. The same with Windows 7 and Windows 10, there's "Extend Volume" function in Windows 11 Disk Management. It is able to extend system partition and data volume if there's contiguous Unallocated space. Some people try to increase C drive space in Disk Management but failed, because Extend Volume is grayed out. In this article, I'll explain why you cannot extend C drive in Windows 11 with Disk Management and what to do if you are unable to extend C drive partition in Windows 11 laptop, desktop or tablet computer.

Why cannot extend C drive in Windows 11 Disk Management:

Reason 1: no adjacent Unallocated space

Firstly, you should know that there must be Unallocated space on the same disk before extending a partition. On a physical hard disk or some types of hardware RAID array, you can get Unallocated space by shrinking or deleting another volume. On a virtual machine disk or some types of hardware RAID array, you can expand disk to get extra Unallocated space.

In most of Windows 11 computers, the system disk is SSD (Solid State Drive). Of course there is still traditional mechanical disk. But no matter which type the disk is, a 500GB physical hard disk can't be decreased to 400GB or increased to 600GB. Before extending C drive, you must delete or shrink another volume to get Unallocated space.

With Disk Management Shrink Volume function, you can shrink NTFS partition without losing data (not 100%). The problem is, Disk Management can only make Unallocated space on the right when shrinking volume.

For example, after you shrinking D: drive via Disk Management, Unallocated space is on the right of D drive. To extend C drive in Windows 11 Disk Management, there must be adjacent Unallocated space on the right of C drive. This is the reason why you cannot extend C drive in Windows 11 after shrinking D drive or any other partition.

Reason 2: the adjacent partition is Logical

In most of Windows 11 laptop or desktop, the system disk is GPT style. Few people will encounter this issue but it is still one of the reasons why you are unable to extend C drive in Windows 11 Disk Management. Because Extend Volume is disabled to C drive after shrinking D, some people try to delete D drive.

Note: I just want to explain the reason, I'm not telling you to delete partition. This operation is not suggested.

Extend Volume will be enabled to C after deleting D if D is Primary partition. Otherwise, you still cannot extend C drive in Windows 11 with Disk Management. Because unlike independent Primary partition, Logical drive is just part of the Extended partition. After deleting a Logical drive, its disk space is shown as Free instead of Unallocated. This Free space can't be extended to any Primary partition even if it is contiguous and on the right.

What to do if unable to extend C drive partition in Windows 11:

Solution 1: move partition and Unallocated space

If you've shrunk D drive (or other adjacent volume), but cannot extend C drive with nonadjacent Unallocated space. In this case, move D drive rightwards and move Unallocated space leftwards. When Unallocated space is contiguous, C drive can be extended easily. To move partition and Unallocated space, you need third party software, because no Windows native tool has this ability. There's free disk partition software for Windows 11/10/8/7/Vista/XP home computer users.

Download NIUBI Partition Editor free edition, you'll see all disks with partition layout and other information on the main window. In my computer, there's 30GB Unallocated space which is shrunk from D: drive.

NIUBI Partition Editor

Follow the steps when you cannot extend C drive in Windows 11 laptop/desktop/tablet:

  1. Right click D: drive and select "Resize/Move Volume" option, drag the middle block towards right in the pop-up window. Then D drive will be moved to the right and Unallocated space will be moved to the left side.
    Move D drive
  2. Right click C: drive and select "Resize/Move Volume" option again, drag the right border towards right to combine this adjacent Unallocated space.
  3. Click Apply on top left to take effect, done.

Watch the video how to operate:

Windows 11

Solution 2: recreate partition and shrink

If you've deleted the adjacent Logical partition but can't extend C drive volume in Windows 11 Disk Management, follow the steps below:

  1. Right click this free space in Disk Management and select Create Volume option.
  2. Right click the new created partition in NIUBI Partition Editor and select "Resize/Move Volume", drag the left border towards right to shrink this partition and make Unallocated space on the left. If you don't want to keep this partition, right click it and select Delete Volume option.
  3. Follow step 2 above to add Unallocated space to C drive.

Besides shrinking, moving and extending partition in Windows 11/10/8/7/Vista/XP computer, NIUBI Partition Editor helps you do many other disk partition management operations such as merge, convert, defrag, hide, wipe, scan bad sectors, optimize file system, etc.