Kibibytes and Mebibytes

19 03 2009

Whilst searching for something else, I stumbled across the use of the prefix “kibi-“ for the quantity 1,024 (i.e. 210), with this standing for “kilobinary” and having a corresponding symbol Ki.

For example, this leads to the term kibibyte for 1,024 bytes, kibibit for 1,024 bits, 4 KiB to indicate 4,096 bytes etc.

Apparently, as much as ten years ago the IEC started adopting a whole set of such “binary prefixes” to parallel the normal decimal SI prefixes of “kilo-“, “mega-“, “giga-” etc.

So as well as “kibi-“, we also have the prefixes “mebi-” (220), “gibi-” (230) and so forth, all the way up to “yobi-” (280).

For further details, see (for example):

I’m very surprised to have not come across any of this before, but I guess you learn something every day!

It all seems like a great idea for clearing up the ambiguity in the use of the normal SI prefixes when dealing with binary stuff (e.g. whether someone saying “megabyte” means 1,000,000 bytes or 1,024 x 1,024 bytes).

Some of the names don’t exactly trip off the tongue, and gave me the giggles at first, but that’s probably just from being unfamiliar.

I imagine it’s very hit-and-miss to get something like this into common usage, but I’d have thought that plenty of geeks would have latched onto these terms by now. At any rate, I’d like to think that Maurice Moss regularly puts these prefixes to good use.

Does anyone actually use these prefixes in real life or are they just an idea that has never gained any traction? Am I alone in having not heard of them or did this pass everybody by?

Maybe it’s time to start spreading the word and using these terms more widely…

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