MB vs. Mb

Oh dear! Bother bother! What has happened to ‘standards’ in the IT industry? Back around the late 90s it was a professional standard that an upper-case “B” meant bytes and a lower-case “b” indicated bits.

It is so damned obvious really. Bits are ‘smaller’ than bytes so use a little “b” for bits, and use a big “B” for bytes because they are bigger than bits (it takes eight bits to make a byte).

So  . . .  1MB would is million bytes and 1Mb is one million bits.

Could anything me more obvious or simple? This is sheer brilliance in technical notation shorthand.

Back in the 90s it was very rare to find a “professional” IT writer that did not adhere to this shorthand notation. Whether you were reading an article in an industry magazine or absorbing a reference manual you could be reasonably sure that if you came across 200Mb it meant 200 megabits and not 200 megabytes.

If you lookup “MB” in Wikipedia you will find this entry there.


But now, sadly, it is becoming common to find someone write 7Mb for the size of a file when it should have been 7MB—after all, who refers to a file size in bits? When I read 7Mb I automatically read it as “seven million kilo-bits”, but in this case the author obviously meant “seven million kilo-bytes” because nobody refers to the size of a stored computer file using “bits”.

And when you see JB Hi Fi, Office Works, or Harvey Norman advertising 1Tb hard disks I wonder to myself who would buy one of those? These days who wants a 125 gigabyte hard disk? Because 125 gigabytes is what 1Tb is (1 million bits/8 bits to the byte). What they meant to put in the advertisement was a 1TB hard disk meaning 1 terabyte.

What we need is an IT industry Style Guide that we can all refer to. I wonder if such a document exists? That might be my next research exercise . . . try and dig out an IT industry writing guide or Manual of Style. If any of my eight or so regular readers happens to know of such a guide then please post a suitable comment pointing me to it so I can check it out.