How to Add Unallocated Space to C Drive

The C drive is the default installation location for the Windows operating system. So it’s crucial to ensure that there is adequate free space in the C drive for Windows to operate smoothly. If you’ve got unallocated space in your disk, you have the option to extend the storage space on your C drive by incorporating this space. You can either use the built-in Disk Management or Diskpart utility to extend your C drive space.

Using Disk Management

The Disk Management utility is the simplest way to add unallocated space to your C drive. Here’s how you can do so:

1. Press Windows + R to open the Run utility.
2. Type diskmgmt.msc and press Enter to open Disk Management.
   
3. Right-click your C drive partition and select Extend Volume.
   
4. In Extend Volume Wizard, click on Next.
5. Next to Select the amount of space in MB, enter the amount of unallocated space you want to add to C drive in MB. (One GB is equal to 1024 MB.)
   
6. Click on Next, and select Finish.
   

Using DiskPart

Another way you can add unallocated space to your C drive is by using the DiskPart utility. However, like Disk Management, you can only add unallocated space adjacent to the C drive.

1. Launch the Run box using the Windows + R shortcut key.
2. Type diskpart and press Enter to open it.
   
3. Type list disk and press Enter. It will show you all the disks connected to your computer.
4. Note the disk number which contains your C drive. Enter the command select disk 0. The C drive is usually in Disk 0. If it is on a different disk, change 0 to the disk number.
   
5. Type list partition and press Enter to see all the partitions in that disk.
6. Note the partition number of the C drive. Enter the command select partition <0>. Replace <0> with the partition number of the C drive.
7. Type the command extend size = <unallocated space> and press Enter. For example, the extend size = 1000 command will add 1000 MB of unallocated space to the C drive.
   
8. Exit Diskpart.

Adding Non-Adjacent Unallocated Space to C Drive

If you want to add non-adjacent unallocated space to the C drive, you will need to use some unconventional means. The only way to natively do so is by moving the unallocated space next to the C drive.

So, let’s see how you can move the unallocated space next to the C drive.

1. Back up the drive adjacent to C Drive in an external storage media.
2. Open Disk Management.
3. Right-click the partition that is between the C drive and the unallocated space.
   
4. Select Delete Volume, and click on Yes. (Deleting the volume will leave behind corresponding unallocated space next to the C drive.)
   
5. Add the necessary amount of unallocated space to the C drive using the above method.
6. Right-click on the remaining unallocated space, and select New Simple Volume.
   
7. Click on Next, and enter the amount of space you want to allocate to that drive.
   
8. Click on Next again, and assign a drive letter to your new drive from the drop-down menu.
   
9. Select Next and Next again.
10. Click on Finish.
    
11. Now, move your backup data to that new drive again.

If you’ve got a recovery partition between your C drive and unallocated space, you won’t be able to delete the recovery partition from Disk Manager. You’ll need to use DiskPart to do so:

1. Open DiskPart.
2. Type list disk and press Enter to view all the disks connected to your computer. (Note down the number of the disk containing the C drive.)
3. Enter the command select disk <number>. (Replace <number> with the actual number of the disk containing the C drive. For example, select disk 0)
   
4. Type list partition and press Enter.
5. Enter the command select partition <number>. Replace <number> with the drive number of the recovery partition.
6. Type delete partition override and press Enter to delete the recovery partition.
   
7. Now, use the Disk Management method to add the unallocated space to your C drive.

Lastly, there is another way you can add non-adjacent unallocated space to your C drive. You can use advanced third-party software that directly does so without backing up and deleting interfering partitions.