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Comment by andreygrehov | Hacker News Reader

rant: I live in the US for more than 10 years and I still can't get used to the imperial system. I never will. It just doesn't make any sense to me. The metric system is pure gold:

  1cm = 10mm
  1m = 100cm
  1km = 1000m
  1kg = 1000g
  1ton = 1000kg

The imperial system is like, hold my beer:

  1in = ???
  1ft = 12in
  1yd = 3ft
  1mile = 5280ft
  1lb = 16oz

Jesus Christ, who the hell came up with this madness?

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What I've come to realize, also from living in the US, is that most Americans just don't convert between units. Unless they really have to. That way the issue does't really come up much.

I notice it most when things here by chance are done in metric, but the units still aren't converted. E.g. I might see something listed at 1000mL, instead of just writing 1L. Or 3500g instead of 3.5kg.

Sometimes a European might say "This way is 600m, but that way is 1.2km", an American would never say "This way is 800 yards, but that way is a mile". A European might say "I had to carry 4L of water, so my bag got 4kg heavier". An American might say "My bottle is 24 (fluid) oz, so it's about 24 (weight) oz", but if it's a gallon, they probably just say it weights around a gallon.

All I'm saying is that the conversion problem has turned out to be less of an issue than I imagined. Simple because Americans don't run around converting their units every sentence.

It seems like many Americans are really confused about weights and volumes, because of this unit system.

Like if you say to use 300g of flour, the response will automatically be « How many cups is that ? ». And the answer is that you can’t measure flour correctly by volume.

Measuring dry ingredients by volume is like a recipe brown M&M, at that point you know the recipe is bad and you should look for another one.

... which is a natural result of such an obscure system that is needlessly complex for everybody involved. If you can't do conversions on spot as a population, you simply over time don't do it and this state becomes natural. Just like for us literally everywhere else in the world we convert and literally everybody with even very subpar intelligence can be discussed with in such units.

Suffice to say, we had tons if very similar obscure systems in medieval Europe, even my tiny eastern country had at least 6 with various absurd conversion schemes for lengths, volumes and weights. These days we go to museums or medieval wiki pages if we want to see that. The thing is, we moved to modern era and absolutely nobody looks back.

I suspect with US its more an ego thing and swallowing pride that somebody else can he it simply better, rather than anything else. I mean whenever US actually needs to do some proper science and achieve great stuff, it turns quietly to metric/liters/kilograms. We have 10 fingers 100% of the time right in front of our face and everybody learns to count on them first, there is really nothing more natural.

> I notice it most when things here by chance are done in metric, but the units still aren't converted. E.g. I might see something listed at 1000mL, instead of just writing 1L. Or 3500g instead of 3.5kg.

I see things like this constantly in shops in Europe. I think it is part of a dark pattern to make price comparisons less intuitive and even misleading if you just skip over the prices trying to find the cheapest. What is cheaper, the product advertised as $X per liter or the one priced $Y per 100ml? There usually isn't a significant difference in packaging volume or usage that would otherwise explain why anyone would use different units for each.

> I see things like this constantly in shops in Europe. I think it is part of a dark pattern to make price comparisons less intuitive

In Germany they put the price of a unit on the price tag. So that you can clearly see that 0.33 bottle of Coke is more expensive (per liter) than the 1l.

Germany is a big user of the trick "lemme change the unit from €/kg to €/100g in this part of the shop", for example at the cheese counter, which is what the parent is saying. It was the same trick used in the UK. I believe it comes from a european rules which allows such labeling if the packaging is small.

In France it is always labelled in €/kg or €/L consistently through the shop.

>€/kg to €/100g

Knowing the price of saffron for 1kg would be a really impractical information

In almost every European country, stores must show the price per liter or kg.

At least in Germany shops play rather loosely with the units. Yes, you have €/kg but you also have €/100g, €/g, ... and they will switch between them even for near identical products. Can't cheat buyers out of money by selling them a 30% larger bottle if you make it too obvious that they are paying 40% more for it.

I’m puzzled by this. How hard is it to convert prices by powers of 10? Do the same thing with $/lb and $/oz, and I’d be lost.

Edit: Oh wait, I get it. It’s just that a price per 100 g is an order if magnitude less than per kg, so psychology kicks in and makes it look cheaper, even though the conversion is trivial. A bit like the 9.99 effect.

But this could just be part of the pattern of Europeans being more lose with unit changing, because it's so easy to do anyway. People just tend to use the units that keep the values in a reasonable range of 1-10.

> > I notice it most when things here by chance are done in metric, but the units still aren't converted. E.g. I might see something listed at 1000mL, instead of just writing 1L. Or 3500g instead of 3.5kg.

> I see things like this constantly in shops in Europe. I think it is part of a dark pattern to make price comparisons less intuitive and even misleading if you just skip over the prices trying to find the cheapest.

It doesn't really matter though, as conversion is so easy and automatic.

Meanwhile in the US, if I want to determine which product has more fat, my butter lists nutrition per tea spoon, my milk by the cup, my yogurt by 3/4 of a cup, another butter per 100g, yet other products per 24 ounces.

Honestly I don't know if anybody is able to extract useful information from those comparisons, without pulling out a calculator in the super market.

I think there’s even a lot of people who grew up in America that don’t fully get our system.

I would be surprised if more than 50% of the population knows how many ounces are in a cup of water. Same for feet per mile, etc.

Thank goodness even in the US the metric system is used as standard within the science community.

In US customary units, a fluid ounce of water does not weigh an ounce avoirdupois, because US volume measures are not Imperial units: they are based on the pre-Imperial Queen Anne wine gallon.

The British fluid ounce was defined to be the volume of an ounce of water, and the Imperial gallon was defined to be the volume of 10lb of water. This vague nod towards decimalization happened to match the pre-Imperial beer gallon fairly well, and it’s also why the Imperial pint has 20 fl oz instead of 16.

You missed a few intermediate units, which might help somewhat to explain it:

Derived from surveyors’ tools, a chain is 22 yards. (It is also 4 rods, making a rod equal to 5½ yards; go figure.) Ten chains make a furlong, and there are 8 furlongs to a mile. So there you are. Incidentally, an acre is 1 furlong × 1 chain. It may be madness, yet there’s system in ‘t.

This is one of those cases where I can’t tell if a comment is sarcastic or not.

Those cases are the best, are they not? But yeah, a large dose of sarcasm was intended. And a little bit of seriousness.

> 1in = ???

What do you need to convert those inches into? Why would you ever need to convert those inches into miles? Nothing you will ever do in life requires you to convert between inches (or feet and inches) and miles.

Do you mean because people just use metric in those contexts, or that everyone avoids math?

I assure you people regularly figure out how many small things fit in a large thing. I places where those things are measured in feet and miles, that's what they'd use.

I mean that in every context where a person would ever have to convert units or do long division, we invent a new set of units instead.

Others have given other examples, such as printers who divide the inch into points and picas. They do this because it makes figuring out how many characters fit in a line of type easier than if they measured the type in fractions of an inch. It lets them work with integers instead of fractions all day. Of course these days it’s all computer–driven and it hardly matters what units printers use; the computer does the counting and could just as easily do it in fractions of an inch.

Do you buy gravel by the cubic mile then?

Weird real-life unit conversions come up all the time, often when you need to calculate a net weight or price, and you have some big surface area (eg. a road, with width in yards + feet, thickness in inches, and length in miles), and your gravel supplier prices by ton, and you look up the density in a conversion table and see something like lbs/ft^3, and now you have a whole bunch of opportunities to make a mistake.

Gravel is purchased by the yard, not by the cubic inch or mile.

I'm certain it's by weight, but either way, I don't see that helping much.

Sellers price it by the weight, purchasers buy it by volume.

A reservoir is 3 sq miles, the level rises by 7 inches. How many acre-feet of water have been added :)

Bonus point: how many cubic yards of water added?

The owner of the reservoir doesn’t bother to measure it in square miles, he measures the acreage. Then the acre–feet becomes a trivial computation. Yes, if pressed he might dredge up the obscure fact that a square mile is 640 acres, but then he would have to do long division to convert it, and the whole point is to avoid that kind of complexity.

You have to lay 3miles of pavement, 5 feet wide, bricks are 5x10 inches. How many bricks to buy?

You have 4 square mile of land with dense forest. Trees grow 5 feet apart and are 10 inches thick on average. How many trees are there? How much wood can you expect?

There's 5 inches of snow on your 5000 square feet roof. How much does it weight? Can it break the roof? Should you clean it up or can it stay?

These things are mental-math in metric and notebook-math in imperial, and that sucks.

Of course you can work around that. People always avoid the bad parts of the tools they use and find workarounds. Like not using exceptions in C++ or comparisons in javascript. If it's a widely used tool you know it has to work somehow.

Thus Americans never convert between units unless absolutely necessary and write press articles like "Asteroid the size of 3 elephants missed Earth by 1000 football stadiums" :)

But let's not pretend it's not a problem.

You kind of mess it up from the beginning by assuming everything is based of 5 or 10 unit fractions for the math. Do it with 2,3,4,6,8 inch standards and metric becomes notebook and imperial becomes mental.

Printing measures go smaller than an inch. The width of printed columns is measured in “picas.” 12 “points” equal one “pica”; 6 picas equal 1 inch. We still use those in image resolution measurements.

Yes, this is a great example of what I mean by everything having their own set of units!

Unit conversions are inconvenient for sure, but I think the worst part is actually fractional length measurements. It may make sense for woodworking and handicraft, which I assume is the origin, but for any other use? Try reading 2 3/16" on an imperial ruler as quickly as 5.6cm. Screw sizes also get affected by this.

As someone who uses imperial measures, it is incredibly fast and easy to read fractional inch measures on a measuring tape or ruler because each fractional unit is half of the previous unit size, and they are marked to differentiate each half size measure from the previous for quick reading. To speed things up I wouldn't count three ticks, I would use a 1/8th tick mark count up one more 1/16th tick.

If you find it difficult, it is merely due to lack of experience in using fractional measures.

As a European having watched many house framer videos on Youtube, the imperial system of in/ft actually somehow makes sense there. As far math, it's pretty annoying, but as far as communicating ratios or dividing distances into halves or fourths, it seems like a better fit to the human brain.

Yeah, a lot of people really don't get how useful fractional measures can be for building and construction, or other tasks. You can do like 99% of the math required to build a residential home completely in your head, even if you aren't great at math to start with. You could even forgo a tape measure completely and build the house using a piece of wood with a mark to give a standard length and then doing all the rest with a piece of string you fold over for ratios of that length.

It even was really useful when I was making patterns and molds for industrial ceramics. Half the orders would be in metric, half would be in imperial, but was 90% of the time converted to imperial by everybody whenever possible despite knowing both systems because it was much faster to get work done using ratios of standard fractional sizes. Need more precision? Divide your unit in half how many times you needed.

> Jesus Christ, who the hell came up with this madness?

They made historical sense.

A foot is the distance in one step (ie, a foot placed after the other). A mile was the distance a person could walk in an hour. A pound was roughly a fist worth's of meat-- so if a piece of meat was fist sized it was roughly a pound in weight.

These were intuitive units that made sense when they were invented. It was only later on when we needed more accuracy that the metric system was invented

A mile an hour sounds rather like a leisurely stroll to me.

A mile was originally (in Roman times) 1000 paces, counting left-right as one pace. Normal walking speed is 3mph ish.

> 1in = ???

25.4 mm, ever since 1959 when we redefined it.

I believe an opportunity was missed some time ago in the past to define one inch to 25.6mm, which would make for much nicer conversions IMO, especially with the convention to use fractions of powers of two in the inch world (e.g. 15/16" would be 24mm exactly vs. 23.8125mm).

Usually the absolute value of units is preserved as much as possible when a unit is redefined.

In the 1800s when Britain and the USA stopped keeping their units in alignment, they both defined conversion factors in terms of inches per metre (the inverse of the modern definition). However the conversion factors were slightly different. In the 1920s and 1930s, Carl Edvard Johansson used 25.4mm as a compromise between the two definitions when making his guage blocks, and this became a de facto standard that was later blessed as the international standard inch.

https://en.wikipedia.org/wiki/Carl_Edvard_Johansson#Johansso...

Is it really novel to you that a more modern system is based on powers of 10 for ease of use? Were you just as mad when you discovered Egyptians used hieroglyphics as their method of writing?

I don't understand this feigned "outrage".

And even the beer you are passing is a 16oz pint, not a 20oz pint, as in the UK.

A 'pint' in the UK is 568ml, still I think. Maybe REUL will undo that. Some places you get half-litres.

An inch is an inch.

Not so quick: One inch may be 1/12 of a foot, but a foot is not necessarily a foot. The international foot is 12×2.54 mm, but a US survey foot is 1200/3937 m. The ratio of the definitions is 500000/499999.

But nobody would ever use a survey foot outside of surveying, and if you are using survey foot outside of talking to other surveyors you would call it a survey foot, or be using it in a context where that tiny inconsistency doesn't matter. Something being 5 feet away in feet is still for all practical purposes 5 survey feet away, nobody is going to pull out a 5 foot set of calipers to measure that 1/100,000th of a foot difference. And nobody would use survey feet for anything that requires that sort of precision.

You might as well complain about meter measurements from 100 years ago not being exactly the same as a modern meter.

Not complaining really. I mentioned this mostly for entertainment value, besides pointing out that things are not always as straightforward as it might seem. (Also triggered by the absurd precision of the number in the title.)

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