Resize/Adjust C drive on Windows 10

Updated on: November 16, 2019

This article introduces how to resize C drive on Windows 10 (32 & 64 bit). Adjust partition C to smaller or larger without losing data or reinstalling operating system.

C drive is allocated while installing Windows Operating System, sometimes you need to change partition size if it is too large or small. Unlike data partitions, C drive is where Operating System located, so you'd better pay more attention. This article introduces how to resize C drive partition with Windows 10 native Disk Management and third party software.

Adjust C drive space with Disk Management

The same with previous versions, Windows 10 has native Disk Management utility to resize C drive or any data partitions. The built-in Shrink Volume function can decrease partition size to make Unallocated space. Extend Volume can increase partition size with adjacent Unallocated space on the right side.

1. How to resize C drive to smaller size

To do this, press Windows and X on the keyboard and select Disk Management from the list, then follow the steps:

  1. Right click C drive and select Shrink Volume.
  2. Click Shrink to use default maximum space, or enter an amount in MB (1024MB=1GB) manually.

If there are unmovable files located in C drive, you can only shrink little space. Follow the steps if you can't shrink C drive with Windows 10 Disk Management.

Another limitation of Shrink Volume function: it cannot make Unallocated space on the left side of a partition.

Shrink C drive

2. How to resize C volume to larger size

With Disk Management, you can only enlarge C drive by deleting D (the contiguous partition on the right side).

There is Shrink and Extend Volume in Windows 10 Disk Management, why deleting drive D? Because Shrink Volume can only make Unallocated space on the right side when shrinking, Extend Volume cannot combine this nonadjacent space to C drive.

After shrinking D via Disk Management, you'll find that Extend Volume is grayed out for all other volumes:

Extend Volume greyed

Do NOT delete D if you installed programs in it, otherwise, all shortcuts and some programs will stop working even if you transfer all files from D to other volume.

If you can delete volume D, follow the steps:

  1. Right click C drive and select Extend Volume.
  2. Simply click Next in the pop-up Extend Volume Wizard window.
  3. Disk and space is selected by default, click Next or change manually.
  4. Click Finish to confirm and execute.

There is better method to increase C drive space in Windows 10 without deleting D.

How to adjust partition C by shrinking D

By shrinking a volume, part of unused space will be converted to Unallocated, all files in this volume keep intact. If you resize C drive by shrinking D or other volumes, Operating System, programs and associated settings keep the same with before.

When resizing hard drive on Windows 10, you'd better back up and select the safe partitioning software, because there is potential data loss and system damage risk. NIUBI Partition Editor is always suggested because of many advantages such as:

Comparing with Windows Disk Management:

  • Both NTFS and FAT16/32 partitions are supported.
  • Make Unallocated space on either side when shrinking a drive.
  • Extend partition with adjacent Unallocated space on either side.
  • Move and merge Unallocated space to nonadjacent partition.
  • Much easier, you just need to drag and drop on the disk map.

Comparing with other partitioning software:

  • 1 Second Rollback technology to ensure system and data intact.
  • Virtual mode technology to avoid incorrect operations.
  • Cancel-at-well - cancel incorrect but ongoing operations without data loss.
  • Hot-Resize technology to help extend C drive on the fly.
  • Adjust partition size much faster because of unique file moving algorithm.

Download NIUBI Partition Editor and you'll see initial disk partition size and structure on the right.

Main window

Steps to resize C drive partition on Windows 10 by shrinking D:

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

Shrink D

Drive D is shrank and Unallocated space is make on its left side.

Shrink D rightwards

Step:2 Right click drive C and select "Resize/Move Volume" again, drag right border towards right to combine the Unallocated space.

Extend C drive

As you see, C drive is resized from 30GB to 50GB.

Extend volume C

Remember to click Apply on top left to execute, otherwise, real disk partitions won't be modified.

How to resize C drive with another disk

If there is not enough free unused space in D drive, you can shrink other non-adjacent partitions in the same disk, then you just need an additional step to move Unallocated space next to C drive.

But if there is no other data volume in the same disk, no partitioning software can extend C drive with unused or existing Unallocated space from another separated disk. In this case, you can clone this disk to a larger and then adjust size with extra disk space.

In Summary

To resize C drive partition on Windows 10, the native Disk Management works under restricted condition. If you cannot shrink or extend C drive with this tool, you need safe partitioning software. Because of the enhanced data protection ability, NIUBI Partition Editor is the best choice.