How to allocate more space to C drive in Windows 10/8/7

by John, Updated on: April 28, 2021

Disk partitions are allocated while installing Operating System or by computer manufacturers. Many people ask whether it's possible to 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 in Windows 10/8/7 without reinstalling Windows or programs. To allocate free space to C drive from other partition, you may use Windows native Disk Management tool or third party software. Selecting corresponding tool and method according to your own disk partition configuration.

Allocate more space to system C drive by deleting D

The same with previous Windows 7/8, Windows 10 has built-in Disk Management tool which can create, delete, format, shrink and extend partitions. Some people tried to shrink partition D/E and got Unallocated space but they cannot add this space to C drive. Because Disk Management can only extend a partition when there is contiguous Unallocated space on the right side. Unallocated space that shrunk from D drive is nonadjacent to C, therefore, Extend Volume is disabled for C drive.

If you want to expand C drive without any software, there must be a contiguous partition on the right of C drive, in addition, you must delete this partition to get contiguous Unallocated space.

Extend Volume greyed

How to allocate more space to C drive in Windows 10 with Disk Management:

  1. Press Windows + 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.
  • In Windows 7/8, press Windows + R, input diskmgmt.msc and press Enter to open Disk Management.
  • You'll lose data if you forget to transfer files before deleting D.
  • If drive D is a Logical drive, you cannot extend C drive even if you delete it.

Allocate more free space to C drive by shrinking D

If you want to allocated more disk space to C drive without deleting partition, you must run third party software. Better than Windows Disk Management, NIUBI Partition Editor can make Unallocated space on either left or right side when shrinking a partition. It can add Unallocated space to either contiguous and any nonadjacent partition on the same disk. To do this, you just need to drag and drop on the disk map. To Windows 10/8/7/Vista/XP home computer, there's free edition. Download

Steps to allocate more free space to C drive in Windows 10/8/7 with NIUBI:

Step:1 Right click partition D and select "Resize/Move Volume", drag left border towards right 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 towards right.

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, remember to click Apply on top left to confirm and execute.

Allocate more space to C drive from nonadjacent volume

If there is not enough free space in the adjacent drive D, you can allocate free space to C drive from any nonadjacent partition on the same disk. Follow the steps below:

Step:1 Right click drive E and select "Resize/Move Volume", drag left border towards right to shrink it and make Unallocated space on the left side.

Step:2 Right click drive D and select "Resize/Move Volume", drag middle position towards right in the pop-up window. Then, Unallocated space will be moved to the other side.

Move drive D

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

Reallocate disk space of C drive with another disk by cloning

If there is no other data volume or not enough free space on the same disk, the method above is invalid, because no software can move free space between two separate disks. Instead, you need to clone this disk to a larger one and reallocate partition with extra disk space. Follow the steps in the video. Besides reallocating disk space, NIUBI Partition Editor helps you do many other operations such as merge, move, convert, hide, defrag, wipe, scan bad sectors.

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