Metric (SI) vs. English (Imperial)

Jim the Cro-ster over at Physics is Phunnner than Phlatulance remarked today on the metric vs. english dichotomy of U.S. society and its implications for daily use.

I agree with his main thrust, that in order for something to be useful, it must be used. i.e., to really grok a measurement, like the meter or centimeter, you need a visceral understanding of its magnitude. I can pick up a object and guess its weight in pounds within 10% as long as it’s not too heavy. I can’t do that in kilograms without first doing the pounds and then converting in my head. Same with meters, although I’m better there, and despite my work, I’m absolutely crap with kilometers per hour.

It’s all about familiarity. During college, I worked with metric (SI) units the majority of the time while taking engineering classes. I heartily detested any moment where I was forced back upon english (imperial)1, but as Jim mentions, we didn’t do any familiarization with the metric units beyond our calculations. It wasn’t until I entered the workplace and started boring holes in things, or now building roads, than I started applying numbers to real world objects2.

So, I know exactly what it’s like to have a four 12′ lanes with a 32′ median, perhaps a 10′ shoulder. In metric, that’s…ummm…3.6 meter lanes with a 10 meter median and 3 meter shoulders? I just don’t think in meters, and I’m trained! What do we expect of the rank and file grocery shopper who only cares about how much that gallon of milk costs, not the fact that instead of $3.99 per gal, it’s $1.05 per liter. What the hell is is a liter anyway?

In an interesting bit of history, the U.S. Federal Highway Administration tried to do a conversion from imperial to metric back in the 90′s. The intention was to have a 5 year switchover and then all federally funded projects would be required to be metric. This crashed and burned due to politics. Amusingly (if you have a macabre sense of humor), this has made it more difficult in the long run to pursue metrification in the highway industry because so many people have bad tastes in their mouths about the on again off again metric switch. A lot of highway projects were caught in the middle, had to be converted from imperial to metric, then ended up being converted from metric back to imperial3. Many decision-making highway engineers and officials were in charge of projects that got mangled in this fashion and have a severe distaste for any FHWA-mandated switchover.

The upshot is, the U.S. remains the only first-world country to not have officially adopted the metric system. We maintain this high-horse with the company of two other leading countries, Myanmar and Liberia.

Should we convert? Yes. Will we convert? Not in the next ten years.

1: yes I know there’s a difference between Imperial and U.S. Customary Units. I’d rather type “imperial” though.
2: let’s not forget the time I spent working in feet, inches, and sixteenths while doing wood projects at home.
3: this is a difficult process, not nearly as easy as you might think.

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11 Responses to Metric (SI) vs. English (Imperial)

  1. James Cronen says:

    Funny, out of all the disciplines of engineering that still adhere to the Imperial system, I forgot to mention traffic engineers as the number one perpetrators.

    I agree with you that I don’t think we’ll see a changeover in the next ten years. In fact, I don’t know that we’ll ever actually see another actual formal governmental push to go metric, due to the aborted attempts in the 1970s and 1990s.

    We’ll just continue our slow creep toward metric. Right now the standard sizes for soda bottles are 20 ounces and two liters, so most people have a rough idea of what a liter is. Engine displacements are measured in liters or cubic centimeters.

    Britain uses metric for just about everything except for speed limits. Maybe insisting that the public accept that speed limits are 110 km/h instead of 65 mi/hr is barking up the wrong tree.

    As we globalize, metric will slowly gel into place. Looking back we’ll have wondered what all the fuss was about.

  2. Steve says:

    Don’t forget the massive number of laws that would have to be changed, including (but not limited to)…

    Speed Limits: Right now, the Georgia code only quotes maximum allowable speeds in MPH. For instance, 55 MPH is the maximum allowable speed limit on any 2-lane highway in the state. The law
    would have to be altered to change 55 MPH to its approximate metric equivalent of 90 km/h. (Fortunately, Federal MUTCD does have specs for metric speed limit signs if such a changeover should occur.)

    Fuel Taxes: The rates would have to be changed from “per gallon” to “per liter”.

  3. Bill Ruhsam says:

    @Steve: That’s the beauty of laws, you may just alter them by adding additional ones that say (basically), “follow seciton 4.2.3 except that all references to mph shall be as follows in kph…:”

    I hate going through state codes and trying to find all the little exceptions and “buts” and other items that affect things.

  4. phil ashbrook says:

    One must under stand what the french had planned with time , as far as I can tell it was to eradicate God from everything , the ethiopians
    have it right , the universe is not metric.
    We used to use what is around us for comparison , the metric people
    originally wanted a ten day week , a ten month year with the days left over for atheist holidays , and time itself would have to change forever . no 7th day of rest , God would would be taken from your own mortal lives , Imperial has style like our use of langauge ,dont let it be dumbed down .I saw a funny thing on TV when a German said the Mileage on his car was low , there was no metric way of saying it .Imperial is deeply imbeded in the English language . If I’m
    wrong the world should be speaking French .

  5. phil ashbrook says:

    Sorry , they wanted a 12 month year with 5 days left over , but still a 10 day week ,30 day month .

  6. Bill Ruhsam says:

    @phil. I don’t think god really cares what measurement units we use. So besides any (possible) anti-god aspirations the metricarians had in the 1700s, having a logical system of units only makes life easier. No one is saying that you can’t hold on to imperial (either English or Roman) for style sake, just that it shouldn’t be the primary means of communicating length, mass and time (and charge, temperature, and luminosity).

    Also, I don’t think Reagan axed the metrification budget item because he thought that we were attacking god’s plan.

  7. phil ashbrook says:

    Ok Bill I know what you are saying , reagan did what he did ,Australia thought nixon was going to do it and bloody went metric , I dont think Obama will do it , but metrification of all things is the general aim,
    When it comes to time keeping for the planet I start to find the whole thing funny, I started to read what was being proposed , metric time is mad it would take hundreds of years to change the whole planet ,and many many years for the planet to think of the names of the divisions .The one thing I’m glad of is music can never be made metric . Long live number 12 ! .

  8. Bill Ruhsam says:


    The one thing I’m glad of is music can never be made metric . Long live number 12 ! .

    I bet somebody has tried, though!

  9. phil ashbrook says:

    I’ve been thinking on this , if the metric minute had hundred
    seconds , it would be longer than our current one , if A 440{ that is the oscillations per current second } would be a higer number and not a very round number at that , as the second is based on earths orbit time then music might on really apply to that , so metric music
    would sound out of key on just the one note , I have 12 frets on my guitar between octaives , the sub-divisions being natural nodes that I
    would think apply throughout the universe , how on earth could you make a natural thing metric , even the sun oscillates in a very very low key of B . then we have to find an atom that oscillates in the right way for our metric atomic clock , I must stop now my minds gonna pop .

  10. Aline says:

    I took some Mechanical Engineering classes a while ago and remember one professor indicating that at small measurements, metric becomes extremely difficult to work with. Since metric is always divided by 10 it makes things dicey when trying to deal with portions of a millimeter. Especially in the application/manufacturing – calculations are generally easier in metric. I can picture 1/4, 1/8, 1/16, and even 1/32 or 1/64 of an inch. I can not imagine a ruler that has a metric measurement smaller than a millimeter. Does anyone know how mechanical engineers handle this in countries that use metric?

  11. Bill Ruhsam says:

    I worked on a job that had both metric and english parts rolling about the job floor. If I recall correctly, we just measured in tenths, hundreths, and thousandths of millimeters and/or microns. Just depended on the equipment. Everything was digital readouts, calipers or micrometers anyway so you had to know what you were reading to know what you were measuring. Once you get used to it, you can eyeball a slot or a measure in the .01 inch range pretty closely.

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