Published August 28th, 2007 edit replace rm!

The imperial units such as pounds, inches and feet have been receiving a fair about of criticisms and ridicule in the blogosphere recently (of course I can’t find the posts I’ve stumbled upon recently). Around learned people and in international crowds this is bound to happen fairly often. Of course the battle has been going on for centuries.

As someone who grew up in Denmark with the metric system yet also grew up making pancakes from recipes in the Joy of Cooking I am fairly used to both systems and would like to take a bit of a contrarian defense of Imperial Units..

Let me first state that I like both systems of units and both have their uses. Also contrary to the argumentation of many European’s you are not stupid if you don’t understand metric, nor the other way around.

So the big advantage of the metric system is that it is easy to convert say from centimeters to meters to kilometers by cutting or adding 0’s off the end of a number. There in lies it’s genius.

Many people also add that the metric system is based on real verifiable physical properties such as the distance travelled by light in an absolute vacuum during 1/299,792,458 of a second. I would like to say that this is about as useless and arbitrary in daily life that seriously, who cares? Scientists and engineers do of course, but in daily use no one else.

So I’d say conversion and international standards are the most important aspects of metric units. However the fact that all units are based of decimal multiples of each other in some form or the other, is also the cause of the largest usability problem with it.

The metric system was originally developed by scientists during the enlightenment, but became the political tool it is today as part of the French revolution, yes it was brought to you by the good folks who also brought you the guillotine. Thus it was imposed on people from above to better their lives. This is also what has happened every other country in the world except it appears the US, Liberia and Myanmar (metrics that is, not the guillotine):

While standardized differently various parts of the world the Imperial Units essentially evolved organically over thousands of years by people. While prior to standardization not very precise measures were possible, they were all based on real world reference points that gave you an idea of their uses.

Thus a foot is well the length of a human foot. Miles come from the latin word for thousand and basically means 1000 paces and goes back to the roman days. A cup, is well a cup. An inch is a thumb length.

Most of the old units are gone now, but the most useful ones are still with us. Why? Well because they reflect useful sizes in daily use. So if you take a moment and look at it from a usability dimension like most of us web application designers like to think we can do.

A cup or a foot or a pound might just be more usable during actual daily use. Lets think about it. For measuring the length of something smallish like a notebook 15 inches just seems easier to relate to than 38 cm. I’m sure a psychologist could explain it better.

When measuring a room feet just seems an easier unit to eyeball. I could eyeball meters but not as exactly as with feet. The keyword here is eyeballing. Anything that can be eyeballed more or less might be easier to use with imperial units.

Cups and pounds relate much better to real portion sizes in a traditional home kitchen. Almost all recipe’s call for a pound of meat as it’s a kind of natural portion amount of meat to cook with. The same with cups of liquid. It’s way more natural to use a cup of liquid as the base of a recipe than deciliters.

That is the beauty of the imperial system is that because they were evolved and not specified they are naturally easier for us to relate to. In other words for the uses they were originally designed they are more usable.

However the needs of engineers, scientists and 7th grade maths students are very different. It is obviously a lot easier when you are trying to understand or change the world to have a common frame of reference and easy conversions. For them the metric system is great.

Everyone says the US is not metric. What that means is that the US hasn’t invented a law yet to say that we’re metric. This is all it means. For all intents and purposes the Americans who need to be metric are metric. Scientist, engineers, big business and designers already metric.Why? Because it makes sense for them in their trades. Almost all grocery’s also have metric units listed on the packaging.

Why do ordinary people have to be forced into using metrics in their kitchen or measuring their living room prior to going to Ikea? The answer is they don’t. The metrification map

I linked to above shows pretty much a metric world. But what it doesn’t tell you is what people still use in daily use.

England is listed as being metric. That is a joke. Everyone in England thinks in pounds, stones (yes stones), miles and feet. Panama is listed as being metric since the 20s. But if you go to the meat counter in the super market and order “medio kilo de carne molida” you will receive blank stares (and possibly a “gringo loco” under the breath). They use pounds, inches etc just like the US.

Obviously there are lots of countries that are metric, such as Denmark, Germany and Franche. But even highly metric Denmark still has remnants of it’s evolved units that stubbornly refuses to die purely for reasons of usability. Recipe’s don’t talk about using 15 milliliter’s worth of sugar but 1 tablespoon.

I’m sure every country has still got their own traditionally evolved units in use in the markets, kitchen or even hidden in standardized portion size.

What about web developers. It’s generally recommended that we use a combination of evolved units such as em’s and points as it is designed to be usable and adaptive for humans. Pixel’s while more natural to us engineers are not quite as useful for our endusers with different screens, computers and vision.

By their very nature I am also guessing that evolved units such as feet and cups grew as people grew and became healthier over the centuries. And why not? As appetites grew the cup size grew, but the recipes stayed the same. It makes a lot of sense to measure your living space based on your actual foot size than some standardized version of a foot, as you are the one who is going to be living there.

So please, all I’m asking is less of the ridiculous flame war thats been going on the last century between metric and imperial. Both are good for their particular purposes.

Yes a generation trained to think metrically won’t normally have that much a problem dealing with it, but training is not the be all and end all of this. I’ve spent years programming in the rigid standardized world of Java, but I now prefer the far more flexible Ruby language as it’s more usable to me. I can relate to it better. Unit’s should be all about choosing the best tool for you for the task at hand.