Metric versus Imperial Discussion

[drtimhill]

2, 4 and 5,280. The volume measurements aren’t hard to remember. And I already said length measures are better in metric. You didn’t address my points at all.

The point of the metric system, and specifically the SI system, is to provide a coherent system of units that spans both technical and scientific disciplines. A huge amount of effort went into SI units to eliminate almost all the arbitrary "magic constants" that were needed to translate and scale units, all of which were a source of errors and confusion. There is no point arguing "X is easy to remember" if X can be eliminated entirely as superfluous. Occam's razor.

Other examples of rather clever metric system advances: A4 paper vs letter, and pen width sizes. The "A" paper size is not arbitrary, the ratio of the width to length is 1 to square root of 2, which has the special property that when you fold (say) an A3 sheet in half your get an A4 sheet which has the SAME aspect ratio but is ½ the area. This means you can photocopy an A3 page onto an A4 copy without distortion or messed up borders (this is important any time technical diagrams or drawings are created). This is not true of imperial paper sizes.

 

[Cosmacelf]

The point of the metric system, and specifically the SI system, is to provide a coherent system of units that spans both technical and scientific disciplines. A huge amount of effort went into SI units to eliminate almost all the arbitrary "magic constants" that were needed to translate and scale units, all of which were a source of errors and confusion. There is no point arguing "X is easy to remember" if X can be eliminated entirely as superfluous. Occam's razor.

Yeah I know all this. It's pretty obvious that for scientific (especially) and engineering (less obvious, lots of legacy units still used because they are useful), SI is a better system. Most people aren't machines and they (usually) aren't scientists and thus for everyday usage where people don't need to convert units, having a measurement system that is simple (for them) is better. When do I need to convert temperatures, volume or weight in ordinary usage? I don't.

Each industry has their own legacy units. What kind of paper do you buy for your ink jet printer? Either 20, 22, or 24 pound paper, right? Do you know, or care that 24 pound paper is 90 g/m^2 to use the SI unit? How is saying, I need "90 grams per square meter paper" better than saying I need "24 pound paper"? Who cares, except that one is easier than the other.

Metrification doesn't come at zero cost either. For the world's largest economy, the costs to convert are huge and will carry its own share of problems. Various industries have converted even in the US and it wasn't cheap and without problems.

Anyways, while these debates are potentially interesting from a "learning how the other side thinks" point of view, at the end of the day, I don't see any movement in the US towards metrification. And I'm not sure anyone here is learning anything from what I'm saying either.

 

[scaesare]

... everyday usage where people don't need to convert units...

I think this is pretty common. "Everyday usage" is a bit of hyperbole typically representing "relatively common usage". even if if not every day.

Cooking or baking: oz, teaspoons, tablespoon, cups, etc...
Household/property length measurment: (fractional) inches, feet, yards
Cooking/shipping weight: (fractional) pounds to pounds

Thise are pretty darn common events. Heck just the cooking/baking alone could make unit conversion close to an everyday event for many households. And this ignores work scenarios....

 

[TunaBug]

Each industry has their own legacy units. What kind of paper do you buy for your ink jet printer? Either 20, 22, or 24 pound paper, right? Do you know, or care that 24 pound paper is 90 g/m^2 to use the SI unit? How is saying, I need "90 grams per square meter paper" better than saying I need "24 pound paper"? Who cares, except that one is easier than the other.

I wrote a paragraph on the stupid "basis weight" system which is more complicated than people realize. However, that doesn't change the fact that I agree with your overall point that the practical benefits of the two systems are moot if you only care about "I want heavier paper", where you can just get the next bigger size.

What a lot of people fail to remember is that the "legacy" systems evolved in a way that made sense for their situation at the time they evolved. You go to the town bazaar to buy cream. A bucket (or pail, actually) used to be called "gallon". But you don't want a bucket of cream so you tell the man "I just want half a bucket" or "...quarter of a bucket". The more common mini-buckets got their own names. It is no accident that the number of ounces in a gallon (U.S., not Imperial) is exactly a power of two. These systems made sense for the people that created them. At some point people standardized the sizes of their pails (gallons) so that people stopped getting ripped off by the farmer who sold cream in a slightly smaller pail.

Base 10 systems make a lot more sense once the masses can do arithmetic. And having units that combine easily is super convenient only after people have figured out that it is useful to combine them. If nobody has yet discovered "power = mass * distance / time" then is there any use in easily combining those numbers?

But it's 2022 AD, not 2022 BC. We know that it's useful to combine mass, distance, and time into "power", it's really nice to not have weird conversions, most of us have been educated in how to do arithmetic, and our calculators understand decimals.

 

[Cosmacelf]

But it's 2022 AD, not 2022 BC. We know that it's useful to combine mass, distance, and time into "power", it's really nice to not have weird conversions, most of us have been educated in how to do arithmetic, and our calculators understand decimals.

99% of the population have never calculated power = mass * distance / time after high school (if even then). Even very accomplished and intelligent people like filmmakers, writers, artists, actors, lawyers, politicians, sales people, business owners, etc. have never done that.

 

[Cosmacelf]

I think this is pretty common. "Everyday usage" is a bit of hyperbole typically representing "relatively common usage". even if if not every day.

Cooking or baking: oz, teaspoons, tablespoon, cups, etc...
Household/property length measurment: (fractional) inches, feet, yards
Cooking/shipping weight: (fractional) pounds to pounds

Thise are pretty darn common events. Heck just the cooking/baking alone could make unit conversion close to an everyday event for many households. And this ignores work scenarios....

Hallelujah! A post relevant to what I've been saying instead of ignoring what I've been saying and bringing up something else. Thank you @scaesare!

Yes, kitchen measurements are odder than most. However, not sure the metric equivalents are any better. These pictures are from Canada Amazon which sells stuff for a metric country. I'd say it is a wash, ease wise, but at least opinions can vary on this one.

Length measures, yeah metric is better, but only because we actually use centimeters. It is kinda annoying though, I must say, that when I look at, say actual width and lengths of a TV or most appliances, they are invariably quoted in mm. So I have to do a mental 1/10 adjustment right there (yeah I know, not hard, but decimal points do get slipped from time to time) to get to a unit that you can get a feel for. Quick, is 1829mm a tall fridge?

 

[Ben W]

Each industry has their own legacy units. What kind of paper do you buy for your ink jet printer? Either 20, 22, or 24 pound paper, right? Do you know, or care that 24 pound paper is 90 g/m^2 to use the SI unit? How is saying, I need "90 grams per square meter paper" better than saying I need "24 pound paper"? Who cares, except that one is easier than the other.

Agreed, legacy units are fine when you don't need to do computations with them. It's not like anyone needs to convert 24-pound paper to 384-ounce paper. If you're curious, the "pound" here refers to the literal weight of a 500-sheet ream of paper at 17" by 22" size. (Or equivalently, 2000 sheets at US letter size.)

By the same token, it would probably work just as well (for the consumer) to call the common paper weights "light", "medium", and "heavy", similar to how eggs are sold as "Medium", "Large", or "X-Large". Heck, even rockets are sometimes just called "Heavy" and "Super Heavy"! And I'm off to Costco to buy a Big Falcon Ream of paper.

 

[STS-134]

Hallelujah! A post relevant to what I've been saying instead of ignoring what I've been saying and bringing up something else. Thank you @scaesare!

Yes, kitchen measurements are odder than most. However, not sure the metric equivalents are any better. These pictures are from Canada Amazon which sells stuff for a metric country. I'd say it is a wash, ease wise, but at least opinions can vary on this one.

Try tripling or quadrupling a recipe in imperial units. It's a pain in the ass. What about scaling the recipe up by 50x? How much is 50 tablespoons again? Easier to just use mL.

 

[TunaBug]

Agreed, legacy units are fine when you don't need to do computations with them. It's not like anyone needs to convert 24-pound paper to 384-ounce paper. If you're curious, the "pound" here refers to the literal weight of a 500-sheet ream of paper at 17" by 22" size. (Or equivalently, 2000 sheets at US letter size.)

What you said is for office paper that you print or write on. It's a ream of paper at the basis size for the paper, where basis size traditionally was whatever your mill started with before trimming down. For example, if you hand produce small sheets of 9x12 with rough edges, intended to trim them to a perfect 8.5x11, then the 9x12 would be your basis size.

Since then industry segments have agreed on basis sizes, but segments use different sizes. Office paper is 17x22 as you say. But cardstock at 8.5x11 uses a larger basis size, and large paper for magazines is another size, and the stuff for high speed presses for newspapers is another. So it's better to not fall into the habit of "Or equivalently, 2000 sheets...". But this is all localized knowledge in your industry: if the number is important then you either know it or you're new and your coworker will tell you.

 

[ICUDoc]

An interesting side note is that the unit of fuel consumption is technically area: volume (of fuel) divided by distance (traveled).

Ha! I'd never thought of it this way- that's cute.
But maybe one should say "has the same dimensions as area"??

 

[scaesare]

Hallelujah! A post relevant to what I've been saying instead of ignoring what I've been saying and bringing up something else. Thank you @scaesare!

Yes, kitchen measurements are odder than most. However, not sure the metric equivalents are any better. These pictures are from Canada Amazon which sells stuff for a metric country. I'd say it is a wash, ease wise, but at least opinions can vary on this one.

View attachment 887602

View attachment 887601

Length measures, yeah metric is better, but only because we actually use centimeters. It is kinda annoying though, I must say, that when I look at, say actual width and lengths of a TV or most appliances, they are invariably quoted in mm. So I have to do a mental 1/10 adjustment right there (yeah I know, not hard, but decimal points do get slipped from time to time) to get to a unit that you can get a feel for. Quick, is 1829mm a tall fridge?

(Note: Given this is a dedicated "off topic" I'll play along... appreciate that it's been a courteous discussion thus far)

I think the issue with this would be that the volumes being depicted are the equivalents for imperial "defaults".

My guess is that if metric were the standard, then the default measure would be 250ml, not "1 cup". Recipes would be scaled to use a default (fractional) measurements that fit nicely: 1/2 kilogram instead of pound, 250ml instead of cup, increments of 1/5/10 ml for "the spoons", etc...

So rather than convert to an awkward metric equivalent, scale your recipes to fist the reasonable metric default

In much the same way that we gradually got used to liters for soda and engines (and wine/booze), they are the default volumes expected now.

Quick, is 1829mm a tall fridge?

I admit, I also mentally did a mm-to-meter conversion, and seems about average to me. I agree that it seems weird to use mm in this case. Actually in my first reply I mentioned that units that allow you to use 2-3 digits for common usage seem to be comfortable... I woulda preferred "1.83m"

But again, frame of reference probably matters more... if you are used to major appliances in mm, you can mentally grasp the approximate scale.

Interesting example, I grew up when engine sizers were cubic inches. They started being spec'ed in liters when I was a teen. I always had to convert to CI ( CI=L * 61) in my head to get a grasp of the relative displacement. Now that it's been commonplace for years, I no longer have to, and it's actually much easier mentally.

 

[scaesare]

Other examples of rather clever metric system advances: A4 paper vs letter, and pen width sizes. The "A" paper size is not arbitrary, the ratio of the width to length is 1 to square root of 2, which has the special property that when you fold (say) an A3 sheet in half your get an A4 sheet which has the SAME aspect ratio but is ½ the area. This means you can photocopy an A3 page onto an A4 copy without distortion or messed up borders (this is important any time technical diagrams or drawings are created). This is not true of imperial paper sizes.

This is very clever... did not realize this. Thanks for that.

 

[Cosmacelf]

(Note: Given this is a dedicated "off topic" I'll play along... appreciate that it's been a courteous discussion thus far)

I think the issue with this would be that the volumes being depicted are the equivalents for imperial "defaults".

My guess is that if metric were the standard, then the default measure would be 250ml, not "1 cup". Recipes would be scaled to use a default (fractional) measurements that fit nicely: 1/2 kilogram instead of pound, 250ml instead of cup, increments of 1/5/10 ml for "the spoons", etc...

But metric IS the standard in Canada and much of the world, yet the volume measures that you can buy still hew to the old measurements. I just checked the Amazon website in France. Same thing. Cooking measures are all based on imperial volumes and simply converted over one to one, along with a nice conversion chart from imperial to metric. And France is the birthplace of SI units!

My point here is that converting units isn't as simple as it would appear...

 

[drtimhill]

This is very clever... did not realize this. Thanks for that.

It's actually even more clever, as the drawing pen ink widths are also in the same ratios, so if you want to correct a line on a drawing that was reduced from A3 to A4, you just choose one pen width down and the corrections will have a matching stroke width. (This was all of course when diagrams and tech drawings were done by hand.)

Incidentally, the A0 (biggest size) paper was chosen so it has exactly 1 square meter of area (with the 1: root 2 aspect ratio). There is also a (less used) "B" series, which start with B0 having a short side of 1m (and a long side of root 2 meters).

 

[ecarfan]

Yes, kitchen measurements are odder than most. However, not sure the metric equivalents are any better. These pictures are from Canada Amazon which sells stuff for a metric country. I'd say it is a wash, ease wise, but at least opinions can vary on this one.

That Amazon graphic is not accurate, it is rounding the ml values to make it look like imperial volume measurements for fractions of a cup are easy to remember numbers. They are not. For example, 1 cup is actually about 237ml, not 240m.

Of course in cooking 3ml either way makes no difference. But as others have noted, the point remains that if one wants to halve or double a recipe that is in imperial units it can be a real headache to figure out.

 

[drtimhill]

Yeah I know all this. It's pretty obvious that for scientific (especially) and engineering (less obvious, lots of legacy units still used because they are useful), SI is a better system. Most people aren't machines and they (usually) aren't scientists and thus for everyday usage where people don't need to convert units, having a measurement system that is simple (for them) is better. When do I need to convert temperatures, volume or weight in ordinary usage? I don't.

(Dating myself here). When I was growing up in the UK, the monetary system was based on "pounds, shillings and pence" (amusingly abbreviated to LSD since "L" is the symbol for a pound and "d" for one penny, from the Latin), where one pound sterling equalled 20 shillings, each of which was worth 12 pence (for 240 pennies per pound). In the early 1970's the government "decimalized" the currency, replacing shillings and pence with a "new penny" with 100 pence to the pound (thus making 5 new pennies equal to one old shilling). Everyone screamed and hollered that the world was going to end. It didn't, and today anyone under (say) 50 looks at you like you are crazy when you explain the old system (as they should).

The imperial system is actually massively expensive to maintain, as any international trade is in metric, and converting back and forth is a mess and error prone, even with computers in the middle. It impacts in the medical, aerospace, and any industry that reaches outside the US borders (which is most, these days).

 

[jabloomf1230]

(Dating myself here). When I was growing up in the UK, the monetary system was based on "pounds, shillings and pence" (amusingly abbreviated to LSD since "L" is the symbol for a pound and "d" for one penny, from the Latin), where one pound sterling equalled 20 shillings, each of which was worth 12 pence (for 240 pennies per pound). In the early 1970's the government "decimalized" the currency, replacing shillings and pence with a "new penny" with 100 pence to the pound (thus making 5 new pennies equal to one old shilling). Everyone screamed and hollered that the world was going to end. It didn't, and today anyone under (say) 50 looks at you like you are crazy when you explain the old system (as they should).

The imperial system is actually massively expensive to maintain, as any international trade is in metric, and converting back and forth is a mess and error prone, even with computers in the middle. It impacts in the medical, aerospace, and any industry that reaches outside the US borders (which is most, these days).

As was mentioned before, academia is 100% metric No US corporate entity that sells goods, solely uses the Imperial system. Metric is used and if not, metric equivalents are used in addition to Imperial.The Imperial system is a private citizen artifact, because US politicians are afraid that a political backlash would occur if road signs and weather reports all of a sudden became metric. Honestly, I don't think that anyone in the US really cares about switching systems.

 

[Ben W]

What about scaling the recipe up by 50x?

As one does. You should see the size of my cookie sheets.

 

[Ben W]

But maybe one should say "has the same dimensions as area"??

You can think about it like this: a vehicle could keep traveling indefinitely if it could ingest a thin stream of fuel along its path. The cross-sectional area of that stream is the "area" of its fuel consumption rate.

And btw, I had my math wrong for Starship. 1200 metric tons of fuel (about 1200 cubic meters) over 10,000km is equivalent to 1200 liters per 10km, or 120 liters per km, or about 0.02mpg, or (area-wise) about 1.2 square centimeters. That's pretty gas-guzzling, but still about twice as efficient as (say) the QE2 ocean liner. Of course, the QE2 could carry 1900 passengers; Starship would have to cram in about 1000 passengers per trip to make the per-passenger-mile efficiency work out the same as QE2. But then, methalox has quite different production and emission characteristics from cruise ship fuel. So the environmental friendliness may ultimately turn out to favor Starship, even with only (say) 200 passengers per trip.

 

[scaesare]

But metric IS the standard in Canada and much of the world, yet the volume measures that you can buy still hew to the old measurements. I just checked the Amazon website in France. Same thing. Cooking measures are all based on imperial volumes and simply converted over one to one, along with a nice conversion chart from imperial to metric. And France is the birthplace of SI units!

My point here is that converting units isn't as simple as it would appear...

Well, I'm not arguing that conversion between systems is any better/easier. I'm addressing your premise that the imperial system is inherently better for "everyday" things, You said:

For everyday usage (non scientific, non engineering), imperial is a better system.

Have you ever used a Celsius thermostat? You set the temperature using 0.5 degree increments. How is that better?

How about buying meats? A pound of ground beef is a useful standard measure for cooks. A kilogram is too big a unit for most things. Likewise for weighing yourself. For pounds, decimals really aren’t needed, kilos, they are. And ounces are again a useful measure, grams are way too small.

So your premise is that, because the units "match" commonly occurring scenarios, Imperial is "better". As has been pointed out, there are also lots of places where Imperial doesn't conveniently provide non-fractional units of a reasonable number of digits. In addition, there are a number of other places where it's awkward, and conversion is one of them.

What I think was meant by that (or at least what I meant) was conversion between units within the same system. And given that Imperial is "random base", as opposed to metric's all-base-10, I don't think there's really any question metric wins that one. My "recipe" example was to point out that conversion (within a system) is a common scenario, and Imperial's awkwardness there is a factor in your "everyday usage" category.

Now... the converting between system you bring up, I suspect is not quite as every-day of an occurrence, but pretty common nonetheless. I think your example of the situation in Canada and France[1] is simply an argument for the need to settle on a single system, and scale "default" amounts to the right unit. Once everybody uses recipes (or whatever) that default to kilograms and milliliteters (instead of pounds and tablespoons)... that problem goes away.

Neither imperial nor metric is superior in eliminating the pain between converting between the two. But That's not evidence that "for everyday usage (non scientific, non engineering), imperial is a better system."


[1] Incidentally I suspect that the reason Canada does this is because of France's presence there... they are rather insistent on "their way".