Make System C: Drive Bigger

by Jordan, Updated on: February 22, 2020

This article introduces how to make system C drive bigger without reinstalling Windows and programs.

Applies to: Windows 10, Windows 8, Windows 7, Windows Vista, Windows XP, Windows Server 2019, Windows Server 2016, Windows Server 2012 (R2), Small Business Server 2011, Windows Server 2008 (R2) and Windows Server 2003 (R2).

Recently some Windows 10 users ask me whether it is possible to make system C drive larger without reinstalling Windows, because C drive runs out of space. The answer is yes. You may either use Windows native tool or third party software to accomplish this task. Both Windows Disk Management and diskpart command has the ability to extend allocated partition, but because of some limitations, they are not the best tools. No matter which tool you select, you'd better make a backup first.

Make C drive larger with Windows Disk Management

Diskpart command tool is a bit complicated to personal computer users, here I only introduce how to make C drive bigger with Disk Management. Better than diskpart, Disk Management has graphical interface, it displays all disks with partition structure and Unallocated space (if there is). However, both native tools have same limitations and I'll talk about later.


  1. There must be another partition on the right side of C drive.
  2. This right contiguous partition (such as D:) must be Primary.
  3. You did not install programs in drive D, so you can delete it.
  4. Transfer all files in drive D to other place, otherwise, you'll lose data after deleting this partition.

How to make C drive bigger for Windows PC and Server with Disk Management:

  1. Press Windows and R on your keyboard to open Run, type diskmgmt.msc and press Enter to open Disk Management.
  2. Right click D: drive and select Delete Volume, then it will be changed to Unallocated space.
  3. Right click C: drive and select Extend Volume.
  4. Click Next till Finish in the pop-up Extend Volume Wizard window, then Unallocated space will be added into C drive.

Learn why cannot extend C drive with Disk Management by shrinking other volume.

Make system C drive bigger with free partition editor

Comparing with Windows native tools, third party software has advantages such as:

Among these software, NIUBI Partition Editor has free edition for Windows 10/8/7/Vista/XP home computer users. The most important, it has advanced technologies to protect system and data such as:

Steps to make C drive larger for Windows Server and PC with NIUBI Partition Editor:
  1. Download NIUBI PE, right click drive D and select "Resize/Move Volume", drag left border towards right in the pop-up window, or enter an amount in the box of Unallocated space before. Then drive D will be shrank and part of unused space will be changed to Unallocated on its left.
  2. Right click drive C and select "Resize/Move Volume" again, drag right border towards right in the pop-up window, then Unallocated space will be combined to C drive.
  3. Click Apply on top left to execute, done.

If you want to shrink a nonadjacent partition (such as E:), there's an additional step to move partition D before adding Unallocated space to C drive.

Video guide to make system C drive bigger:

Video guide

Make C drive partition bigger with another hard disk

In few computers, there's no other data volume or not enough free unused space on the same disk. In that case:

Then you can increase C drive space with additional disk space.

If you use Windows Server OS for local or virtual machine, you need a license of partition editor server.