Wednesday, August 4, 2021

The Case Against the Metric System


It’s easy to argue the merits of the metric system—its ubiquity in the developed world, the ease and elegance of doing calculations with it, etc.—but this is not very interesting. Meanwhile, proponents of the metric system (aka “metricites”) have often struck me as very secure in their position, to the point of smugness. My dad—a gruff, dyed-in-the-wool engineer—was this way, and after decades of sucking up to him, trying to gain his approval, I became disgusted with myself and looked for ways to occasionally nettle, annoy, and provoke him instead. Toward this end, I discovered that praising the imperial system of measure worked great. The withering, disgusted look he gave me, bordering on anger, was priceless. Ever since, I’ve been pondering the advantages of the imperial system and planning a more widespread assault on the metric. Here it is.

(A semantic note: in this country, the measurement system developed by the British, generally referred to as the imperial system, often goes by the term “US customary system.” I’ll use the term “customary” in this sense throughout this post.)

Leadership vs. subservience

Because some metricites will write off the customary system purely because most of the developed world has, I’ll start there. The prevalence of the metric system cannot be denied: look at this map of who uses what system.

Look at how many nations are on the metric system! Could this many people be wrong? Sure! Keep in mind that almost 3 billion people worldwide waste their time, ruin their privacy, and compromise their emotional health by using Facebook. And when they do, the vast majority use a terribly antiquated and inefficient keyboard layout. Don’t look to your fellow man for the best way to live a perfect life.

Meanwhile, consider that the map shown above would probably bear striking resemblance to a map of where you can get a good taqueria-style burrito, and what nation creates the best movies, software, and rap music. The US is not traditionally a follower on the world stage. We’re probably much of the reason English is the lingua franca of world trade, and our dollar is also the foremost global currency. Don’t look at that turquoise coloration and think “outlier.” Think “leader” (or at least “leadership potential” since, admittedly, the rest of the world doesn’t always follow us).


This is an easy one. The fact of Celsius having zero as the freezing point of water and 100 as its boiling point is admittedly cute, but not actually very useful. My brother Bryan, solicited for comment on this debate since he’s an engineering sort but also an expansive thinker, has eloquently pointed out:

As elegant as the Celsius scale is, I find it’s a bit crude for actual measurement of the human condition. Most of our experience takes place between really cold and really hot, which is to say from well below the freezing point of water to a bit above 100 degrees Fahrenheit. Much above 100 F, you’re kind of toast anyway; once your flesh starts burning it doesn’t really matter what the number actually is. It’ll never get anywhere near 100 Celsius, so that part of the scale [38 to 100] is just wasted. And if you want to talk about it being really cold with C, you have to use negative numbers, which is kind of awkward, especially if you want to compare temperatures.

Couldn’t have said it better myself. Meanwhile, the other obvious benefit of Fahrenheit is that the units are smaller so it’s more precise.


No matter how handy calculating with base-10 may be, there’s no arguing that 60 mph—that is, a mile a minute—is a really handy mnemonic, since it’s roughly the speed we drive on the highway (the >60 mph speed limit being offset by roadside stops, etc.). If our destination is 300 miles away, it’ll take about 300 minutes. The kilometer cannot offer any similar trick. And since the typical speed limit on a city street is 35 and on a residential street it’s 25, we can estimate the time for a non-highway trip by just doubling the miles … so a five-mile drive across town will take roughly ten minutes. (If your community is more congested than this, leave your car at home and use your bike. In fact, do that anyway.)

Another benefit to miles is the word “mileage.” This is a very useful word, both literally and figuratively (e.g., “Your mileage may vary”). There is no equivalent in the metric system: “kilometerage” is not a word and if it were, it would be a dumb word used by nobody ever. Same with the word “milestone.”


As with temperature, the larger weight units in the metric system make it less precise, a kilogram being 2.205 pounds. But the lack of precision isn’t the only problem; it’s also the case that since a majority of humans would like to lose weight, this larger unit is demoralizing. Imagine eating right and foregoing fattening snacks for a whole week and then having to express your weight loss with a fraction: “Oh, boy, a lost a whole half-kilogram!” That kind of discouraging scale (no pun intended) is the last thing America needs.

Liquid measure

Actually, this is one area where Americans do dabble in the metric system: although we measure most liquids (fuel, beverages) with customary units (gallon, pint), there’s one product that’s sold in metric units: wine. How fitting, since so many wine lovers are annoying and pretentious. Humbler, more down-to-earth Americans drink beer, which is of course measured in ounces (excepting some small and/or lazy overseas breweries that don’t bottle or label their product specially for the American market).

Why does it matter that wine is sold in metric units? It’s because Americans have no sense of milliliters, so we can’t keep ourselves honest when drinking wine. It’s hard to develop a sense of volume with an ungainly basis like the liter, as it’s too large, and nobody ever uses deciliters—they’re too small (less than half a cup)—and there’s nothing in between a liter and a deciliter. With beer, you can keep track pretty easily: whatever vessel you pour that can or bottle of beer into, it’s a known entity: 12 ounces, one drink. From a temperance perspective, the 750-ml wine bottle is a black box: the servings vary with your glass and how much you fill it; the milliliters are like Monopoly money; you just pour and pour, and you wake up hung over and overweight. This is what happens when Americans indulge the metric system.

Another benefit to the customary system: when you go out for a beer, you can say to your pal, “Shall we go grab a pint?” This has a nice ring to it. What would you say in France? Perhaps “Allons-nous prendre un demi-litre?” (literally, “Shall we grab half a liter?”) That sounds terrible—how do you grab half of something? And “Allons-nous prendre un litre?” sounds like you have a drinking problem—I mean, drinking beer by the liter? Yes, I know the French wouldn’t actually say this; they’d say, “Allons-nous boire un verre de vin?” (literally, “Shall we grab a glass of wine?”). I rest my case.

Air pressure

When it comes to inflation, you can’t beat the pounds-per-square-inch (PSI) unit, because the proper inflation for a road bike tyre is a nice, round 100; for a commuter bike it’s a nice, round 50; and for a mountain bike it’s a nice, round 25. What are the metric equivalents? That would be 6.895, 3.447, and 1.724 BAR, respectively. Nothing nice or round about that. (Apparently some Europeans prefer kilopascals, which is just fricking goofy. Imagine pumping your bike tires up to 690 kPa, or 690 of anything, for that matter … I’d be afraid!)

Meanwhile, the giant size of the BAR presents an obstacle to precision. I can input my weight, tire width, and riding style into a handy-dandy mountain bike tire pressure calculator and it gives me a nice precise inflation number: in my case 25 PSI for the rear tire. Since the calculator is trying to be metric-friendly it also gives me 1.8 BAR … but that’s not right—that’s actually 26 PSI, which could be the difference between great handling and merely good. To be sufficiently precise we have to go into the hundredths, with 1.72 BAR, and who can remember that?

(Arguably air pressure measurement isn’t that important, but it’s simpler than some of the next few categories.)


As detailed here, much of American industry does use the metric system (which, I hasten to point out, is no reason everyday Americans need to do so in their personal lives; after all, it’s not like web developers speak in HTML at the dinner table). One standout is the construction industry, and for good reason. As my brother Bryan explains:

Using inches is really handy for doing the mental arithmetic associated with carpentry. When a carpenter uses inches, he’ll keep track of the bit smaller than an inch using fractions, with as much resolution as is necessary for the application at hand. For example, if he needs to cut a two-by-four to use as a brace while framing a house, he may only need to cut it to within an inch. If he’s cutting a piece to be used as part of an internal structure for something, he may need it to be accurate to half an inch. If it’s a finishing piece, he may want it to be much more accurate, say a sixteenth of an inch. Using fractions, you can decide before you start cutting what units you’ll use—half inches, quarter inches, and so on. Each division is twice as precise. It’s easy to adjust the accuracy of your calculations as you go, too. For example, if you find that ¼ isn’t accurate enough, say you want slightly more than a ¼ inch, you just go to eighths of an inch: ¼ is 2/8, so a smidgen more than that is 3/8 (three of them instead of two), and so on. The tape measure shows these gradations elegantly with longer and shorter ticks, making it easy to visualize these fractions as well. So in ‘merican, you have all these units to choose from that we’re all familiar with and that are easy to convert among: 1/2, 1/4, 1/8, 1/16, and even 1/32. In metric all you have are centimeters and millimeters, which are significantly different in size, so if a centimeter isn’t enough resolution, you have to jump all the way to millimeters and keep track of a bunch of them.

Another thing that carpenters often must do is find the midpoint of a piece of lumber or whatever. So if a carpenter’s board is 21-½ inches long, he can calculate half of that easily: 21 divided by 2 is 10-½" for the whole part, plus ½ divided by 2 which is ¼ for the rest. It’s easy to add the ½ and ¼, since ½ is 2/4, making ¾” for the fractional bit and thus 10-¾” for the whole thing. Dividing that in two is 5 & 3/8”, which is easy to compute since dividing a fraction in two is just doubling the denominator. I feel like doing this kind of mental arithmetic keeps us closer to the numbers and to their scale, while just plugging numbers into your phone and tracking them to four significant digits makes you lose touch with reality.

Yeah, exactly! This guy knows what he’s talking about ... he even holds a math degree!


Okay, that was a lot of math so this next category will be simpler: guns & ammo. This is another area where Americans are dabbling in the metric system. Traditionally, firearms were described in customary units, such as the .45 Colt, the .308 Winchester, and the .30-06 Springfield (all of which numbers indicated the bullet diameter in inches). These are all old school, and American. Now, your more worldly guns, like the Uzi and the Glock, use the metric system with their 9-millimeter round. Which is better? From a practical standpoint there can be no difference because the utility of a firearm, for civilians, is essentially zero. To split hairs we’ll have to consider the matter culturally. In that vein, I have to admit that the modern automatic weapons heralded in rap songs sound cooler and more sophisticated (e.g., “slapped a clip in my nine”) than older American standards—and that’s exactly why the metric system is a bad choice. America has a huge gun problem and the last thing we need is to be glamorizing firearms of any kind. If the .45 Colt and John Wayne seem anachronistic, that’s good … because guns are, too. The wild west days are over and (to paraphrase Ice-T) your best weapon now is your mind.

Shoe sizing

It’s pretty normal when thinking about the metric system to lump the European shoe sizing standard into it. Thus Americans are tempted to think that European shoe sizing, with its smaller units, is both a) metric, and b) more precise. In actuality, European sizing is a disaster. As explained here, this sizing is based on the “length of the last, expressed in Paris points,” which are 2/3 of a centimeter. There is absolutely nothing elegant or sensible about this, and even with this smaller unit of measure I’ve bought cycling shoes in half sizes (e.g., 45.5). Any perceived benefit of greater shoe sizing precision is an illusion, because with shoes you simply must try them on as the fit will vary widely across manufacturers (shoe size expressing only one dimension to begin with).

So why is this a mark against the metric system? Because Americans who have been brainwashed that the metric system is superior will automatically assume that European sizing is a) metric, and thus b) better. If Americans stuck to their guns (an unfortunate turn of phrase, I’ll admit) about our customary units, we’d probably kick this silly European shoe sizing basis to the curb as well. At least our size 12 shoe is approximately 12 inches long … give me one good reason why 45 makes more sense.

Let’s put this base-10 thing to rest

Naturally the metricites among my readership are all saying, “But wait, none of the above matters because base-10, base-10, base-10! Elegant calculations! Engineering! Stuff that matters!” Even if I indulge this by pretending that the industrial world is more important than the quotidian doings of your average joe, I take issue with base-10 being obviously better. Why? Because the base-10 system lacks sub-multiples. To explain this, I will quote from my friend Peter’s son’s friend, a recent high school grad named Kellen Sisco (who may or may not be ready for the worldwide fame he’s about to achieve through this blog). Kellen, in an anti-metric essay he decided to write (totally unconnected to this post, by the way), explains:

In base ten, there are two sub-multiples: 2 and 5, and these are both prime, inconvenient numbers. Now, contrarily, base twelve is good, as there are eight sub-multiples: 2, 3, 4 (which divides by 2), and 6 (which divides by 2 and 3). So, at least four times as many sums in base twelve will [yield] convenient numbers. Base 24 has 19 sub-multiples! Number 16 is a particularly liked number amongst mathematicians because it is good for halving and doubling. As one can see; number 10 is not a distinctly good number; numbers 12, 16, 24, and 60 are considerably better numbers.

Now, I don’t expect you to take this young man’s word for it that mathematicians like the number 16, or that 12, 24, and 60 are better than 10; instead, I’ll give you some real world examples. Consider mathematicians … what do they even do and why do we even care? Well, you like money, don’t you? And what math is lucrative, besides the boring engineering that goes into, say, building bridges? Answer: the Internet. Mathematicians do crazy-ass stuff like string theory which you assume is useless until they suddenly solve some Internet routing thing and become gazillionaires, etc. And I’m here to tell you, Internet engineers just dig hexadecimal, which is base-16, just like Kellin said. A classic dot-com interview question, when hiring engineers, is a pop quiz on network subnetting, which requires the kind of in-your-head division I described above in the construction example; it’s fractions, not getting out your phone and calculating to several decimal places. So beloved is hexadecimal among engineers, I had a boss who balanced his checkbook with it! Sometimes network guys will use octal (for arcane reasons), and when constrained by electrical engineering requirements around on/off (i.e., 1 or 0) they’ll use binary, but they don’t tend to use decimal unless they’re pressed into financial projections (the least fun part of the job).

And what about 12, 24, and 60? Well, it’s no coincidence we use those to describe time, whether we appreciate all the sub-multiples involved or not. We can say “Meet me at quarter past nine” and that’s really easy to grasp (and to visualize, clocks being as elegant as they are). With a base-10 time system we would all be totally screwed. Decimal time has a 10-hour day, so the units are impossibly huge: the minute is 1.44 times the size of ours, and the hour 2.4 times the size, so you’d always have to use decimals since you wouldn’t have handy fractions to play with. Just look at this preposterous base-10 clock:

I’ve tried to figure out how to express 9:15 a.m. in a base-10 time system, and my head exploded—and I’m no slouch at math (being well versed in binary, octal, and hex, and being nerdy enough to blog about daylight saving time, leap years, and leap seconds). If my head explodes contemplating base-10 time, surely billions of heads would explode worldwide if we tried to adopt it. And of course nobody has (except, briefly, the French, who abandoned it after less than a year … ‘nuff said).

Since we thus acknowledge base-10 is not necessarily superior, I think we can agree the metric system doesn’t automatically get a huge benefit from it. So to the STEM types promoting the metric system on this basis, I have this to say: you talk dog farts.

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