The bigger the drive gets the bigger the gap between GB and GiB becomes. You see, the drive capacities are listed as 1 KB = 1000 Bytes, 1 MB = 1000 KB etc. The OS (whether computer or console) uses 1 KB = 1024 Bytes. 1 MB = 1024 KB etc. So the bigger the drive gets, the bigger the difference between the OS scale and the drive makers scale. It has been propsed to rename the 1024 units to KiB, MiB etc but only Linux has actually done this, and drive makers certainly don't want to use it since they use the difference to make drives seem bigger than they really are.

hardware arquitecture 101.
the filesystem uses a table, for every bit on the HDD. that uses space.
when you quick format, that what it's delete, bigger HDD, more GB you loose.

File systems 101.

http://en.wikipedia.org/wiki/File_system

Just be happy its not using FAT.

When did 1KB become 1000 Bytes.  Did I miss a memo or something, but in electronics never has 1KB been equal to 1000B.

The GB thing is a little tricky to me. This is how i understand it. A computer 1GB seems to be larger than a "actual" 1GB. (Like 2GB of ram in my PC is actually 2.095 GB of ram.) I think the 120 GB HDD is referring to "actual" GB while 113 GB is in reference to the computer oversize GB.

 P.S I see someone else above explain it better than I have.

So are you saying this size listed on an HDD doesn't actually use an even 2^n file size?

EDIT:  Nevermind, I just went through this crap on Wikipedia.  So why would we change the naming nomiclature to GiB to compensate for an incorrect usage of units in hard drives.  So this means your actual data size is -48576B/GB or -24kB/GB.  This would automatically lose 2.88 real GB on a 120 fake GB HDD.  Well with the increase in HDD storage space, there may be some complaints as the listed size is missng 24GB/TB.

EDIT2: oops, bad math, on a 120GB HDD you lose 2.8125GB or 2880kB.

My '20gb' hard drive only had 12 gbs available. That's probably the same issue.

Thanks for all your insights folks.
I understand it a bit better now.
I have the 20 gig 3 years so 90 should do me for about 20 years lol.

Haha, it's no 'issue'! It's just that computer OS's uses binary for example they see 1GB = 1024KB, where at the same time all storage formats uses the Système international so all storage formats see 1GB = 1000KB.

My 120gb ps3 had 111gb or 109gb when I checked, right now I have 80gigs left.. I still feel like 120gb may not be enough..