How to extend OS partition drive on Windows 10

Updated on: November 16, 2019

As we know, many types of files are writing into the OS partition continuously, so it is very likely running out of space after a period of time. Many people ask if it is possible to extend the OS partition without reinstalling Windows and programs. To extend OS drive on Windows 10, there are 2 options by native Disk Management or third party disk partition software.

Windows 10 Disk Management only works under very restricted condition. Professional partitioning software is much more powerful, however, you should take care of your data, otherwise, there is potential data loss risk with unreliable software. In this article, I'll show you how to extend OS partition in Windows 10 with both Disk Management and safe partition software.

Extend OS partition

Extend OS partition with Windows 10 Disk Management

Some people like to use Windows built-in utilities, to extend disk partition, Windows built-in Disk Management indeed has the ability but not for all, because of many restrictions.

Together with Extend Volume functionality, there is Shrink Volume that is able to decrease size of allocated partitions. Some people try to shrink D and then extend the OS drive, actually, it is impossible. Windows Disk Management can only shrink drive D towards left and make Unallocated space on the right side, but to extend C drive with Extend Volume, Unallocated space must be on the left side of drive D. This is the reason why many people feedback that Extend Volume is disabled for C drive.

As you see, I can't extend system partition after shrinking drive D:

Cant extend OS drive

The only option to extend OS C drive in Windows 10 Disk Management is by deleting the adjacent drive (D:).

  1. Press Windows and X on the keyboard and select Disk Management from the list.
  2. Right click drive D: and select Delete Volume.
  3. Right click C: drive and select Extend Volume.
  4. Simply click Next till Finish in the Extend Volume Wizard window.

Do NOT do this if you installed programs to drive D. Remember to back up or transfer files before deleting.

Extend OS drive with partition software

With partition software such as NIUBI Partition Editor, you can extend the system partition C without deleting other drive.

It is able to shrink drive D to the right side and produce Unallocated next to C drive, then you can easily extend the OS partition in Disk Management or with NIUBI.

Steps to extend OS partition C on Windows 10:

Step 1: Download NIUBI Partition Editor, right click drive D: and select Resize/Move Volume.

Resize volume

Drag the left border rightwards to shrink it, you may also enter an amount in the box behind Unallocated space before. (1024MB=1GB)

Shrink D

Then Unallocated space is produced on the left side of D.

Drive D shrank

Step 2: Right click C drive and select "Resize/Move Volume" again, drag the right border rightwards to combine the Unallocated space in the pop-up window.

Extend C

Click OK, system partition C is extended to 50GB, click Apply on top left to execute.

OS partition extended

NIUBI Partition Editor is designed to work in its own virtual mode, the 2 operations are listed as pending on bottom left. If you want to cancel these operations, click Undo. To modify real disk partition, click Apply to take effect.

Watch the video how to extend os partition C on Windows 10:

Video guide

In Summary

Windows 10 native Disk Management can only help you extend the os partition by deleting the adjacent partition. This destructive way is not suggested. The best way is running safe partition software to shrink other partitions to get unused space. Better than other tools, NIUBI Partition Editor has Virtual mode1 Second RollbackHot-ResizeCancel-at-Will technologies and advanced file-moving algorithm to help resize and extend disk partition fast and safely.