# Why doesn't the US use the metric system?

#### garthpool

The book "Measure of All Things" is a great read, well-written and extremely interesting. One of its most valuable revelations is that, despite the general belief, the metric system is not based on a natural and eternal truth.

During the measurements to establish the system, the investigators discovered that the Earth is not a perfect sphere. The length of a fraction of one meridian is different from the length of the same fraction of another. The length of a meter therefore depends on which meridian serves as the basis.

The French realized this toward the end of the project. They were too far into it to make any corrections, if that had even been possible. So they fudged things to establish what we now call the meter.

The metric system is no more rational than any other system. A useful system requires only agreement on which standard to use. The French chose the one they liked, and as the book explains, were able after a good many years to persuade many other nations to use it.

The use of the decimal for the system is vastly overrated. It makes sense for money, but in a physical measurement it is much easier and far more accurate to divide by two by the eye, as the US Customary System allows, than it is by ten. This matters in almost every measurement most of us make. Let the scientists keep their decimals. The carpenter and the cook have a better system.

Granted, it is inconvenient to have two measurement systems in the world, sometimes even deadly. A plane crashed because of it, costing lives. The Mars Orbiter was lost because of it, costing hundreds of millions of dollars and the loss of important opportunities in science.

But it would be extremely difficult for the US to change to the metric system. It would cost an enormous amount of money and aggravation, and it is not necessary. The one we are using is superior in many ways.

Sorry, nerds. You might think you sound superior by using kilometers instead of miles, but you are just following the mindless herd. We should not start calling the inch worm the centimeter worm.

nikkitickie

#### Hildy

Identity, politics and good, old fashioned resistance to change.

Why doesn't the US use the metric system? : Read more
One thing Garthpool and the article alluded to should be emphasized. Much of the Imperial System and none of the Metric System is human centric.

A mile is about a thousand paces (a pace is two steps) and dates to Roman times to measure an army's march and put mile markers on roads.

A yard is about the distance between your nose and your outstretched hand (and I can remember my mother buying fabric measured this way by a fabric shop).

A foot is about a foot (with or without a shoe, depending on your foot size if you want to be more accurate).

An inch was the width of an adult thumb (and children can use an appropriate finger joint).

As far as temperature Daniel Fahrenheit defined zero degrees as the freezing temperature of a brine solution which gave 32 degrees as the freezing point of pure water and 212 degrees as the boiling point. He divided the difference by 180 instead of 100 but it was as scientifically based as Celsius. The benefit that the human body recognizes variations in 1 degree Fahrenheit when setting, say, your heating (just ask my wife) while Celsius requires fractions to get to that point.

I will also point out that the French also created a calendar with a day divided into 10 decimal hours, an hour into 100 decimal minutes, and a minute into 100 decimal seconds. From the metric point of view, this makes far more sense than the current arrangement but it was laughed out of existence after the French Revolution and nobody mentions it anymore.

nikkitickie

#### Ts60423

This article implies we are not metric. We are. We use both.

The question for decades isn't "why aren't we metric," but instead "why do we use both?"

One could even argue that unless you measure heat in kelvins, you are not metric (Celsius is not metric.)

I have a 100 year old house. It isn't metric. We didn't have to build infrastructure from scratch after WWII, so we have countless legacy systems in place. Interestingly, the US military is 100% metric and has been since at least the 80's. All cars have been metric for decades. I teach both to my students in elementary school. Engineers use metric for design, then convert to imperial units afterwards, if at all. There is no 'going metric' because we did, but our homes (plumbing, lumber, etc.) are not convertible. I really don't notice, though I like my newer tape measures with both units, just to mess with the hardware store or my dad.

The question for decades isn't "why aren't we metric," but instead "why do we use both?" It is a history lesson and a marketing lesson, not a political one.

#### mulp

The US is metric. An inch is defined as 2.54cm exactly. The mass unit pound is legally defined as exactly 0.45359237 kilograms.

But then, for some units like pound-force, you must use the definition of slug, which is defined as the mass that is accelerated by 1 ft/s2 when a force of one pound (lbf) is exerted on it. But the slug is defined as 14.59390 kg. Thus pound force is indirectly defined as 143N/14.59390kg, or inexactly as 4.448222 N.

And so on.

SI is the product of physics and it has been modified as needed to conform to what physicists define as "nature".

The customarily used measures in the US are based on how most people think is the way the world works, ie, implicitly a pound is the force you put in a scale, not a mass, with gravity constant and fixed. Thus most measures are flexible, and imprecise. And thus can be given as absolutes. You can say something is a pound while I disagree with both being correct because pound is ambiguous with multiple definitions in customary use. Like Trump.

nikkitickie

#### twk

The others beat me to it and stole most of my thunder - (also I couldn't get the thumbs up button to work - Sorry garthpool, Hildy, TS60423 and, Mulp).

I've been saying for years that the Imperial System, for everyday use by people, is a Better System than the Metric.
As was stated before, degrees Fahrenheit are more accurate than degrees Celsius. The decade scale use for Metric units is too large a jump for most human, real-world applications. "Give me 0.5 liters of beer" just doesn't have the same ring to it as "Give me a pint!"Centimeters are too small and Decimeters are too big for a lot of human-scale things without a measuring device. "How big was the spider?" - America - "About an inch across" Some metric using country - "About 2.54 cm" ... Really? "How long is it from your elbow to your wrist?" "About a foot" or "About 30 cm, 3 dm, 0.3 meters" the scale jumps too far. I have some friends who visit the USA from France, even when I told him the measurements in Centimeters (doing some carpentry), he had to get out his metric tape measure and measure the distance because it was too hard to envision the distance without a measuring device. I've worked in the electronics field for a good number of years and know the SI units better than the average bear, but other than when talking about very large or very small things Nanometers, pico Farads, etc. Imperial units work much better for me, as do fractions a lot of the time. A pizza might be cut in half then quartered, then eights, with four swipes from the cutter. Next time you get a pizza, try and make a slice 0.125. When I was in school in the 60's and early 70's We learned the metric system - "The wave of the future" that was to make math easier, but it really didn't, I'd rather be 6 foot tall than 182.88 cm.

nikkitickie

#### Valentine Michael Smith

A convention has utility proportional to the person's mind using it. Like a verbal language, I speak old and new.

@garthpool : I told you money es on da way auht. And so will many tawdry 'hobbies' people have, like building stuff from scratch out of wood. And so on.....

#### KMacK

Because a lot of the "Never Metric" types run into trouble when they go past the number three. We ARE a metric nation, and slowly but surely a sensible system of measurement is taking over.
Honestly, a Foot is the length of thirty-six barleycorns laid end to end? A mile is one thousand steps (Maybe if you're a Roman - and the Roman Mile is shorter than the Statute mile). And converting Acres into Square miles and then into Rods...? Make mine METRIC.

#### Jim_WY

This article implies we are not metric. We are. We use both.

The question for decades isn't "why aren't we metric," but instead "why do we use both?"

One could even argue that unless you measure heat in kelvins, you are not metric (Celsius is not metric.)

I have a 100 year old house. It isn't metric. We didn't have to build infrastructure from scratch after WWII, so we have countless legacy systems in place. Interestingly, the US military is 100% metric and has been since at least the 80's. All cars have been metric for decades. I teach both to my students in elementary school. Engineers use metric for design, then convert to imperial units afterwards, if at all. There is no 'going metric' because we did, but our homes (plumbing, lumber, etc.) are not convertible. I really don't notice, though I like my newer tape measures with both units, just to mess with the hardware store or my dad.

The question for decades isn't "why aren't we metric," but instead "why do we use both?" It is a history lesson and a marketing lesson, not a political one.

I am an engineer (and millennial) and in the civil/structural world I would say the opposite. The vast majority of my designs and calculations are in U.S. Customary and I hardly, if ever, touch SI metric. twk is on the money. For many things the way the U.S. Customary system is set is better intuitively. I grew up being taught metric mostly in school with some U.S. Customary. Engineering school was funny because the first two years they pushed SI metric, SI metric, SI metric, well then we get into the final two years and grad school and you start seeing more U.S. Customary and then in the actual civil engineering field in the U.S. which is very heavy U.S. Customary. For machining parts and other things yeah SI metric works fine, and in some fields is the more advantaged system. When laying down roads, building dams, buildings, however, I will take U.S. Customary any day of the week.

Because a lot of the "Never Metric" types run into trouble when they go past the number three. We ARE a metric nation, and slowly but surely a sensible system of measurement is taking over.
Honestly, a Foot is the length of thirty-six barleycorns laid end to end? A mile is one thousand steps (Maybe if you're a Roman - and the Roman Mile is shorter than the Statute mile). And converting Acres into Square miles and then into Rods...? Make mine METRIC.

I am not really a never metric, but I do find attitudes like yours interesting. Does it matter to me what the definition of a yard or meter is? No, not really. You bash those other units of linear measurements but then what is the definition of a meter? The length of the path traveled by light in a vacuum in 1/299,792,458 of a second. Look at that fraction of a second, lets be honest it is just as ridiculous and arbitrary as any other measurement. For the record since 1893 the U.S. Survey foot is defined as 1200/3937 of a meter. Thing is once defined, for the vast amount of human activity what exactly that definition is derived from doesn't matter in the big scope of things. Not like Joe Schmo can accurately measure the speed of light in a vacuum in his garage.

I am glad you brought up land area, because acres is a great practical measurement for land. SI metric on the other hand is very unwieldy for land area. An acre is either 4046 square meters or 0.00405 square kilometers. So if you have a 0.25 or a 5, or a 40 acre lot (typical sizes in practical use) you have respectively either(roughly) a 1010, 20,235, or 161,870 square meter lot or a 0.001, 0.02, or 0.161 square kilometer lot.

I would argue the U.S. went the best route which is take the good of both U.S. Customary and SI Metric and allow us to use the better of the two in certain applications were the other is not as good.

#### GeorgeOrwellLives

Identity, politics and good, old fashioned resistance to change.

Why doesn't the US use the metric system? : Read more
There really is no compelling reason for the United States to move completely to the Metric system. As said by another poster, we do use both. Second, in the modern realm of technology, there is no inherent advantage to a system with a base1O over the current English measurement system used. And as explained earlier, the English system has more measuring points than Metric. 98.6 degrees, 32 degrees freezing and 212 boiling, 6 feet tall, there are natural and innate to Americans. Again, no compelling reason in the age of technology, where calculation is performed by calculators instead of humans, to change.

#### RobG

The use of the decimal for the system is vastly overrated. It makes sense for money, but in a physical measurement it is much easier and far more accurate to divide by two by the eye, as the US Customary System allows, than it is by ten. This matters in almost every measurement most of us make. Let the scientists keep their decimals. The carpenter and the cook have a better system.

The claim that it's "far more accurate to divide by two by the eye" is not supported and really can't be using imperial measures. Firstly, it's equally as easy to divide by halves using the International System of Units (SI units) as imperial. Half a cup is half a cup whether it's measured in fluid ounces or millilitres.

Using length, 1/4 kilometre is 250 metres whereas 1/4 mile is 1,320 feet or 2.5 chains. I know which of those is easier to work with. How about adding 3/8" and 7/16"? With SI units the division is always of a unit of 10 so the values are consistent, e.g. 1/4 litre is 250 millilitres, 1/4 metre is 250 millimetres, etc. so you just need to learn the decimal equivalents of say 1/2, 1/4 and 1/8 (0.5, 0.25 and 0.125 respectively) and you're got the common halves of SI units of measure.

Secondly, the imperial system is not designed to be easily subdivided by halves anyway. For example, the progression of length units is: 12 inches to a foot, 3 feet to a yard, 22 yards to a chain (which is also 100 links, making a link 0.66 feet or 7.92 inches), 10 chains to a furlong and 8 furlongs to a mile. So 1/2 mile is 2,640 feet, half a chain is 33 feet and half a yard is 1.5 feet or 1' 6". So the "divide by 2" argument just doesn't stack up.

The US uses SI units for electrical measures: volts, watts, ohms, etc. The basic imperial units are all specified in SI units and the US military and scientific communities use SI units. So the precedent is there, it's just that the US is weirdly conservative about certain things to the extent that use of imperial measures is viewed with a kind of religious righteousness and woe betide anyone who tries to change it.

#### RobG

…in the modern realm of technology, there is no inherent advantage to a system with a base1O over the current English measurement system used.
The "English measurement system" uses a variety of bases even within the same units, e.g. length uses 12 inches in a foot, 3 feet in a yard, 22 yards in a chain, etc. so the base varies with every different unit used. That's just asking for problems.

And as explained earlier, the English system has more measuring points than Metric. 98.6 degrees, 32 degrees freezing and 212 boiling,
That is somewhat spurious given units can be divided to any level of precision. The Celsius range of 0 to 100 can be divided into 0.001 degree increments if you like to give 100,000 gradations (and of course the same can be done with Fahrenheit).

6 feet tall, there are natural and innate to Americans.
How is the number "6" any more natural or innate than the number "180", which is roughly the number of centimetres in 6 feet?

Again, no compelling reason in the age of technology, where calculation is performed by calculators instead of humans, to change.
Except that it's humans that program the calculators and computers and can easily get it wrong, and not everyone wants to pull out a calculator to work out simple things like how many feet in 1/8 mile (660)? Whereas how many metres in 1/8 kilometre is 125 (1/8 litre is 125 ml, 1/8 kg is 125 g, etc.).

#### sarajo

The claim that it's "far more accurate to divide by two by the eye" is not supported and really can't be using imperial measures. Firstly, it's equally as easy to divide by halves using the International System of Units (SI units) as imperial. Half a cup is half a cup whether it's measured in fluid ounces or millilitres.

Using length, 1/4 kilometre is 250 metres whereas 1/4 mile is 1,320 feet or 2.5 chains. I know which of those is easier to work with. How about adding 3/8" and 7/16"? With SI units the division is always of a unit of 10 so the values are consistent, e.g. 1/4 litre is 250 millilitres, 1/4 metre is 250 millimetres, etc. so you just need to learn the decimal equivalents of say 1/2, 1/4 and 1/8 (0.5, 0.25 and 0.125 respectively) and you're got the common halves of SI units of measure.

Secondly, the imperial system is not designed to be easily subdivided by halves anyway. For example, the progression of length units is: 12 inches to a foot, 3 feet to a yard, 22 yards to a chain (which is also 100 links, making a link 0.66 feet or 7.92 inches), 10 chains to a furlong and 8 furlongs to a mile. So 1/2 mile is 2,640 feet, half a chain is 33 feet and half a yard is 1.5 feet or 1' 6". So the "divide by 2" argument just doesn't stack up.

The US uses SI units for electrical measures: volts, watts, ohms, etc. The basic imperial units are all specified in SI units and the US military and scientific communities use SI units. So the precedent is there, it's just that the US is weirdly conservative about certain things to the extent that use of imperial measures is viewed with a kind of religious righteousness and woe betide anyone who tries to change it.

as a british citizen & a user of the metric system Ive often wondered that myself

#### Mglass

It was a missed opportunity that the United States failed to change to the metric system in the 1970s, when Australia, New Zealand, Canada and most of the other Commonwealth countries changed.

Having experienced the metric changeover in Australia I can categorically state that it wasn't that big a deal. Yes, there were minor inconveniences, but even changing the road signs was not as hard as you might think. It took a while to get used to Celsius temperatures, but soon the Celsius measures felt just as hot (or cold) as their equivalent in Fahrenheit.

As for the old measures being more intuitive, that's nonsense! It's a matter of what you are used to, and what you are used to can also change over time.

GreatGooglyMoogly

#### sarajo

What I dont get is why dont americans refer to their weight in stone (st) & pounds (lbs)

for example I weigh 12 st 2 lbs (or 12.2

why do they just refer to their weight in pounds

Replies
0
Views
471
Replies
0
Views
69
Replies
1
Views
136
Replies
0
Views
127
Replies
0
Views
476