How to calculate the used file space on C?

[OldGrantonian]

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I have Win 7 Home Premium, 500 GB disk.

I'm getting a "low disk space" message for drive C.

Using "Properties" for C, I can see that the used space on C is 307 GB, and free space is 6.5 GB.

Note that when my laptop was new, I moved my entire "Documents" folder to the E: partition, using Windows tools. I have plenty of free space to shrink E, and increase C, using Partition Wizard.

My problem is that if I use "Properties" for each high-level folder, and sum the sizes for all the folders on C, it only comes to 55 GB. (That includes $RECYCLE.BIN. All hidden folders are shown.)

IMHO: 55 GB is too low, and 307 GB is too high

What am I doing wrong?
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[ignatzatsonic]

What am I doing wrong?

Maybe nothing.

You can't rely on a "sum of the folders" calculation to be accurate.

I'd download Tree Size Free to get more details on what is using space.

TreeSize Free - Quickly Scan Directory Sizes and Find Space Hogs

 

[OldGrantonian]

I'd download Tree Size Free to get more details on what is using space.

Wow!

TreeSize shows that 80% of my C drive is being used by my Chines_, Russi_n, and North Kore_n friends to store all their wedding anniversaries in my "System Volume Information" (screenshot).

According to Windows Explorer, this file has zero bytes. TreeSize says the file is 248.9 GB, and uses 80% of my C partition.

The screenshot shows that the "bloated" Windows system only takes 10% of my C partition. (Linux fits on a 256 KB floppy - which I still have).

Thanks to ignatzatsonic
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[ignatzatsonic]

I'm not sure what you mean by Russian, Chinese, and North Korean friends.

The biggest files in the System Volume Information folder are usually various "System Restore" points, which can eat up gigabytes quickly.

Have you popped open that folder via the + sign shown next to that folder in Tree Size Free? Whatever's in it will spill out.

The System Restore points typically have a very long file name with seemingly random characters and are usually at least 1 GB each.

But maybe you've already looked in it and have attributed to your "friends" in Asia. I dunno what your cryptic remark means.