When is 500GB not 500GB

Today I bought an external hard drive, mainly to use a picture backup, however once it was plugged in I noticed the following:
On the box an nice big red label, 500GB
Plugged in and get 499,983,024,128 Bytes followed by a capacity of, 465GB.
So is the drive 500GB or not. Is counting the bytes and then converting them to GB, which is not the capacity GB a little fraudulent. I wanted a 500GB Capacity and not a 465GB.
Matt
On the box an nice big red label, 500GB
Plugged in and get 499,983,024,128 Bytes followed by a capacity of, 465GB.
So is the drive 500GB or not. Is counting the bytes and then converting them to GB, which is not the capacity GB a little fraudulent. I wanted a 500GB Capacity and not a 465GB.
Matt