How to reallocate more space to C drive in Windows 10

Published on: May 17, 2019

This article introduces how to allocate more disk space to C drive on Windows 10 (32 & 64 bit). Reallocate disk space from other partition without losing data.

Disk partitions are allocated while installing Operating System or by computer manufacturers. However, you can reallocate disk space without losing data when a volume is running out of space. In this article, I'll introduce several ways to allocate more space to C drive on Windows 10 with native Disk Management tool and third party partition editor software.

Allocate more space to system C drive by deleting D

The same with previous Windows 7, Windows 10 has built-in Disk Management utility, which can create, delete, format, shrink and extend partitions. Extend Volume function can extend a partition when there is contiguous Unallocated space on the right side. But, Shrink Volume cannot make Unallocated space on the left side when shrinking a partition. So, Extend Volume is disabled for C drive after shrinking D, because Unallocated space is non adjacent.

Extend Volume greyed

If you want to allocate more space to C drive with Windows 10 Disk Management, follow the steps:

  1. Press Windows and X on your keyboard and select Disk Management.
  2. Right click drive D and select Delete Volume.
  3. Right click drive C and select Extend Volume, click Next in the pop-up window.

Caution

  • You'll lose data if you forget to transfer files before deleting D.
  • All shortcuts and part of programs in drive D will stop working after deleting even if you transfer all files to other volume.
  • If drive D is a Logical partition, you cannot extend C drive even if you delete it.

Allocate more free space to C drive by shrinking D

If you shrink volume D, part of unused space will be converted to Unallocated, all files keep intact. Obviously, it is better to shrink D than deleting. However, as I explained above Disk Management cannot help you shrink D to extend C. To do this, you need professional partitioning software.

Download NIUBI Partition Editor and follow the steps below:

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

Shrink D

20GB unused space 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 rightwards.

Extend C drive

Unallocated space is allocated to C drive.

Extend volume C

This software is designed to work in virtual mode, to reallocate real disk partitions, you need to click Apply on top left to confirm and execute.

Allocate more disk space to C drive from E

If there is not enough unused space in the adjacent drive D, you can allocate free space from E or other partitions in the same disk. Follow the steps below:

Step:1 Right click drive E and select "Resize/Move Volume", drag left border rightwards to shrink it and make Unallocated space on the left side (similar with Step 1 above).

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

Move drive D

Then, Unallocated space will be moved to the other side.

Step:3 Right click drive C and select "Resize/Move Volume" again, drag right border rightwards to combine Unallocated space.

In a word, drag the border towards the other side, you can shrink a volume or extend a volume with adjacent Unallocated space. Drag the middle position, you can move partition and Unallocated space.

Reallocate disk space of C drive by cloning

Many Windows 10 computers use SSD for Operating System, but this disk is not large. If there is no data volume (such as D:) or not enough free space in other data volume, you need to clone this disk to a larger one with NIUBI Partition Editor.

Because, NO partitioning software can extend a partition by getting space from another separated disk. While cloning, extra disk space will be shown as Unallocated space on the end, which can be allocated to C drive and other partitions.

This article introduces the full solution to allocate more space to system C drive on Windows 10. Check your disk partition layout and choose appropriate method.

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