How to add space to C drive on Windows 10

Updated on: May 17, 2019

This article introduces how to add space to C drive in Windows 10 (32 & 64 bit). 3 ways to add Unallocated or unused space to C partition without losing data or reinstalling Windows.

The same with other versions, C drive runs out of space in Windows 10 computer. In this situation, nobody likes to start from scratch. It can't be better if you can add more space to C drive without reinstalling Windows and all programs. If there is Unallocated or free unused space in other volumes of the same disk, you can add into C drive.

Unallocated space is blank and not belong to any volumes. Unused space in D for example can be converted to Unallocated, then converted to unused space again in partition C.

To add space to C drive in Windows 10, there are two options: Windows native Disk Management and 3rd-party partition software. In this article, I'll introduce 3 ways to add disk space to C drive in Windows 10 with both tools.

Add Unallocated space to C drive by deleting D

Windows Disk Management can only delete the adjacent partition (D:) to expand C drive.

Although there is advanced Shrink Volume and Extend Volume functions in Windows 10 Disk Management, you cannot expand C drive by shrinking D, because:

Shrink Volume can only make Unallocated space on the right side of D, Extend Volume can't combine Unallocated space to nonadjacent partition (C:) or the right partition (E:).

Extend Volume greyed out

If you can delete partition D, there will be adjacent Unallocated space, then Extend Volume is enabled for C drive.

Steps to add disk space of D into C:

  1. Press Windows and X on the keyboard to open Disk Management.
  2. Right click D and select Delete Volume.
  3. Right click C and select Extend Volume.
  4. Finish pop-up Extend Volume Wizard by several clicks.

Transfer files to other partition before deleting D. Do not delete it if you installed program in it.

Add unused space to C drive by shrinking D

Obviously, it is better to increase C drive by shrinking D to transfer unused space. In this way, you won't lose partition. Programs and associated settings, Operating System and anything else keep the same with before.

Steps to add unused space to C drive in Windows 10:

Step 1: Download NIUBI Partition Editor, right click drive D: and select "Resize/Move Volume", drag left border towards right in the pop-up window.

Shrink D

20GB unused space of D is converted to Unallocated on the left side.

Shrink D rightwards

Step 2: Right click drive C: and select "Resize/Move Volume" again, drag right border towards right in the pop-up window.

Extend C drive

Then 20GB Unallocated space is added into C drive.

Extend volume C

This software works in its virtual mode and the operations you do are listed as pending. To modify real disk partition, you need to click Apply to confirm and execute.

Add space to C drive from nonadjacent volume

In some computers, there are not plenty of unused space in the adjacent partition (D:), then you can get space from any non-adjacent partition in the same disk.

Follow STEP 1 to shrink the nonadjacent partition (E:) and make Unallocated space on the left side. Before adding Unallocated space to C: drive, you need an additional step to move Unallocated space.

To do this, right click partition D: and select "Resize/Move Volume", drag middle position rightwards in the pop-up window.

Move drive D

Add space to C drive from other disk

In some computers, there is no other volume or not plenty of unused space in all other partitions. Some people want to add space to partition C from other separated disk. No partitioning software can do this, because hard disk is physical unit and its size is fixed.

In this case, you can copy disk to a larger one with NIUBI Partition Editor. While copying, the extra disk space can be added into C drive.