Shrink C partition

Shrink C drive partition on Windows Server 2016

Sometimes you need to shrink C drive in Windows Server 2016, for example: you forgot to edit disk and create more partitions when installing Operating System, so all available disk space are occupied by C drive. As we know, it is a bad idea to put everything into system C partition. Then what to do now, start from scratch? No, you can shrink partition C in Server 2016 Disk Management, then part of the unused space in C drive will be converted to Unallocated space, which can be used to create more volumes.

Shrink C partition

Shrink partition C with Disk Management

Windows Server 2016 native Disk Management utility provides Shrink Volume functionality to decrease partition size on the fly. It is easy and fast, however, you can’t shrink C drive in some situations.

Steps to shrink C: drive in Server 2016 Disk Management:

Step 1 Right click Windows on bottom left of the screen and then select Disk Management.

Step 2 Right click C drive and select Shrink Volume.

Shrink Volume

Waiting for Disk Management to query available free space.


Step 3 Enter the amount of space in MB and click Shrink, here I entered 122880.

Enter amount

In a short time, system C partition is shrank to 39.45GB, 120GB free space of it is now converted to Unallocated behind it.

C drive shrank

It is easy to shrink partition C in Server 2016 Disk Management, but as I said above, you cannot shrink C drive in some situations.

Cannot/unable to shrink C drive

In fact, Shrink Volume only supports NTFS partition, when you shrink a FAT32 partition, Shrink Volume is greyed out. Never mind, the system partition C is formatted as NTFS by default when installing.

The most common reason why you unable to shrink C drive is caused by inconsistent available space. This issue is very likely occur when you use default maximum space.

Cannot shrink C

When I click Shrink, I received the error message “There is not enough space available on the disk(s) to complete this operation.”

Error message

When I shrinking C drive, the available space to shrink is 150264MB. Before I click Shrink, if any Windows Update or other files saved into C drive, the available free space is less than 150264MB. So, I cannot click Shrink with original maximum amount.

Cannot shrink volume C beyond half limit

Many people feedback that they can only shrink little space, or unable to shrink C drive beyond half size. There seems to be some limit that prevent shrinking more space, even though there is large amount in C drive.

This issue is caused by “unmovable” files. In the Shrink window, there is a tip “You cannot shrink a volume beyond the point where any unmovable files are located.

Tip of shrinking

For example: there are 4 blocks in C drive. If the unmovable files are located in block 3, you cannot shrink volume C to block 2 even though it is blank.

Shrink C drive

There is no tool to identify which and exact position of the unmovable files. However, this is not an issue to disk partition software, because it can move the unmovable files.

Decrease C drive with partition software

Better than Server 2016 built-in Disk Management, NIUBI Partition Editor can move the location of all files when shrinking C or other partitions. In addition, it reserves about 1GB free space if you shrink C drive to minimum size. Thus, the issue above won’t occur with NIUBI. To shrink C drive partition in Windows Server 2016, you just need 1 step to drag on the disk map.

Download NIUBI Partition Editor, right click C drive and select “Resize/Move Volume”.

Resize Volume

In the pop-up window, drag either border towards the other side. If you drag right border leftwards, Unallocated space is produced on the right side of C drive.

Drag to shrink

Click OK, C drive is shrank.

C drive shrank

Tips This partition software is designed to work in virtual mode, the operations you do will be listed as pending on bottom left, real disk partition won’t be modified until click Apply to confirm.

In Summary

Windows Server 2016 provides native Shrink Volume functionality in Disk Management, but it is not a perfect tool to decrease partition size. Only NTFS partition is supported, Unallocated space can only be produced on the right side. The worse, you cannot shrink C drive or can only shrink little space. To shrink hard drive in Windows Server 2016, NIUBI Partition Editor is better choice. Besides shrinking volume, it helps you extend, merge, copy, convert, scan, wipe disk partition, etc. Better that other tools, it is integrated 1 Second Rollback technology to ensure system and data intact when modify disk partitions.