Windows 10: C-drive shows more "used" space than folders all together

I am monitoring the free space on a C-drive on two different Win10 PCs.I have noted the "size" of each folder in the C-root - including two "hidden folders".When calculating the overall size by adding up each folder in GB, I find on one PC that I have a fairly good match with the general "used" number found when I right-click the C-drive and show "properties". The "sum of all folders" is within +/- 2 GB of the "used" value of around 67 GB. "Free" is 35 GB and "Capacity" is 101 GB.On the other PC, I however find that there is a much bigger difference. The "used" value at 93 GB is 14 GB bigger

:)

 

Discrepancy between 'Used Space' on C drive and total of actual folders/files

According to 'Properties' in Windows Explorer, my C drive (one of four partitions on my primary drive) has 296GB 'Used Space' and 272GB 'Free Space', giving a total partition size of 568GB. However, if I add up the total space occupied by all the folders
and files on C drive that are listed in Windows Explorer they come to roughly 44GB. (The largest folder is Windows (19.5GB), followed by Users (9GB) and Program Files (5.8GB). The rest of the folders are smaller than this.). Nearly all my applications, data,
photos, videos, backups etc are on the other three partitions on the primary hard drive or on a secondary internal hard drive.

Can anyone suggest what accounts for the HUGE discrepancy between the reported 'Used Space' and the total of the actual folders/files? I first noticed this when backing up my C drive using Acronis TrueImage, which yields a back up file of 218GB - presumably
the 296GB with some compression. A few months back I recall that the Acronis backup files were sized at around 60-70GB, so there's something funny going on! If there is some giant folder or file that is lurking on my C drive, what could it be and why isn't
it showing up in Windows Explorer?

 

Unallocated Space to C Drive

Thanks

 

Unallocated Space to C Drive

Hi Travis,

It appears that a disk partition was created but was never assigned its allocation. Assuming there are no files stored in the unallocated partition, perform these steps to combine it with your C: drive:

• In Disk Management, right-click on (C which appears next to the
  Unallocated partition.
  
• Select Extend.

Let us know if you're able to combine the spaces after following the steps above.

Regards.