Ask HN: Why it is hard for US to move to metric system?
The fact that it is almost impossible to move to the metric system in US is strange. It is even stranger because of the big influence of immigration (every other part of the world use metric system) so I wonder why it is that hard?
189 comments
[ 0.22 ms ] story [ 229 ms ] threadHowever, I also think to some extent the US is changing, it's just happening very slowly.
I think a lot of commerce and travel is part of it. If you buy something designed and produced overseas, and you have to get parts for it, it will be in metric. Lots of imports are in metric, if you travel you deal with metric, and so forth and so on. I've been to US hospitals that only keep charts and communicate in metric as a matter of policy, etc.
The only remaining things in the US that are hard for me to intuitively deal with are speed when driving and temperature, and temperature I'm starting to kind of fuzzily intuit.
It's much simpler than that, and has nothing to do with people; it's the range between freezing water and boiling water, and that's it.
If 24" monitor sounds ok and you have no idea how big 61cm display is then it's safe to say we're also creatures of habbit and it's nothing specific to US.
There was a push toward adopting the metric system under Carter but since then the right wingers have been largely in control of the political discourse.
Source: am American.
The US gallon is the same as the now-defunct English 'wine gallon'. The US mile was similarly the same as the UK statute mile, until it was indirectly redefined in terms of the metric metre in 1893. So at least the two examples given are not homegrown.
We are an incredibly stupid country, because many of us actively devalue education, or otherwise denigrate people who learn. The requirements for teaching and education varies wildly state to state, including many states that basically have NO requirements for teachers, and we have actual, real, paper textbooks purchased by southern school systems that teach slavery as "not that bad"
In scenarios where metric is actually needed or appropriate nobody has any trouble using metric. Every kid has learned it in school for decades.
This is the key point. What people asking this question often miss is that the US is actually a dual system country. Metric is quite common anywhere it is valuable to use! So the places it isn't used are mostly the places it isn't so useful, or at least where the transition cost is very high.
[1] https://en.wikipedia.org/wiki/Mars_Climate_Orbiter#Cause_of_...
But I find day2day use of measurements in inch/ft, e.g. in home renovation and architecture, way way easier than metric system.
I think it's the other way around. The adoption of the metric system was an ideological program from a very specific time. An enlightenment belief in a supreme rational order of things, military science transferred into the real world.
Metric system is cool, but it's not "better". Personally, I think it's worse and awkward for many use cases.
How many feet is 74 inches? How many meters is 1234cm?
(How long did it take for you to do that math in each case?)
So easy. So clean.
1234cm is the dumbest measurement ever. Once you find yourself working with those, you are either a scientist or you have adapted to the machine rather than have the machine adapt to you.
It would still take you longer in your head to come up with 6ft 2inches (which is the wrong answer, btw, the right answer is 6.167 ft.), than it would to come up with 1.234 meters.
> Once you find yourself working with those, you are either a scientist or you have adapted to the machine rather than have the machine adapt to you.
This is a super weird comment for a programming-centric forum.
Also - weight and volume relations have mostly scientific relevance. Not joe schmoe putting up out some drywall, or proportion door and window sizes.
It's not that you can't use metric system. It's just worse for a lot of day2day.
It is ALL DECIMAL, which is the point.
It is in the "English" system that you have to deal with the fractions: the board is 8 feet 1 and 23/32 inches long. Now how long will it be when you cut off 5 3/8 inches from that?
If you can't more quickly subtract 137mm from 2482mm, you are either extremely unusual or insincere.
Nobody will ever convince anyone else that a centimeter is better or worse than an inch. Or a pound vs. a kilogram. It's a ridiculous discussion to have.
When the primary benefit of a choice is consistency, the outliers will always be able to argue that their system works for themselves. Which, unfortunately, misses the point.
Isn't that exactly the point. Why must people to adapt to the system, rather than have the system adapt to the people?
Metric system is a technocratic system. It has technocratic benefits. I value that a lot less than people, who, oh what a coincidence!, are already on the metric system.
I’m gonna make an educated guess that you grew up using imperial units. There’s nothing more “natural” to imperial units. An inch is as arbitrary as a centimeter and a foot as arbitrary as a meter. You can eyeball them all equally accurately, but the imperials are gonna kick your ass when you’re converting.
You have obviously never seriously used both systems. I use both everyday, and the Inch+ is still more familiar.
BUT metric is VASTLY superior and easier
Examples: Quickly subtract 5/8" of an inch from from 1' 5 25/32" or subtract 16mm from 452mm - which is easier?
Quickly add 3 tablespoons to 3/4 of a cup vs 44 ml added to 177 ml..
Hell, just measure something. That stock board is 8 feet 3/8 of an inch long and needs to be cut to 7'6" (or is it 78"). vs 2.448m cut to 1.98m, and even those would be more round numbers working with metric lumber & building.
Sorry, but the only reason you think it is awkward is that you don't use it regularly.
You can measure from 1nm to 1Em using a simple decimal scale, while with imperial you have to handle conversion from twip to inches to foot to yard to mile to league, all using different scales.
It's also not political insofar as whether we use metric or imperial de facto depends on the decisions of many thousands of manufacturers and suppliers, not the government. Are they going to outlaw all the imperial measuring tapes, or institute a buy back program?
In 1975, congress passed the Metric conversion act, and created the US Metric Board for planning, coordination, and public education.
This was disbanded under Reagan, particularly due to White House Advisor Lyn Nofziger's efforts [0]. The killing came from the conservative side, straight up.
And yes I was in HS then, and was very enthusiastic about the conversion, and the opposition was generally driven by conservative xenophobic sentiments (and frankly, laziness to learn a new system). I literally heard people say they "didn't want no damn foreign system here", nevermind their ignorance that "standard" wasn't invented in the US either.
The fact is that the same xenophobia, laziness, and willful ignorance is being exploited today to drive RW voting blocks. Metric is now so far off their anti-scale as to be invisible, but if another push comes, I can guarantee that the RW media will be all over the same anti-foreign-stuff on metric.
What's worse, I use both systems nearly every day in my work, and metric is WAAAY easier.
Example: Quickly subtract 5/8" of an inch from from 1' 5 25/32" or subtract 16mm from 452mm - which is easier? Or add 3 tablespoons to 3/4 of a cup vs 44 ml added to 177 ml.. Hell, just the notation in the "standard" system is insane, nevermind the origins (3 barleycorns to the inch or the length of the current king's foot...).
Yes, I get that doing conversions is a pain, but once you get used to the switch (maybe just spend a couple weeks in any other country) it is way easier. Opposition is really either political or an unwillingness to think about it.
[0] https://en.wikipedia.org/wiki/Metrication_in_the_United_Stat...
I've gotten into wood working the last few years and I've found that I'm significantly less likely to make a measurement mistake when I use metric. It seems like nearly all my measurement mistakes are when I did something in imperial.
So why don't I use metric all the time? Because materials are usually sold in imperial units.
Suppose you have a 30 cm piece and you need to evenly space 5 3.5 cm-wide wood planks on the 30cm piece. The decimal calculation will take you to a resolution you likely can't measure confidently (0.25 mm)
So US companies cannot export surplus and will need new tooling when they want to export. That makes it much more difficult to expand into international markets.
E.g. Japan use metric: https://www.kubota-chemix.co.jp/dcms_media/other/20161226_en...
Then... it just never completely took. Then those changes went away.
Part of it was political, surely (Carter spearheaded the metric change; Reagan coming in was super conservative), but I think you underestimate just how hard it is to get 50 halfway-independent states and millions of people to all agree on an entirely new system of measurement (not just of distance, but of volume, temperature etc.) when in millions of people's brains, the number 72 means "comfortable" (in Fahrenheit) and 100 means "hot!" (again, in Fahrenheit... you can't say "temps are in the triple digits!" in Celsius and have it mean anything other than that you're boiling), a tall man is "over 6 feet tall!", the average weight of an adult is 180 pounds, ovens get heated to 375 to bake something usually, shoe sizes (in inches), belt lengths (in inches), heck my baby's perfect bathwater temperature is exactly "100 degrees" (F, measured via infrared thermometer), going "100MPH" is VERY fast, 0 degrees F is VERY cold (-17C), etc. etc.
It's still used in some spaces like science, but in places like tooling it's both... I have 2 sets of EVERY TOOL (well, every tool with a fixed size at least, like sockets and allen-head wrenches), the metric version and the imperial version, it's maddening- basically the worst of all options is to get stuck in the middle, and that's precisely what happened with tooling.
Lastly, the digital tooling to automatically or easily convert is getting more common (a certain Reddit bot comes to mind which automatically converts any Imperial measurements cited in comments to metric), heck a browser plugin could probably do it for you
Why is this always seen as harder for US states than European contries? At least all the states speak the same language and federal laws whereas EU has to work with however many languages and a more complex system of laws.
And not every European country uses metric everywhere. Ask someone in the UK what their weight is, and if they don't tell you to buzz off they'll quite probably give you an answer in stone.
I don't think that's it - the Commonwealth countries only really started in the mid 20th century. Yes, the conversion isn't complete or stalled, but it has at least partially occurred.
Mostly non-European countries
> only really started in the mid 20th century. Yes, the conversion isn't complete or stalled
So once again, after the 1800s migrating to purely metric units everywhere became quite a challenge.
One could argue the switch to metric at least partially occurred in the US. My Nutrition Facts label here has grams and Calories. The medicine in my medicine cabinet is in grams and milliliters. My car has a 3L engine in it. I buy bottled beverages in 2L bottles. Over half the tools in my tool chest have measurements in millimeters, with most of the bolts and screws on my vehicles in millimeters. My backpack water bladder is 2L in size. My car's speedo does list the speed in km/h as well as mph. I use metric seconds, hertz, watts, amps, volts, etc.
https://en.wikipedia.org/wiki/Dagen_H
0F, it's cold and the wind chill makes it miserable. 0C? That's 32F, which is technically freezing but I can still work on my cars outside in that weather.
100F, sweaty, hot, chugging water if you're outside. 100C? GG, you're dead.
I don't care that 0°C is freezing for water, and 100°C is boiling for water. I am not water, I am a human. I would rather have a system that is human-centric, even if it is "arbitrary". 0°F is about as cold as you can go outside comfortably with a decent coat, and if it's 100°F, that's about the limit of what humans can tolerate too. If it's 100°C outside, you're dead, it's useless to daily experience, and to me, daily experience is far more important.
The best part is that isn't even true at different elevations. It makes no sense as a reference point for many people that live at higher elevations. What a weird thing to base a system of measurement on since it isn't constant.
Feels like something that's only going to go in one direction, even if not quickly in some cases.
Longing for the day you start using kilograms instead of points for weight in your movies and tv shows. I always have to pause and grab my phone to convert.
2.2 lbs per kg. Multiply by 2 and add 10%.
eg. 5 kg x 2 = 10 + 10% (1) = ~11 lbs.
0.45 kgs per lb. Divide by 2 and subtract 10%.
eg. 11 lbs / 2 = 5.5 - 10% (0.55) = ~5 kg.
It’s simply customs. And the system works. Why change?
It’s similar like asking why European football clubs wouldn’t want to change to the draft system of the US leagues.
European soccer is commercialized to a degree which is unthinkable for Americans, who are commonly regarded as the bigger capitalists…
I learned both metric and imperial measurements in elementary, middle, and high school. From what I understand they only use metric in science classes now.
It didn’t make sense to me at the time. But the. I saw what happened to Core Curriculum, CRT, and US history. And it all makes a lot more sense.
I agree that it's hard, but not the benefit is negligible. The cost of not switching is paid every time an american company needs to work with a company from elsewhere in the world.
https://m.media-amazon.com/images/I/51hAE7WuQZL._AC_SY1000_....
And for what? The imperial system is defined exactly in metric already as 254mm == 1 inch and has been de facto for 100 years.
Someone who's used to thinking in miles per hour suddenly seeing a sign in km/h will likely speed up to approximately 150% of the legal limit.
Occasionally hear grams for small amounts.
That's it.
It's a strange one though, isn't it? I was watching an exercise/nutrition video on YouTube earlier and the presenter was saying "to work out how much protein a day you need, multiple your bodyweight in lbs by X and that will give you the protein number in grams." It seemed so bizarre to combine the systems.
Edit: Just to add - in the UK we're taught entirely in metric in school, the bits mentioned above are just hangups / how it's done.
There is more than one way to lead your country back into the late neolithic, just go on.
In the 40+ years I've lived here I've only ever heard furlong used in the context of horse racing and the actor that played John Conner in Terminator 2...
Re the driving - about 35% of the world are on the left!
Source: https://en.wikipedia.org/wiki/Left-_and_right-hand_traffic
It does make things difficult for folks that slam their cars though when they don't want to rub, because there's less margin for error so they really need to measure the height of the tire.
Not too big a deal once you get a few basic conversions down.
6 feet and over is tall, 5 feet and under is short is such a handy rule of thumb, which I think is its longevity for height - although any official form will ask for metric (centimetres usually).
For everything else, what's the point in the government mandating it? There's no political desire for it because society in general doesn't care, and society doesn't care because the costs outweigh the benefits. There's no practical advantage to the average person to learn their height in meters instead of inches and feet, or to have to start shopping for hectograms of food when ounces work just fine.
Adams expected the report to catch fire and result in the adoption of the metric system. In actuality, it was a dud, and congress did nothing about it. His wife however noted in her diary “Thank God we hear no more of Weights and Measures.”
Society not caring about this issue is nearly as old as the country itself. But I can imagine John Quincy Adams, if alive today, would probably be just the type of person posting an “Ask HN” question on the US adoption of the metric system.
Combined with the concerns of another commenter who scratched his head about having to give his body length as 183cm, I come to the conclusion American brains overflow after 99.
Are you saying that you never used Fahrenheit for schoolwork? Or for anything?
We certainly never adjusted the thermostat in school, if that is what you are asking.
If someone asked me to read the thermostat at home for example, I just told them the numbers on it. It's not like "72 F" is radically different from "72 years old".
What I can believe, but would be nonetheless very surprised by, is that you have better intuition for 28 C, 25 C than you do for the equivalent Fahrenheit units if you were raised in the US.
I have no idea how to apply customary units for any real purpose other than "100 F is really hot". If you tell me you need to raise the temperature of a vessel that is 10 foot tall and 4 foot in diameter containing a solution of sodium hydroxide by 40 F I have no idea where to start. How many cubic feet are in a gallon? How many tonnes (of energy...) does it take to raise one gallon of water by 1 F?
But most of my usage of units is more of the form "Oh it's 60 degrees out today? Better put on a sweater!" than how "to raise the temperature of a vessel that is 10 foot tall and 4 foot in diameter containing a solution of sodium hydroxide by 40 F."
I, along with most replies, took you to be meaning that for the former usage you would use celsius, which surprised me. Nothing is surprising about the fact that for calculation of this sort you use metric.
This is not an argument against the metric system; I just cannot imagine foregoing imperial unit education and not having constant conversion pains in adulthood.
Anyone can use MPH on the road. If it's 60, you go 60. That is using the unit. It's not like the vehicles here sometimes display fathoms per fortnight. I still have no idea how much distance a mile is.
Anyone can go buy a gallon of milk. It's one gallon. There are no stores randomly offering to sell you a cubic yard of milk.
On the other hand, I know how many meters are in a kilometer, how many mm in a meter, etc. How to convert from cubic meters into liters, etc. That is a result of having learned the system.
By "know how much distance", you mean "able to decompose it into smaller subunit"? This is different from what I mean when I say knowing a distance.
You seriously were raised in the US and use celsius?
There was exactly one question I recall on a class exam about converting to Fahrenheit from Celsius. It's some formula with a constant & an offset to account for the differing scale and the freezing point. I've long since forgotten it.
My public school education prioritized metric and it’s trivial to choose units in maps, weather apps, etc.
I am having a hard time believing that a public school had this curriculum.
Since there is no practical benefit, most people don't care and aren't going to go to the effort. A vast amount of non-metric physical tooling already exists -- replacing it would be extremely expensive. For things like engineering, it doesn't matter because the units have to follow the values anyway; there are many common unit systems in engineering that are neither metric nor US imperial, and working across unit systems is something you always have to do anyway.
tl;dr: low ROI and high cost to switch
I was standing at one taking a look and an older couple came over and loudly exclaimed "It's a damn sacrilege to the memory of those young men who built the road they would go and change it like that."
They were adamant changing it to kilometers was unacceptable, because old reasons.
For example, I find that metric distance as commonly used doesn't have a good equivalent to feet for working with medium lengths. By "as commonly used" I mean that, while I could theoretically use decameters, in practice average people seem to only use millimeters, centimeters, meters, and kilometers. That makes it difficult for me to estimate medium lengths in metric. For example, it's awkward to describe someone as 1.83 meters or 183 centimeters tall. It is much easier to describe them as 6 feet 2 inches.
To a somewhat lesser degree, the same seems to be true for volume. In practice people only seem to use milliliters and liters. That leaves me with no good equivalent to cups or gallons.
Lol, funny how I'm the exact opposite. When someone says their height in meters I have a pretty good idea of their height, where as for feet, I always have to do maths in my head first. Same for volumes
I wonder if it's just a matter of better familiarity with one system over the other
That's purely subjective.
I'm from Europe and even though I'm a bit familiar with imperial units, I almost always need to use Google to convert feet and inches to metric.
And no one is going to convince me that fractional stuff like 3/16 inches is easier than 4.7mm.
In some of my Dutch cook book, there are mentions of cups. But mostly as a relative unit; add one cup of X, two cups of Y.
For absolute amounts, the metrics system just makes more sense, as it nearly combines the different quantities without weird conversion constants.
Note that in medical or scientific environments, centiliters are actually used.
But then again, we still use milimiter-mercury as a unit in medicine too ;) [0]
[0] https://en.m.wikipedia.org/wiki/Millimetre_of_mercury
For instance, the imperial gallon is about 4.5 liters, while the U.S. gallon is only about 3.78 liters.
The imperial system used to be much worse... there were separate gallons for wine, ale, grain, etc. About the only vestige of this is in barrels, where a barrel of beer is not the same size as a barrel of oil.
There's also an avoirdupois system, which is similar, but once again, not identical, with the imperial and U.S. systems, and the troy system used for precious metals and things of that nature.
Also, deciliter is used a lot for volume, especially for drinks. Everyone in Serbia knows that 0.5dl of rakija (brandy) is the way to go and when bar serves 0.3dl they don't respect traditional values :)
Also, 2dl is standard cup size and that's intuitive size when we have to estimate deciliter or two for cooking etc.
Also the meter, mm, and km are cool, but the cm is just the wrong size. Too small.
Everyone uses decimeters where I'm from, it isn't strange at all and everyone understands it. People use mm, cm, dm, m or km depending on what fits best, that gives you a much more fine grained set of lengths to talk about and it is trivial to convert between them so people don't have to think about it.
Maybe countries that doesn't use metric in everyday life just teaches you cm and m, but there is no reason to just stay with those. The confusion is maybe that we don't mix units, you don't say "1 meter 8 decimeters and 3 centimeters", you just use one, and in those since the accuracy is in centimetetrs you just use centimeters, or meters straight. But if you talk about a distance of around 30 centimeters people just say 3 decimeters, and since everyone has worked a lot with those before they take their mental decimeter times 3 and they know the length.
If you really want to complain about metric, complain that it is base 10 instead of base 12. Twelve is evenly divisible by 2, 3, 4 and 6 making dividing into fifths, quarters, thirds or halves easier, while decimal is only divisible by 2 and 5, which base twelve already does and more and more difficult to divide into quarters and thirds. This is why clocks have 12 hours per half day instead of 10.
In fact, I've seen the argument made that feet, inches, miles, cups, teaspoon, Fahrenheit, etc are superior to meters, centimeters, km, mL, Celsius, etc for everyday use. As I've seen it presented, this argument contends that centimeters are too small, while meters are too large for many common things you want to measure, such as the height of a person. Likewise cups and teaspoons are actual objects that you could visualize and get a general sense of the amount without even knowing the actual measurement. Same kind of thing for Celsius: the most common usage of temperature measurement for the average person is air temperature. For the set of air temperatures commonly experienced on Earth, Fahrenheit provides more precision.
Of course, there are clear examples when metric is both easy an intuitive. In everyday usage there are many cases where Imperial is beneficial (cooking -- metric is poor for individual servings, height and weight metric is inefficient as the modal height starts with the same digit, temperature requires more digits).
2L bottles of soda, 2.4L engines, 100m races, 5K runs, 2cc injections, 20 kilo drug busts, 11mm wrenches, M5 screws
https://www.youtube.com/watch?v=nRnuY1Vao0o
The timestamp where he's directly talking to what I mean:
https://youtu.be/nRnuY1Vao0o?t=1192
In it, he mentions the main reason why he doesn't use the metric system: he can't. Inches and feet and miles and ounces and pounds are so deeply ingrained in his mind. Even when he tries to relate to metric, its always in relation to imperial units, because to him its not about 30 centimeters its about a foot. Its not about a kilogram, its about two pounds. He can do the conversions in his head usually, but actually visualizing how far 5km is means converting it to miles which he can conceptualize.
Its like learning another language. Sometimes people are really great about just remapping their brain, but many people just end up internally translating things instead of actually deeply adopting the language. And if they're going to just be constantly translating it, it'll just be uncomfortable for them, and they won't want to do it. Because to a certain extent, what's the harm in my speedometer being primarily miles per hour? What's the harm in having a sign say "Rest Stop 5mi" instead of "Rest Stop 8km"?
I'm pretty similar to Johnny here. I can easily visualize ~300mi on a map. 300km? I know it is a good bit shorter than 300mi, but just at a quick off the top of my head I wouldn't quite know how far that really is. I'd be just doing the conversions in my head which takes me a second to think "ok, so divide by 1.6ish, so that's a little over 180 miles..." which I'd then use to conceptualize how far that is.
Changing to metric isn't just changing all the highway signs. Sure, that could be done in just a few years if we wanted to. Its changing how everyone actually thinks, how everyone is actually wired. That's what holds up the US from actually adopting metric.
But in the end, I still do use some metric. This drink I'm drinking has its nutrition label in grams/milligrams/Calories. My child got 1mL of iron supplements and vitamins this morning. It will be a long series of small steps before people get used to the change. Just swapping all the road signs overnight isn't going to lead to very happy people.
Back when most of Europe adopted metric, 40% of the population were illiterate. Tons of people didn't really deal with a lot of weights and measures in their daily lives. We live a very different world today than when metric was adopted in most of the world.