The metric system: Make your case for it and why we should switch to it. (As if we haven't already)

Before I start here is a very informative video, complete with interview from Dr Steven Mihm of the University of Georgia. A historian specializing in standards.

First off, I’d argue the American unit is more intrinsic. It has more factors:

1, 1/2, 1/4, 1/8, 1/6, 1/32

Try doing that with a base 10 model in your head:

1cm= 10mm, 1/2cm= 5mm, 1/4cm= 2.5mm, 1/8cm= 1.25mm, 1/6cm= 0.625mm, 1/32= 0.3125mm

As far as switching to the metric system, I’d argue (as they do in the video) we already have. The medical industry uses it almost exclusively. Take a look a your prescriptions for example. It’s in metric. Pastry chefs are also goin metric.

I won’t argue that the American custom unit is better, it’s just more intrinsic.

And I’m also not sure how different America would look if it “switched” to metric than it does today.

So the debate I’d like to have is: Is it worth it to officially switch? And if so, what does that actually mean? And how much money should be invested in such an endeavor?

Any discussion about widespread conversion to metric is totally academic, given Trump’s 46.9% of the vote. The concept is too foreign for the population.

Hell, Congress tried banning metricizing the federal highway system as recently as '93.

The case for a standard system is, everybody uses the same system. This may take on some importance if you are going to exchange specifications, tools, research, etc. with anyone outside America. In fact, that is why there is an international system of units today, to remedy the hot mess that went before.

I do not buy this claim, but rather than get into the nature of American units (versus proper Imperial and/or Chinese units :], I put it that this is not the point at all, standardization is.

Do you have examples where this is currently a problem? I work in in manufacturing and we use metric, bc our product is global. Which backs up my earlier statement that for all practical purposes, America already has gone metric.

I assumed you were proposing that American units are “intrinsic” and therefore manufacturers and engineers should be using them instead.

If “for all practical purposes” America uses normal metric units, then there is not much left to switch that would require an endeavor and cost an impractical amount of money, is there? Replacing Federal highway signs, for instance, certainly costs something, but they need regular maintainance anyway.

ETA some real cost may enter when re-certifying critical specifications, tolerances, etc. It may not be enough to multiply all the units by a conversion factor and call it a day. I would not trust a crude approach.

Yeah, I started the thread bc I get annoyed at people saying, (which I’ve heard on this board recently) “Gah! America needs to go metric already!”

In what possible sense is powers of two more “intrinsic” than powers of ten? I think that word does not mean what you think it means.

The fundamental improvement of SI (“metric” was shut down decades ago in favor of SI) over customary US (or the prior various sets of British) units is that the various units for different things e.g. length vs volume are deliberately designed to mesh together.

E.g. meters & liters fit together logically mathematically. Feet and gallons have no connection whatever. That is the secret sauce of SI. Not the powers of 10.

Although having a uniform powers of 10 system for all multiples of all types of units further improves the logic and the likelihood that calculations won’t fail for brain fart reasons. Said another way, it’s designed for success, rather than being a happenstance briar patch of traps for the unwary or incautious.

This gloriously misses the point. A decimal system is not just a clumsier way to write down the mess of arbitrary fractions that you are accustomed to. You don’t use standard sizes that are expressed concisely in arbitrary fractions in a decimal system. You use standard sizes that are expressed concisely in the specific fractions that are the basis for the system - factors of ten. Which makes things vastly simpler to manipulate.

Add up 5/8 + 3/16 + 1/32 in your head.

Now add up 0.6 + 0.2 + 0.03 in your head.

Why are those more intrinsic fractions than
1, 1/2, 3/10, 1/10, 1/20, or 1/100

If you do anything involving scientific notation or engineering, metric is much easier. For the same reason figuring out the value of a handful of coins is easier now than adding up half-a-crown, a shilling and tuppence (where a pound was 240 pence IIRC).

I work in picas and points. :slight_smile:

So converting back and forth with inches is easier for me.

The OP has it all backwards. Right now the USA spends vast amounts of money being as non-SI as they are. Everything would get cheaper once we fully embraced SI as the system, not a dual system. Or the one we have now where vast swathes of everything is specced and manufactured in SI, but in problematic SI sizes & quantities that match round customary units and are then mislabeled in customary units to avoid upsetting the customer proles.

Would there be some one time conversion costs to be amortized against the savings over time? Sure. But they’re trivial compared to the costs baked into doing things the dumb way we do them now.

Had our parents gotten serious about this back in the 1970s when we had a decent chance those costs would long since have been earned back and it’d be pure profit from 15-20 years ago. So “Should we bear the pain of conversion?” is another way of saying “Should we continue beating our head against the wall; we’re used to doing that so it feels familiar & comforting. Stopping sure seems dangerous.”

No conversation about various standards is complete without this learned reference:

Good point. I didn’t think of that.

My case for it: It would have saved one of our martian probes.

It also makes it far easier to apply tolerances and track significant figures in calculations; hence why all science and engineering (other than some civil and architectural engineering) is done either in SI or in decimal inches aside from historical units such as horsepower, British Thermal Units (BTU), and pounds (both, confusingly, force and mass, leading to the off-seen errors by factors of 32.18 or 386.4, depending on the units of acceleration).

The intuition argument which is always put forth in favor of the Imperial and US Customary System of units is utterly nonsensical; not only are these made up divisions frequently based upon some arbitrary measurement like the “size of three grains of barleycorn”, the traditional applications that most units were developed for—primarily agriculture, surveying, and nautical measurements—are not even applicable to common use in science, engineering, construction, et cetera. One oft heard claims is that the Fahrenheit temperature range is preferable to Celsius because of the finer divisions, as if anyone can tell the difference in air temperature between 72 °F and 73 °F; in fact, Celsius makes far more sense because the steps in °C are at least close to what a human can detect notwithstanding a scale based upon the freezing and boiling points of water at standard pressure actually has applicability to the everyday world.


Routine Maintenance works when you’re upgrading to better reflectivity, longer lasting signs, etc. They don’t all have to be upgraded at the same time, just as they wear out.

It doesn’t work when you’re changing the content of the signs, like speed limits and mileage. You can’t have a stretch of highway with a speed limit of 60, and then the same highway goes up to 100, and then further on it goes back to 60.

I remember when Canada went metric. My brother and I were driving to university, and all along the highway, crews were out applying stick-on “100” signs over the former “60” signs. And that was going on all over the province that day. That was a massive cost. The same thing happened in other provinces. I can’t remember if it was the entire country switching on the same day, but it was pricey.

I sometimes drop into metric units just because how convenient the conversions are.
1 Liter of Water = 1 Kilogram
1 Cubic Meter = 1,000 Liters

Some of the units used in the US of A are just rote memorization:
1 Mile = 5,280 Feet
1 Acre = 128’ by 128’
3 Teaspoons = 1 Tablespoon

The only thing I’d defend is that Fahrenheit was deliberately designed by people for people; 100F is HOT, 0F is COLD. But Fahrenheit was a lot later than the other English units.

Honestly, switching to metrics would probably mean familiar units are kept in new form. A Mile is now “1 1/2 KM”, one ton is 1,000 KG, and a gallon is “5L” (Because, logically, this is our chance to supersize something forever). And part of the reforming may very well be looking at the speed limits, and replacing 70 MPH with 140 KPH.

Now if we could just get to the part where nutrition labels list a per gram and per container spread instead of the bizarre American custom called a ‘serving’, which should be ruthlessly burned to the ground and the earth salted beneath it.

You only have to look at the UK to see how a hybrid system can work.

Speed limits and distances are shown in miles. The fact that a mile is 1760 yards doesn’t matter at all when you are referring to the distance to the next town. Footpath signs are metric, so if I walk to the park, it’s 1k, but ½mile if I drive.

Loose and packaged food is sold by metric weight. I happily buy 200g of ham, or a litre of cola, but, and this is where the anomalies come in, I buy fresh milk and draught beer in pints. (I think it’s only fresh milk and beer that are exempt)

I only need one set of metric spanners to work on my car, although I do have some odd sizes for the older plumbing in my house.

It’s really moot as precision can be obtained in any system by measuring each degree by tenths (22°C → 22.0°C)

You probably just have the reverse problem that I have. The standard I refer to now is:

100C - Boiling (212F)
40C - Hotter than Hell (104F)
30C - Hot (86F)
20C - Warm (a.k.a. Comfortable) (68F)
10C - Cold (50F)
0C - Freezing (32F)

Fahrenheit’s system used to feel completely random (no numerical points/markings that made sense) but dividing it by a few 10 degrees of Celsius and using familar language helped me out.

I’ve never understood how people can find Celsius difficult. 0 is the freezing point of water and 100 is the boiling point. T-shirt weather is at around 22. Done.