How to extend system partition on Windows 10

Updated on: May 17, 2019

This article introduces how to extend system partition in Windows 10 (32 & 64 bit) without losing data. Shrink & move data partition to extend system volume C by drag and drop.

Comparing with data drives, system partition is more likely running out of space. To data volumes, you can easily transfer files to other place, but to system partition, it is much more complicated. You should expand it keeping Operating System and all programs intact.

To many people, it is a bit complicated, so in this article, I'll show you how to extend system partition in Windows 10 losing any data.

Difference between System and Boot partition

To many computer users, System partition is the drive that Operating System is located, but it's wrong.

  • The System partition is a primary partition that contains the files for booting Windows, files include Ntldr, Boot.ini,, bootmgr, BCD, etc.
  • The Boot partition is the partition where Windows is installed, it contains the operating system folder/directory.

Before Windows 7, System and Boot partition are the same one - "C:" drive. But from Windows 7, new added BitLocker requires an unencrypted partition, so System partition is separated from C drive.

Never mind, to avoid misunderstanding and call as traditional, I indicate C drive as system partition.

System Boot partition

Extend system partition with Disk Management

Windows 10 Disk Management inherited Shrink and Extend Volume from Windows 7, so you can change size of allocated partition without losing data. However, it has restrictions the same with previous versions:

  • Only NTFS partition is supported, another command FAT32 partition can't be shrank and extended.
  • Shrink Volume can only shrink a partition towards left and make Unallocated space on the right side.
  • Extend Volume can only combine Unallocated space to the left adjacent partition.

After shrinking drive D, you'll find that Extend Volume is disabled for both C and E drive.

This is because that Unallocated is non-adjacent to C drive and is on the left side of E.

Extend volume disabled

The only way to extend system partition C with Disk Management is by deleting drive D, then there will be adjacent Unallocated space behind C drive. However, don't do this if you installed programs in D.

Steps to extend system partition with Windows 10 Disk Management:

  1. Transfer all files in drive D to other partition.
  2. Press Windows and X on your keyboard and click Disk Management in the list.
  3. Right click the adjacent drive (D:) and select Delete Volume.
  4. Right click system drive C and select Extend Volume.
  5. Simply click Next to complete the Extend Volume Wizard.

If D is Logical partition, you can't extend system partition even by deleting D, learn why.

Extend system drive with partition editor

Comparing with Windows 10 native Disk Management, third party professional partition software is much more powerful. However, not all partitioning software can accomplish this task well.

In fact, there is potential system and data damage risk, because all parameters of related disk, partition and files must be modified absolutely correct. Some system boot related files must be updated, too. Some unreliable software could cause Windows boot failure and data loss.

Better that other tools, NIUBI Partition Editor provides unique technologies to protect system and data, for example:

Download and install NIUBI Partition Editor, you'll see the main window with disk partition structure and other information.

Main window

There are 3 ways to increase system partition size according to your own disk structure.

1. Extend system partition C by shrinking D

In most of computers, there is another drive (D:) in the same disk, NIUBI can shrink it and transfer unused space to C drive. In this way, Operating System programs and associated settings, as well as anything else keep the same with before.

Steps to extend system partition in Windows 10 with NIUBI:

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

Shrink D

Then part of unused space in D is converted to Unallocated on the left side.

Shrink D rightwards

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

Extend C drive

Then system C drive is extended from 30GB to 50GB.

Extend volume C

Step 3: Click Apply on top left to execute, done.

2. Extend system volume C by shrinking E

In some computers, there is not enough unused space in the contiguous partition D. In that case, you can shrink the non-adjacent drive (E:) to get unused space.

Similarly, right click E and follow STEP 1 above to make Unallocated space on the left side. Before combine Unallocated space into C drive, there is an additional step to move Unallocated space from right of D to the left side.

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

Move drive D

3. Extend system drive with other disk

In some computers, there is no other data volume, or not plenty of unused space in all other partitions. You can clone this disk to a larger one, and then system partition with extra disk space.

No partitioning software can extend a partition by taking space from another separated disk. Because the size of a disk is fixed, a 256GB disk can't be decreased to 200GB or increased to 300GB.

Follow the steps in the video to extend partition by cloning.

Video guide

In Summary

To extend system partition drive on Windows 10, the native Disk Management is useless in most cases. You'd better back up and use safe partitioning software. NIUBI Partition Editor provides powerful technologies to protect system and data, and several ways to extend disk partition easily. It also helps you merge, convert, defrag, wipe, hide, create, delete, format, scan partition, etc.