How to add space to C drive in Windows 10

Published on: May 17, 2019

This article introduces how to add space to C drive on Windows 10 (32 & 64 bit) without losing data. Drag and drop to add free space to C from D or other partitions.

When C drive is full in Windows 10, you can add more free space from D or other partitions in the same disk. Then you can fix this issue fast and without reinstalling Operating System and programs. To do this, there are two choices with Windows native Disk Management and third party partition manager software.

Add disk space to C drive with Windows 10 DM

Some people like to use Windows built-in tools, thinking they have best compatibility. But in fact, Disk Management is not the best tool if you want to add disk space to C drive from other volumes.

Firstly, let's see the only way to add space to C drive with Windows 10 Disk Management:

  1. Press Windows and X on the keyboard and then select Disk Management.
  2. Right click partition D (the contiguous partition on the right side of C drive) and then select Delete Volume.
  3. Right click C drive and select Extend Volume.
  4. Click Next till Finish in the pop-up Extend Volume Wizard windows.

Then the disk space of volume D will be added into C drive.

Two things you should know before doing the steps above:

There is Shrink Volume in Disk Management, why not shrinking partition D instead of deleting? Because this function can only make Unallocated space on the right side of D, Extend Volume cannot combine Unallocated space to the right contiguous (E:) or nonadjacent partition (C:).

Extend Volume greyed

So, the only way to enable Extend Volume for C drive is by deleting D to get right adjacent Unallocated space.

If D is a Logical partition, you cannot add its disk space to C drive even after deleting it.

If Disk Management can shrink D and make Unallocated space on its left side, there is no such issue.

How to add free space to C drive from D (contiguous)

Obviously, the destructive way to delete D is not good. You'd better run partition editor software to shrink D and transfer free space to C, then Operating System, programs and everything else keep intact.

Better than other software, NIUBI Partition Editor provides unique 1 Second Rollback, Virtual Mode and Cancel-at-well technologies to protect system and data. It is recommended as the safest and fastest tool.

Download it and you'll see initial disk partition size and other parameters.

Main window

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

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

Shrink D

Part of free space in drive D is converted to Unallocated on the left side.

Shrink D rightwards

Step:2 Right click partition C and select "Resize/Move Volume" again, drag right border towards right.

Extend C drive

Unallocated space is added into C drive.

Extend volume C

Click Apply on top left to execute, done. (All operations before clicking Apply only work in virtual mode.)

How to add space to C drive from E (non adjacent)

If there is not plenty of free space in volume D, you can get from the non-adjacent drive E. Right click E and follow Step 1 above to make Unallocated space on the left side. Then you need an additional step to move Unallocated space next to C drive.

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

Move drive D

If there is no other volume in the same disk, you can copy this disk to a larger one with NIUBI Partition Editor. No partitioning software can add space to C drive from other separated disk.

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