Hi,

Recently I bought new HD, WD WD5000AAKS. It's capacity is 500GB, but when I open properties in my computer it shows 465GB. What happened with 35GB? I noticed this generally with HD's. My other HD which has 200GB capacity, actually has 186GB. Can somebody explain me why HD does not have capacity as manufacturer claims?

Cheers

Hard drives have been sold like this for a very long time. They sell their hard drives as 1 gigabyte = 1000000000 bytes, whereas you were expecting 1073741824 bytes in a GB.

So your hard drive is 500 * (1000000000/1073741824) GB, or roughly 465GB.

Here's a quick list of "advertized" drive capacities, versus "real" GBs (no decimals):

20 GB: 18 GB
40 GB: 37 GB
80 GB: 74 GB
160 GB: 149 GB
200 GB: 186 GB
250 GB: 232 GB
320 GB: 298 GB
500 GB: 465 GB
640 GB: 596 GB
750 GB: 698 GB
1000 GB: 931 GB

It's actually a misnomer in computer terms.

Kilo (10^3), Mega (10^6), Giga (10^9), Tera (10^12) - these all describe powers of 10.

Kibi (2^10), Mebi (2^20), Gibi (2^30), Tebi (2^40) - these all describe powers of 2.

These terms are often mixed up. In any piece of software, things are measured in the powers of 2 (computers are binary systems afterall). In hard drive manufacturing, they use the powers of 10. crahak already gave the conversion factors above, but this is the reason behind it all.

Well, that's the "new names" some people use to differentiate. But seriously, go in a computer shop, and ask them for a 500 gibibyte hard drive, or talk with a co-worker about kibibytes, and you're gonna get some weird looks. Similarly, some hardware sold goes by powers of 2 too like RAM (when you get 2GB of RAM, it's 2048MB, not 2000MB). In practice, nobody actually uses those fancy terms, even though we're really misusing SI prefixes... I just tried to explain it the easy way, without involving weird words

You're still completely right

OK, thanks for answers guys. I understand now.

Cheers

to sum it up,
500.000.000.000 bytes is what you buy,
465,7 x 1024 x1024 x1024 bytes is what Windows reports as GigaBytes, cause 1Kilobyte is 1024 bytes (10^2), etc.
Which is the same if you do the math.

It reminds me of an old joke about two programmers:

- how's your new job?
- fine, fine...
- how's the boss treating you?
- fine, fine...
- what does he pay you?
- 1000 $
- that bastard! Couldn't he round it up to nice even number like 1024 ?!



GL