Used space discrepancy on an old decrypted drive

[Netherspark]

A while ago I used to have a USB drive for sensitive work-related stuff, encrypted with Truecrypt (before Truecrypt become obsolete). But at some point it must have become corrupted because one time I loaded it and all the files were just random letters and numbers, and I couldn't seem to do anything to 'fix' it.

Accepting that all the data was lost, I reformatted and drive-wiped it, which was supposed to remove the encrypted volume and basically make it a normal USB drive again. But when I look at the drive's properties there's a discrepency in the free/used space.

It's an 8gb drive, and it says I have 7.8gb free space, but next to that it also says 7.26gb free space - that's a discrepency of about 500mb, which is the same amount of data that was on it before. But as far as I can tell the drive is completely blank, and Truecrypt can't find any encrypted volumes on it, but that 500mb is still unaccounted for.

So is all that corrupted encrypted data still sitting around, invisible and inaccessible? Some sort of glitch? If the data is still there in some way, how can I access it?

[Remilia]

Manufacturers use 8GB which translates to 8 billion bytes. Windows reads in GiB, which means every kB = 1024 bytes, as opposed to 1000. Which is where the discrepencies come from. Usually 100MB~ is reserved for the drive.

[Netherspark]

Huh.... yeah I've just noticed that every drive has the same descrepency

Never mind, I'm just an idiot.

[WskyDK]

Manufacturers use 8GB which translates to 8 billion bytes. Windows reads in GiB, which means every kB = 1024 bytes, as opposed to 1000. Which is where the discrepencies come from. Usually 100MB~ is reserved for the drive.

I'll be damned.
Learned something new