By Cherry / Last Updated March 18, 2022

“Why can’t I resize my existing partition?”

I just download a new application and I want to install it on a new second partition. I freed up just over 50 GB from my hard drive and I was trying to shrink my existing partition, I’m using the Disk Utility, however, I was getting the partition failed with the error:

“The partition cannot be resized. Try reducing the amount of change in the size of the partition.”

What can I do with these? I don’t want to mess anything up even more.

Windows OS have built in Disk Management. Since Windows 8, the Disk Management has Extend Volume and Shrink Volume for resizing partition. However, it has many limitations:

1. The Extend Volume needs an unallocated space at the right side of the partition you want to extend, and it must adjacent to the partition you want to extend. Otherwise, the Extend Volume would be grayed out, and you cannot resize partition with the unallocated space.

2. Shrink Volume of Disk Management also has disadvantages. For example, it has a limitation of the shrink space. It only can shrink size at most half of the partition. Otherwise, the Shrink Volume will be grayed out. Besides, If there is any files stored on the end of the partition, or there are some bad sectors at the end of the partition, you cannot resize partition by shrinking volume, too.

How to resize Windows partition?

If you resize partition failed with Disk Management, you can try to take use of third party software to help you resize Windows partition easier. Here we highly recommend you AOMEI Partition Assistant, a free partition manager which can change partition size more flexible. Here you can follow the steps below of how to resize Windows partition hard drive.

Step1. Free download AOMEI Partition Assistant Standard, install and launch it. It will show you the basic environment of your disk(s). To change partition size, here you need to select the partition, right-click it, and select Resize Partition. Here we take use of shrink D:\ drive.

Resize Partition

Step2. Then, you will move to a window where you can resize partition by drag the bar or input the amount of the space you want to shrink. When you set up, click OK.

Shrink D Partition

Step3.Then, it will show you an uallocated space on the main interface, click Apply, and it will execute the task immediately.

When you got the unallocated space, you can extend partition with the unallocated space. AOMEI Partition Assistant allows you to move partition, so that you can move the unallocated space near to the partition you want to extend with the unallocated space. You can also use merge partitions function so that you can enlarge partition with the unallocated space directly.


If you have met the problem “Cannot resize partition”, you can try to use AOMEI Partition Assistant to resize Windows partition. Compared with Windows Disk Management, AOMEI Partition Assistant has a lot of advantages:

  • You can extend partition even the unallocated space is at the left side of the partition or the unallocated space isn’t adjacent to the partition you want to extend.

  • You can shrink partition as more as you can, without the limitation of “half partition”.

  • Besides resize partition, AOMEI Partition Assistant has many other features, like format partition, create partition, etc. And you can upgrade to AOMEI Partition Professional to get more functions like allocated free space, partition alignment, command line, etc. It is really a great tool for change partition size for Windows 7/8/10.