Unable to extend C

Cannot/unable to extend C drive in Windows 10

Microsoft adds new Shrink Volume and Extend Volume functionalities in Windows Vista Disk Management, which can be used to decrease and increase size of partitioned drives. Windows 10 inherited these functionalities, so you can shrink and extend partition with Windows native Disk Management. However, these functionalities are very limited. Search by Google or in technical forums, you may find similar problem that many people are unable to extend C: drive in Windows 10 Disk Management with the built-in tools.

In this article, I’ll explain why you cannot extend C drive in Windows 10 Disk Management and how to solve this problem easily with professional partition software.

Unable to extend C

Why cannot extend C drive in Windows 10 DM?

In a word: to enlarge a drive with Extend Volume, there must be adjacent Unallocated space on the right side, otherwise, Extend Volume is greyed out.

No adjacent space

From the screenshot above, there is no adjacent Unallocated space behind, of course you are unable to extend C drive.

Besides Extend Volume, there is Shrink Volume in Windows 10 Disk Management, so many people want to expand C drive by shrinking D. But Extend Volume is disabled for C drive after shrinking D. This is the most common situation that people feedback unable to extend C drive in Windows 10.

Unable to extend C

From the screenshot above, the Unallocated space that shrank from D is not adjacent to drive C, so you still cannot extend C drive.

In fact, there are other reasons that could cause Extend Volume grayed out, for example:

  • Extend Volume only supports NTFS and RAW partition, FAT32 and other types of partitions cannot be extended.
  • In MBR disk, Extend Volume is disabled for a Logical partition even if there is adjacent Unallocated space on the right side. Meanwhile, adjacent Free space in Extended partition cannot be added to a Primary partition.

Few people use FAT32 for system C drive, and Windows 10 use GPT disk by default, so few people will encounter the problem that caused by the reasons above.

Windows 10 unable to extend C drive solution

Actually, it is very easy to solve this problem. You just need 1 step to run NIUBI Partition Editor to move the Unallocated space behind C drive, and then Extend Volume will be enabled.

Download NIUBI Partition Editor, the right side of the main interface is very similar with Disk Management.

Main interface

As you see, there is 20GB Unallocated space behind drive D, let’s see how to move it to behind C drive.

Right click drive D and select Resize/Move Volume, drag the middle position towards the right.

Move D

Drive D is moved to the right and Unallocated space is moved to the left at the same time.

Unallocated space moved

Click Apply on top left to execute this operation. Extend Volume will be enabled for C drive in Disk Management after NIUBI complete.

In this situation, to extend C drive in Windows 10, you just need 1 step with NIUBI. Right click C drive and select Resize/Move Volume again, in the pop-up window, drag the right border rightwards.

Extend C drive

Unallocated space will be combined into C drive.

Unallocated space merged

In Summary

Though Windows 10 Disk Management has built-in Shrink and Extend Volume, it is useless if you want to extend a drive by shrinking other one. It is the most common issue that unable to extend C drive in Windows 10 Disk Management after shrinking D. NIUBI Partition Editor can move Unallocated space next to C drive, then this problem can be solved easily.

Better than Windows native Disk Management, NIUBI Partition Editor can resize a drive and generate Unallocated space on either side, and It can easily extend a drive with Unallocated space on either side, too. Besides resizing and moving partition, this partition software can merge, convert, copy, defrag, wipe, repair, scan partitions and much more.

Download to try