This blog post is heavily inspired by jan Misali's excellent video essay on the topic.

A perennial topic on the internet is that America should go completely metric. It's actually something that people get weirdly heated about, and something that some Americans get weirdly defensive about. Here in Canada, we use the metric and the imperial systems depending on the use case, one of the few countries in the world to do so. I used to feel that we should also try to get rid of the imperial system, but lately, I've started to feel like there's real flaws that come with metrication. This isn't a hit piece on the metric system, but I want to explain why I don't buy into metric supremacy.

The Metric System Is Unwieldy

The great promise of metrication is that having a single system to measure everything is convenient, especially when you need to compare, say, the weights of different objects. This is true, but it comes at the cost of ease and elegance. Under the metric system, length is measured in metres, or units that are metres multiplied or divided by powers of 10 (e.g. millimetres). Historically, the metre was defined as being 1/10000000 of the shortest distance from the North Pole to the equator passing through Paris. Later on, it was redefined in terms of the wavelength of Krypton atoms, and then once more redefined in 2019 to be in terms of time and the speed of light. Either way, the length of the metre has been essentially the same outside of extremely precise measurements. This is great for if you need to measure the distance between things, because that's what the metre was created for. The problem is when you try to use it for more than that.

I went to Italy a few months ago, and when my cousin asked me my height (I'm quite tall by my family's standards), I could only give it in feet and inches. In Europe, height is measured in centimetres, so they were confused about how tall I really was. Now, this is obviously subjective, but having to give a triple digit number to state my height feels a bit awkward to me. More than that, it just feels like an unnatural way to think about height. Why base my height on the distance between the North Pole and the equator? For that matter, why should I base it on the wavelength of Krypton atoms or universal constants? A much more intuitive way to think about height is to measure it based on human features, such as feet.

Again, I get that this is all subjective, and Europeans probably don't feel that measuring height in feet is natural. Still, I feel like that's because of cultural conditioning on their part instead of metric actually feeling natural here. Another example where the metric system fails is in measuring font size. The standard unit for fonts is the point, which is defined as being 1/72 of an inch. I don't care how European you are, you don't ask for fonts to be 4.2336mm wide, you ask for them to be 12 points wide. Trying to use the same measurement system for fonts, people, and large distances is ridiculous because there's never a situation where you actually need to compare them with each other. Despite the inconvenience of having multiple systems, it feels a lot more natural than just having one.

But What If I Don't Have a Calculator?

The metric system is great if you need to change units without changing the quantity of whatever it is that's being measured, since you just need to multiply or divide by a factor of 10. The problem is when you need to actually divide the quantity and you don't have a calculator on hand, which was everyday reality for everybody up until 15 years ago. This is where the imperial system actually kinda rocks. Take my previous example about how height is given in feet and inches. There's 12 inches in a foot, and 12 is easily divisible by 2, 3, 4, and 6. Dividing by 5, 8, and 10 only results in one decimal point, which isn't too hard for most people if they really apply themselves. Dividing by 9 gives an infinite number of decimal points, but if you think of it as a fraction to be reduced, it's not that hard to see that the answer is 4/3. The only digit that's hard to divide 12 by is 7. Now compare that to 10. This is only easily divisible by 2 and 5, and reasonably easy to divide by 3 and 4. That leaves 6, 7, 8, and 9 as hard digits to divide with (math types might disagree with that, but the average person is REALLY bad at mental division). If you're in a situation where you have to quickly divide in your head, feet is better than metres.

Nobody Uses Imperial When Metric Is Better

Despite what some people may say, Americans absolutely do use the metric system. Like, high school students don't learn about Poundals in physics class, they learn about Newtons. The only real difference is that they (and to a degree us up in Canada) use imperial in situations where it doesn't actually matter. A pretty common counter-example is NASA's Mars Climate Orbiter, which crashed because the software used imperial units when the engineers were expecting the output to be in metric. What this ignores is that the problem code was outsourced to Lockheed Martin rather than done in-house. NASA requires all code to use metric, but Lockheed Martin didn't follow the specifications. By NASA's own admission, the problem was that their checks and balances failed to catch the error, not that the code actually contained an error.

Imperial Is Important, Sometimes

Even though the metric system is the standard for some purposes, there's other circumstances where the imperial system is internationally used. For example, shipping containers are always measured in feet (not cubic feet, oddly enough). If you want to create a metric replacement, you would have to violate the ISO standard and find a different country willing to do the same. For what? Because you're obsessed with a system of measurement? That's ridiculous, just use the imperial system if it works well. That brings me to my final point:

This Doesn't Really Matter

There's times where one system is better than the other, but it's never really a huge deal. It's not like a measurement system isn't going to measure things in a consistent way. Just use whatever system is more convenient, no need to overthink it, much less advocate for a radical overhaul of how we measure things.