How to Increase Space in C Drive Using Disk Management?

February 1, 2019

To increase space in c drive using disk management, first delete volume right behind partition C and then extend volume C with the unallocated space.

Computer Pops Up “Low Disk Space” Warning

After long time usage of our computer, it will pop up a warning message says “Low Disk Space – You are running out of disk space on system (C:) To free space on this drive by deleting old or unnecessary files, click here…”

Low Disk Space WarningAs the message has make it clear, the computer system partition is in low disk space problem. It will influence the performance of operating system; the most common presence is that computer becomes slower and slower. As the message also mentioned, we can remove unused files to get free space. It does help but cannot solve this problem completely.

If we do clear out system C partition and does get it released, after a period of time, low disk space problem probably will come back. Delete unnecessary files will only free a small part of disk space; it can only keep away from the warning message for a short period of time.

To completely solve low disk space problem, we should allocate free space to C drive form unallocated space or other partitions.

How to Increase Space in C Drive Using Disk Management?

Yes, we can increase space in c drive using Disk Management (DM). Yet, only when there is unallocated space very behind C drive, can it be increased by DM. Otherwise, will C drive extend volume greyed out. If there is unallocated space, how to move unallocated space to c drive? If there is not, how to allocate free space from one partition to another?

Extend Volume Greyed out

Thus, we should first create unallocated space and make sure it locates right behind system partition. Then, extend C drive with the unallocated space. To make unallocated space, we can either shrink some from other partitions or by deleting existing partitions. However, the unallocated space must be located very behind partition C. Therefore, the only choice is to delete the volume which lies very behind C and make it unallocated.

How to Increase C Drive Space from D Drive?

Next, I will show an example of how to increase c drive space from d drive (the drive which is very behind C).

Step1. Open Disk Management, right click partition D and choose Delete Volume.

Delete Volume


  • The data on volume D will be deleted. Make sure the crucial data on this partition has been backed up or moved to another safe place.

Delete Volume Warning

  • If the volume to be deleted is in use, it will inform us of that. We can force the deletion of the partition. Yet, forcing a deletion might cause unexpected errors in the application that is using this partition. Please be careful.

Force Delete Volume Warning

Step2. The process completes in seconds. When it finishes, we can see the space originally belongs to D volume becomes unallocated space and locates very behind C drive.

Make D Volume Unallocated

Tip: If the unallocated space is not enough, we can continue to delete the next partition to create more unallocated space.

Step3. Right click on C drive and select Extend Volume.

Extend Volume C

Step4. Extend Volume Wizard will pops up. Just click Next to continue.

Extend Volume Wizard

Step5. In this window, select the disk(s) from which we want to get free space. Here, both partition C and the deleted D partition is on Disk 0, and Disk 0 is the only disk from which we can take free space. Thus, Disk 0 is automatically selected for us. Specify how much free space we want to add into C drive (in default, it will merge all unallocated space into target volume), then click Next.

Extend Volume Wizard Select Disks

Tip: Even if there is another hard disk and there is much unallocated free space on it, we can’t add the unallocated space to the C drive for a basic disk volume can’t own space on more than one hard disks. The space of dynamic disk volume can lies on different hard drives. Thus, if the basic volume we are going to extend lies on a hard drive which only contains data, we can first convert the whole disk into dynamic, and then extend the volume (now becomes dynamic volume) with unallocated space on another hard disk (it should also be dynamic disk). If the basic hard disk has system installed on it, we are not recommended to turn it to dynamic. Convert a system basic disk to dynamic may cause system unbootable. To conclude, to extend a system basic disk partition, there must be an unallocated space on this disk and right behind this partition.

Step6. This is summary of the operation DM will carry out. Check it carefully. If it is all right, click Finish.

Extend Volume Wizard Confirm

Step7. In only a few seconds, we can have our system C drive extended.

Extend Volume C Completed

Allocate Free Space from One Partition to Another without Formatting Hard Drive

As we can see above, Disk Management can help us extend system C drive in seconds. However, the disadvantages is that it has to format other drives to allocate free space from one partition to another. Yet, is there a way to allocate free space from one partition to another without formatting hard drive?

To allocate free space from one partition to another without formatting hard drive, we should rely on third party software like AOMEI Partition Assistant.

PA Pro

With its Extend Partition Wizard, Resize Partition or Allocate Free Space feature, no matter which one, we can increase space in C drive without formatting other drives when there is no unallocated space on the hard disk.