Do you know the difference?
Yes, one is lowercase and one is uppercase.
But think about them in terms of symbols used with numbers.
m stands for the unit metre.
M stands for the prefix mega as in megabyte.
In my line of work, I see a lot of business and technical documents. And I’m surprised how often people misuse units of measure and their symbols.
If you work in a technical field, you really have no excuse for not knowing how to specify units of measure properly.
Try this quick quiz
Can you see anything wrong with these examples?
- 10 Kg
- 100 kms
- 1000 Mbps
- 1000 Mb per second
If you can’t see anything wrong with them, read on …
If you think they’re all wrong, then you’re right.
Going through them in turn:
- There should be a space between the number and symbol. And msec is not the symbol for millisecond.
- The symbol for kilogram doesn’t have a capital k.
- Symbols are always singular. You don’t add s to make them plural.
- per isn’t shortened to p (regardless of what hardware and software vendors put in their catalogues and on their websites).
- Don’t mix symbols (like Mb) and units (like seconds) in the same expression.
The correct forms of the examples are:
- 1 ms
- 10 kg
- 100 km
- 1000 Mb/s
- 1000 megabits per second
Even though people may understand the erroneous forms, there are standards for units and symbols, and conventions for their use. International standards and conventions at that!
So too bad if you disagree with my corrections.
The International System of Units
In Australia, most units of measure follow the convention of the International System of Units (which is symbolised as SI from the French, Système International d’Unitès).
It’s all about the way to specify metres and seconds and other units of measure, as well as the prefixes, symbols and derived units to use with them.
And the system of quantities used with the SI units is set out in ISO 80000, parts 1 to 14, making SI units the same everywhere in the world.
The problem is we’re not taught how to specify these things correctly. I certainly don’t remember learning the convention in science or maths at school. And I don’t remember anyone ever correcting me during all of my years in the workforce.
Another problem is that incorrect use becomes copied and popularised … but that doesn’t make it correct.
So, no more excuses.
Here are the main rules for specifying units of measure:
Remember, no more excuses!