Hard drive used space plus free space doesn't add up

Windows Vista.

C drive says there are 56 GB out of 298 GB free.

But when I highlight all folders on the C drive (including hidden) and ask for “properties,” it adds up to 170 GB.

170 + 56 < 298, by a wide margin.

Any idea what’s going on here?


Do you have a ton of stuff in your recycle bin?

Is the system partition filling the entire drive? If it exists, the OEM recovery partition is usually on the same disk.

In addition to hidden files, are protected operating system files being shown?

Even with hidden and protected files shown, selecting all files does not include the System Volume Information folder, which is where system restore points and shadow copies are stored.

Uncheck the view bit which says “hide protected operating system files (reccomended)” and look again. You’ll find a couple more directories, including the recycycle bin and boot directory. And remember to count the files in c:/ itself. Among other things, you will find the pagefile there. Then, you should probably turn the view bit back on.

Another point - when you click on properties for a large folder, if it has to scan to add up all the sizes, you may have not let it finish before noting the number. In particular, the property screen for the Windows directory may pause a few times before it’s finished. If you are running Vista, that directory will be on the order of 20 GB.

They will never add up because they take different approaches to the addition.

Think of it this way when you store information you store it in a box. Let’s say you have 10 shoeboxes and you put one golf ball in each shoe box. That’s OK but wasteful. It’s better to put the 10 golf balls in one box.

So the different ways of looking at things produce different results. I recall the old days when memory was scarce and the IT guys told you don’t put icons on the desk top. 'Cause each one took up a whole BOX. So that was akin to putting one golf ball in one shoe box, instead of doing it correctly.

Here’s another simple example. You type a text and it is 3kb and you stick it in a folder. The compute may allocate 10kb for that document and folder. You type another 3kb document and stick it in a new folder. Well the computer allocates another 10kb. So for two documents you’ve allocated 20kb but when you add them up you’ve only actually used 6kb

This is oversimplifying it but what you’re most likely seeing is actual free memory versus accessible free memory

I really don’t think your explanation is the reason for the OP’s problem.

Sure, the way that computers store files means that you might not be able to use every single available byte of hard drive space, but there’s almost no way that this issue would explain a discrepancy of ~70Gb on a 300Gb drive.

The OP is on Vista, so his hard drive is probably formatted as NTFS. This file system is generally more space-efficient than the preceding FAT system, especially on larger hard drives.

One thing that can take up a bunch of space on a hard drive is your Restore points, at least in XP (not sure about Vista). A few weeks ago, my C: partition (which is only 40Gb, and is just for the OS and programs) was showing only about 5Gb of free space, despite the fact that running Treesize showed well under 30Gb of files on the drive. Deleting my old restore points freed up well over 5Gb of space.

I highly recommend Treesize, by the way. You can also use CCleaner to clean up things like your cache, temp files, and other things that might be taking up space.

By default, the System Volume Information directory will take 15% of your hard drive. That’s 45 GB right there. 170 + 56 +45 =271. You’ll also have a page file and hibernation file, each of 2-4 GB for 275-279 GB. And your drive may hold 300 billion bytes, but that’s only 280 x 2[sup]30[/sup] bytes. So the space on your hard drive is fully tallied.

Try this free program: http://windirstat.info/

It shows a graphical view of the files and folders on your hard drive (including hidden system files) so you can see at a glance where all the space is going.

If your drive is very large / full the initial scan can take a good few minutes though.