Why is the effective hard drive size lower than the actual size?
For example, I have a 250 GB hard drive and when I add up all the partitions (and there are no hidden partitions), it comes out to 232 GB. I know that this is normal, but I was curious as to why, so I googled around a bit and have came across two theories.
One said this happens because the hard drive manufacturers use 103 to define a kilobyte (1000 bytes) while windows uses 210 (1024 bytes).
The other theory said that
1 GB = 1024 MB = 1024 * 1024 KB.
1024 * 1024 * 232 = 243,269,632 ~= 250GB.
Which theory is true? Or is there a different reason that is the correct reason?