You don't waste 5% of space, it's simply not there!
There is a SMALL amount of space reserved by the drive for remapping known bad sectors (for example Maxtor provide an utility to "fix" bad sectors - once completed you have a drive with no bad sectors, just a "rattle" when it gets to the remapped ones as it jumps to the end of the drive to fetch them from the reserved area).
When calculating memory sizes (e.g. RAM):-
1 KiloByte = 1024 Bytes
1 MegaByte = 1024 KiloBytes = 1,048,576 Bytes
1 GigaByte = 1024 MegaBytes = 1,073,741,824 Bytes
Hard drive manufacturers don't do this, though, and it works in their favour:-
1 KiloByte = 1000 Bytes
1 MegaByte = 1000 KiloBytes = 1,000,000 Bytes
1 GigaByte = 1000 MegaBytes = 1,000,000,000 Bytes
This means that the true capacity of a drive is only approx 93% of the capacity on the box.
Here's how to convert between the two:-
RAM MB -> HDD MB = multiply by 1.048576 (or multiply by 1.024 twice)
HDD MB -> RAM MB = divide by 1.048576 (or divide by 1.024 twice)
RAM GB -> HDD GB = multiply by 1.073741824 (or multiply by 1.024 three times)
HDD GB -> RAM GB = divide by 1.073741824 (or divide by 1.024 three times)
For a rough HDD GB -> RAM GB conversion, divide by 1.07
I read about this years ago, but just to confirm it I've just found much the same info at:-
http://www.maximumpc...2001-08-10.html