By Bryce / Last Updated August 21, 2020

The case: need to increase C capacity

“After upgrading to Windows 10, my C drive (the partition with the system installed) is nearly full. The Windows 10 hard drive has been divided into three partitions. Partition E and Partition F are almost empty. How can I shrink partition E and then extend partition C?”

A free partition resizer for Windows 10/8/7

When there is no unallocated space contiguously behind the to-be-extended partition, the Extend Volume option will be greyed out in Windows Disk Management. If you shrink partition, the emerging unallocated space is behind the shrunk partition and is not behind partition C. You need to delete partition rather than shrink partition behind the to-be-extended partition to get such unallocated space. To extend partition like partition C without partition deletion, you can turn to a free partition resize tool, AOMEI Partition Assistant Standard.

It can combine partition C or other partitions with non-adjacent unallocated space to increase partition size.
It is compatible with all Windows operating systems from Windows XP to Windows 10, then you don’t need to worry about whether it will still work after upgrading Windows.
It is with an intuitive and user-friendly interface, enabling you to handle it rather easily even you are new to this tool.

Step-by-step guide on resizing partition via the freeware

Free download the software, install, and run it. then check out those steps on how to extend system partition or other partitions when there is no unallocated space on the hard drive.

✔ Part 1. Detailed steps on shrinking partition beyond limits

Those steps are about decreasing the size of the partition that has much unused space to gain unallocated space. If there is non-adjacent/adjacent unallocated space on the hard drive, you can skip this part.

Step 1. Right-click the partition with much free space and choose "Resize/Move Partition". Here partition D is the partition that will be shrunk.

Shrink D Drive

Step 2. Put the mouse on the border and draw the double-headed arrow leftward to shrink partition D as you want. Then, click “OK” button.

Step 3. You’ll be in the main interface of the partition manager. Click “Apply” to commit the operation.

After shrinking partition F, you’ll find there is unallocated space contiguously behind partition F.

✔ Part 2. Detailed steps on combining partition with non-contiguous unallocated space

Those steps are about how to extend partition by adding non-adjacent unallocated space. Supposed that you want to extend system partition C, and the unallocated space is behind partition D.

Step 1. Right-click partition C and choose “Merge Partitions”.

Step 2. Tick the Unallocated Space and click “OK”.

Note: If there are multiple pieces of unallocated space on the same hard drive, it’s available to merge all of them into the partition that you need to enlarge. Or you can combine these pieces of unallocated spaces into one piece of large unallocated space and create a partition on it.

Step 3. Return to the home interface automatically, click “Apply” to extend the partition.

After that, you can see that system partition has been extended.


  • The “Merge Partitions” function can combine two partitions into one as well.

  • To enjoy more functions of the partition software, like recovering lost partition, splitting one large partition into two small partitions, you can upgrade to Professional version.

Wrap things up

When system partition has little unused space left, the performance of PC can be affected. If partition C has no unallocated space that is adjacently behind it, you are unable to extend it using Disk Management.

In such a case, turn to a third-party free partition resizer can be an easy way to extend the partition. All you need to do is just to shrink a partition with much free space and then enlarge system partition with the non-contiguous unallocated space after shrunk partition. This tool can also help you to extend other partitions without losing data.