As a carpenter, I have mixed feelings about metric. While it’s truly easier to use, it would truly screw everything up. All of our materials are not only based on Imperial, the measurements of dimensional lumber made before the lumber is planed, yeilding a different finished measurment. Thus a 2"x4" is actually 1.5"x3.5". That would be
8.89cm x 3.81cm. Ok, so we adjust our stud sizes to 9cm x 4cm. Now standard stud spacing becomes 40.64cm oc, or say 40cm oc for simplicity. Hmmm, ya know that’s not so bad.
Sheet goods would have to change to 120cm x 240 cm to work with or 40cm spacing, which keeps them nominally 4’x8’.
Ok, so I stand corrected, it wouldn’t be so bad. The hardest part might be terminology, we’re so used to 2x4’s. It would be nice if lumber was actually close to the “named” dimension.
Decimal notation. This isn’t a big advantage, it’s prefectly simple to pick a unit in Imperial and go with decimals from there.
Basis of units. The metric system is structured so that the units align with basic scientific ideas. Water has a density of 1 g/cc^3 at STP. Water freezes at 0, boils at 100. And so on.
Imperial/American has one big advantage for the average joe. Its unit system is based on common every day uses. Pints/cups/tbsps etc relate to ratios commonly used in cooking. The Farenheit scale is 0 when it feels really cold, and 100 when it feels really hot. And so on.
As numerous others have pointed out, SI has only one significant advantage in the real-world, ease of calculation.
BUT, this advantage is far less significant today then it was forty years ago, due to the universal availability of calculators and computers.
In some relatively specialized fields, as noted above, this is still an advantage. However, to the average person, the demonstrated advantage of SI over English no longer outweighs the hassle of switching.
Very important observation - the differences between “four inches = 100mm” and “four inches = 101.6mm” (or whatever it is) are irrelevant if you’re familiar with three-milimetre errors and margins.
Laptops and computer monitors are only ever measured in inches. Most pubs will have pint glasses and they are becoming more popular in Australia. Most people will also know their height in feet and inches and will be more likely to express in it in that form. Engine cylinders are only ever bored out in thousandths of an inch and for the bigger, muscle cars, the motors’ displacement is expressed in cubic inches. Granted, the newer models will be in litres but petrol heads will more often deal in inches. Tyres’ widths are in mm but profile is in inches. Rifle calibres are most likely in inches and shotguns are always in gauge which is based on the pound. My ex-girlfriend’s father (farmer), and most of the people I met through him, often spoke in chain (22 yards) and, of course, a cricket pitch will always be that length. Graphic designers are more likely to use points or even picas than mm for font sizes (although mm for other measurements) and sub editors still use column inches.
I’m sure I can think of dozens more.
I think the reason America hasn’t completely changed to metric is inertia. The immensity of American industry would make retooling, retraining and changes to curricula an enormous undertaking. In comparison, it was trivially easy to switch Australia or even the UK over. The problem is, making this change will only get more difficult as the mass of American industry and culture increase.
As some have pointed out, it has another significant advantage: that it’s a world standard. Americans are at a disadvantage for having to convert all units when working with foreigners. Trying to maintain two units is, as already pointed out, expensive and annoying.
The other day I was working on my bicycle and needed some new screws. It’s an American made bike with mostly American components, but the worldwide bike industry is mostly Metric so it has Metric screws. (Japanese parts are often used on American bikes, and vice versa). I couldn’t find the appropriate Metric screws at local hardware stores! When I was in Japan I never had this problem - since the hardware stores there only need to stock Metric parts, there was a huge selection of Metric screws. (The exception is 1/4" size which has become standard in some industries, e.g. tripod holder on cameras.)
Another thing about a worldwide standard: there are no variations. A gallon can be 3.785 liters or 4.546 liters depending on where you are, and an ounce of gold weighs more than an ounce of feathers (gold is measured by troy ounce). But a liter is the same amount everywhere you go. A gram is a gram whatever you measure.
Do you actually use a unit-free version of Maxwell’s equations? Don’t you need to use units where c=1? I’ve never used anything other than the SI and CGS versions, which look very different from each other. (See here - there’s a CGS version at the bottom.)
As I’ve said a hundred times - it only seems that way because you’re used to that system. Whatever unit system you choose, you need several different units for each type of measurement, and you aren’t going to find one set that’s inherently suitable for “common every day uses.” Take length, for example - screw sizes must be measured in fractions of inches, small objects in inches plus fraction, human height in feet plus inches, building and vehicle sizes in feet, and travel distances in miles. In metric you’d use millimeters, centimeters, meters and kilometers. Neither set is significantly easier than the other. The latter has the advantage that combining units is easier.
If converting one scale to another is not an important part of the task, then non-metric measures are just fine. If you’re building something, as long as you keep with the same measures, there is no point at which the metric advantage rears its head.
The Imperial system seems pretty abitrary, but it has what I’m going to call “deep utility”. It has hung around this long because there are tricks and the odd coincidence that make working with wood, steel, and other common engineering materials easier. Talk to a craftsman, they’ll know these things… carpenters in particular.
Metric, OTOH, is based on what? Multiples of ten? Water? Metric stock materials in nice round dimensions don’t have nice round physical properties. So you end up with weird metric dimensions, defeating any of the “ease of calculation” benefit.
I’m sure any craftsman in Japan can tell you the equivalent tricks in Metric.
Metric is based on the decimal system which the entire world has already converted to, including the US. All math taught in school is decimal. All calculators sold in stores are decimal. The English language (and Arabic number system) doesn’t even have symbols for 10 and 11. (I know you can use A and B, but nobody writes “I’m 5’A” tall".)
Heck, my husband doesn’t even put a coat on until it’s in the teens.
The only time I’ve put a coat on to run the garbage to the curb was a day of -3 F with a windchill of -15. Now that is cold. Instant ice cream headache with every breath.
That’s you. I live in Michigan. The state of whether water outside is frozen or liquid to me is important. When I know from the temperature in Celsius that it is negative, I then immediately understand ice forming on the ground is a concern, and that precipitation from the sky will likely be in the form of snow (ick) rather than rain. And when the temperature is predicted to be in the double digit negative range, not only is ice an issue but it will feel “really cold!” And when temperatures are forecast in the positive single digit range, it’ll be just “chilly”, but not significantly cold. Positive double digit temperatures mean that temperatures no longer are in the uncomfortable range at all.
Weather forecasts in winter around here never mention negative degrees. It’s just understood that they all are. Most often they would be even if they were degrees F.
