January 17, 2007

How much is a Giga?

Posted in Computers, Life at 1:10 pm by pmatos

HD Photo
I got a new toy latest November which as been extremelly useful.

However, I bought a 120Gb drive and when I got it, system reported about 110. Well, what happened?
In WesternDigital site they teach that

One gigabyte (GB) = one billion bytes.

Which means that for each gigabyte you buy from them, you lose 73741824 bytes, which is a bit more than 70Mb. Which is not much when you buy 1Gb but when you buy (like we currently do) 120Gb (or in cases of huge drives with 750Gb), you lose 8Gb!

Why? Why? Whyyyyyyyyyyyyyyyyy?!?



  1. Andre Luis said,

    One word: Marketing. :) It’s better to say 120GB than 112GB…

    The more tech-savvy users have to bear this in mind when they/we shop for hard drives. Storage device brands always think 1Giga=1000Mega. I just bought an Iomega 500GB and was already prepared for the cutoff, so there was no surprise.

  2. AFAIK, the problem is an inconsistency in using “GB” as a short both for “gigabyte” (which, as per SI using, is 1000×1000×1000 bytes — which Western Digital appears to teach well) and for “gibibyte” (1024×1024×1024 — which has a more correct symbol: GiB).

    If you are able to check, your 120GB hard drive still has what is not (that) far from bytes, and your OS says that number as 110~111GiB (but uses the GB symbol).

  3. Err, a “xB” has always (even since the MB times) been a one and a lot of zeros, in a lot of computer nomenclature, and even more in the hard-disk description, so 120GB “hard-disk” will alway be proper “111.75GiB”.

    Then, depending on the file system used, you’ll also loose a couple dozen more GiB, and that’s why “some” people with “certain” Operating Systems complain that his 120GB hard disk is only shown as a 90GB hard disk. :D

    (come on, what is 8GB in a 120GB hard disk?) :P

  4. pmatos said,

    Curious, I had never heard about *iB units… :-) Nice, I know now!

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