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Does size really matter MB versus MiB

Author: ITS

Posted on Jun 8, 2011

Category: Geek Speak , General Interest

You've probably heard all about megabytes and gigabytes, but have you heard about mebibytes and gibibytes? Most of the time, when we talk about how much storage space is available on an electronic device we speak about the number of gigabytes available. The problem is, the prefix "giga" means very different things depending on whether you're talking about electronics or anything else - and this is a bad thing when you want things to be easier to understand.

Consider this: when you talk about a "megabyte", most people would actually think something along the lines of "one million bytes". For scientists and engineers not dealing with electronics, this is correct; "mega" means "one million", or 106, of something. But for computers, "mega" is actually "one million forty-eight thousand five hundred seventy-six", or 220. If you've ever noticed that your hard drive doesn't have as much space as the specifications claim, this is why; hard drive manufacturers interpret "500 gigabytes" to mean "500 billion bytes" ("giga" means "one billion of something") and give you exactly that much space. However, when your computer reads the drive, they start thinking in computer terms and say you actually have about 465 gigabytes. These numbers are actually exactly the same, just interpreted differently, which leads to a lot of confusion. The difference between what you think you should get and what you actually have only gets much larger as you get larger storage capacities.

ThinkingThe solution, put forward by the International Electrotechnical Commission in 2000, was to stop using these names and create new ones. This is their list of new terms for the ones you probably already know:

•    kilobyte (kB) -> kibibyte (kiB)

•    megabyte (MB) -> mebibyte (MiB)

•    gigabyte (GB) -> gibibyte (GiB)

•    terrabyte (TB) -> tebibyte (TiB)

There are more, but they aren't commonly used yet. For most people, a terrabyte is still an incredibly large amount of storage. It will probably be a long time before you see these used everywhere since the computer industry is very slow to change such well-established things. Look at the mouse, for example: it has been in use, essentially unchanged except for becoming much more comfortable and better looking, since the early 1970's. The keyboard is even older. More people are starting to use these new terms for storage space, and now you will know exactly what is meant when you hear about your "512 MiB" quota on UNB File Drop.