Al Williams wrote up a seemingly innocent piece on a couple of rules-of-thumb to go between metric and US traditional units, and the comment section went wild! Nothing seems to rile up the Hackaday comment section like the choice of what base to use for your unit system. I mean, an idealized version of probably an ancient Egyptian’s foot versus a fraction of the not-quite-right distance from the North Pole to the equator as it passes through Paris? Six of one, half a dozen the other, as far as I’m concerned. Both are arbitrary.
What’s fun, though, is how many of us need to know both systems and how schizophrenic it all can be. My favorite example is PCB layout, where tenths and thousandths of an inch are unavoidable in through-hole and surface-mount parts, yet we call out board sizes and drill bits in millimeters – on the same object, and without batting an eye. American 3D printer enthusiasts will know their M3 hardware, and probably even how much a kilogram weighs, because that’s what you buy spools of filament in. Oddly enough, though I live in Europe, I have 3/4” thread on my garden hose and a 29” monitor on my desk. Americans buy two liter bottles of soda without thinking twice.
The absolute kings of this are in the UK, where the distance between cities is measured in miles, but the dimensions of an apartment in meters. They’ll buy gas in liters and beer in pints. Humans are measured both in feet-and-inches and centimeters, and weighed in pounds, kilograms, or even stone.
And I think that’s just fine. Once you give up on the rightness of either system, they both have their pros and cons. Millimeters are superb for doing carpentry in – that’s just about how tight my tolerances are with hand tools anyway, and if it’s made of wood, you can fudge 0.5 mm either way pretty easily. Sure, you could measure in 32nds of an inch, but have you ever bought a plywood sheet that’s 1536 x 3072 thirty-seconds? (That’s 4’ x 8’, or 1200 mm x 2400 mm.) No, you haven’t.
But maybe stick to one system when lives or critical systems are on the line. Or at least be very careful to call out your units. While it’s annoying to spec the wrong SMT part size because KiCAD calls some of them out in millimeters and inches – 0402 in inches is tiny, but 0402 in metric is microscopic – it’s another thing entirely to load up half as much fuel as you need for a commercial airline flight because of metric vs imperial tons. There’s a limit to how units-flexible you want to be.
Don’t forget car tyres: diametre in inches snd width in millimetres.
Being an old git who went to school just as the UK went metric means I’m happy with either system. In fact, more than once, I have measured something in metres, then added a couple of inches…
Thanks for using metre.
Somehow related and nice to have bookmarked:
https://www.youtube.com/watch?v=pM3c328VifA
Being a Brit, I can have a meter that measures metres…
Round here I’ve been known to use the meter to measure aluminum for my specialized infrared aluminium shielding without the proper authorisation. Used a few zeds here and there too but like to keep things centered by using millimetres for the small stuff and feet when I need to measure without a ruler. It just depends.
Don’t forget about dreams… https://www.youtube.com/watch?v=JYqfVE-fykk + https://www.youtube.com/watch?v=VJ62EfUKI3w
You mean ‘tires’ :) .
In the UK, “tire” means to get weary. “Tyre” really is the rubber surround on the rim of a wheel. Try it, mixed vocab adds nuance.
e.g. a program is a sequence of instructions a computer executes; a programme is a plan, described verbally (e.g. a theatre programme or a broadband rollout programme).
or, e.g. a disk is a formatted, magnetic media; a disc is an object you might throw or contains analogue optical digital data (like a CD).
People who consider Bud Light to be a beer do not get to mock anyone else’s beer, sit down.
diameter
Rulers and measuring tapes in the UK, have metric down one side, and inches down the other.
The other day I was trying to find the centre of several bits of wood, for one I used metric, and another I used inches, purely on what made the numbers easier.
No we don’t, we buy petrol in litres!
“.. and beer in pints.”
And the pint is a different size — 20 fluid ounces as opposed to 16.
Here in the UK I once bought 2 metres of 1/2 inch hose.
And Gas in kilograms
And we don’t weigh people in pounds! Only is stone & lbs (or lbs and oz for babies). We Brits have very little concept of whether a 300lbs person is fat or skinny. But tell us it’s 21 stone and we know.
what amuses me endlessly is europeans mocking Americans for using multiple metrics when you cant travel more than a few hundred miles in any direction in europe without needing a whole new language, Either develop the flexibility to be polymetric or ditch your legacy languages and speak Metrican.
TolkienUnits.
I’ll, reply to your comment after I finish Second Breakfast…
Metric is the standard around the whole globe, apart from the US and … is anything else left? So, you can include basically every human language speaks the universal language of physical units.
Well, actually it’s not the standard in the English speaking world. Every English speaking country except the US uses a mix of imperial (often with their own definitions of certain measurements like pints) and metric in daily life.
The USA does not use Imperial. It uses US Customary, which is not the same. The three main systems are the US Customary Metric, SI the French metric, and Imperial the Commonwealth metric. The base reference measures for the US Customary metric are part of SI. The inch is exactly 25.4mm. The design of SI has some serious shortcomings but it is the system adopted by the US Congress in 1895 as the official reference system for the USA. The US had joining the Metre treaty in 1875 and there were 20 years of refinements tot he system before adoption.
MKS is popular today for SI but there are plenty of older books and papers that entirely use CGS + Angstroms. I think if you find an early 1960 Halliday and Resnick Physics, when it was one very thick book, you will find CGS is the standard, plus plenty of pounds and slugs and feet. I don’t think you will find “boost”.
There are always fascinating comments on this topic, by people who are quite comfortable regularly using half a dozen computer languages. Go figure.
Metric is the standard around the whole globe. The US is metric. It just uses weird units derived from them.
Complaining about ISO fasteners vs SAE (ok not really SAE but you know what I mean) fasteners is different. That’s a standards body, not a reference, and that’s just a function of US industrialization happening faster than the rest of the world (since they were busy trying to kill each other). SAE fasteners now are still metrically defined.
It’s like complaining about Philips head vs square drive or Torx.
No, we don’t mock you for using multiple metrics. We mock you for using imperial. Period.
Canada is in the same dual world can’t make up mind situation. We measure speed and distance in kilometers, gas in liters. But everything related to real-estate is in Sq ft, most grocery items are in lb (pounds). All hardware you get in homedepot is freedom unit too.. You can’t really buy a metric drill set if your life depends on it!
Funny thing about the drill bits is that here in the states it’s easy to find a metric drill set!
Don’t mention Canada… We had to buy square ended screwdrivers just to open a packing crate from a Canadian supplier! We haven’t used it since :-D
Everything is better than a Philips screwdriver, though! ;)
All the grocery store labels I see are in both. Ads are often in imperial only, such as $6.99/lb ground beef.
One of the things drilled into my head as an engineering undergrad was unit analysis. Write down all of the numbers and their units. Cancel out units and make sure you end up with what you expected.
Oops, not quite right. With good old English Engineering units you will probably need to throw in a g sub c somewhere.
This reminds me of how the Mars Climate Orbiter was lost: NASA used metric, while Lockheed Martin… did not.
https://en.m.wikipedia.org/wiki/Mars_Climate_Orbiter
There have been many mishaps (or near ones) due to mixing of measurements besides the Mars Climate Orbiter…the one that stands out for me is the Canadian Gimli Glider. Luckily there were no fatalities but still a heroic effort comparable to Captain Sully’s landing on the Hudson.
Gimli Glider – Wikipedia https://share.google/aa5jD9WmMjS3atDXO
There are catastrophic mixups within systems as well. Consider the tragic Final Tap Mishap!
“0402 in inches is tiny, but 0402 in metric is microscopic”
“Inch” is a unit of measure. “Metric” is not a unit of measure. “0402” is from a numerical representation system of which I have hitherto been unaware and sadly I do not understand it. 402 inches is large, and 402 mm is forearm-length so that’s not it.
Plywood: 4ft x 8ft 1.2m x 2.4m Problem solved.
Metric, like Imperial is a system of measuring units.
https://en.m.wikipedia.org/wiki/System_of_units_of_measurement
What “0402” Means
– Imperial system:
– Length: 0.04 inches or 40 mils if you like
– Width: 0.02 inches/ 20 mils
0402 package is a specific SMD thing; that’s 40 thou by 20 thou, or quite small.
metric 0402 is someone getting pissy that how dare there be legacy units here, so let’s redefine the same numbers to mean something different, and that’s 400 micron by 200 micron. They least they could have done to avoid ambiguity is the same thing they do with bolts, precede it with a capital M.
Thank you!
“is the same thing they do with bolts, precede it with a capital M.”
The person who started calling SMD packages via their metric measurements without distinguishing it needs to be publicly humiliated. Sooooo dumb.
You don’t use centimetres or metres when measuring hardware – millimetres only.
Your 8’x4′ is 2400×1200. Millimetres is implied, and you only work in whole numbers.
I agree that both systems are arbitrary but no, the imperial nowadays only have cons because the pro is that almost everyone else have converted to the French units. And yes, it requires a transition period (which we had about 100 years ago), so the sooner the better. Just ask NASA if keeping both systems around is a good idea, even if the science community has formally embraced SI units
Divide a meter into thirds cleanly.
Base12 has its advantages in the number of factors in the base. It may be unfamiliar, but it is way more useful for building something without a computer model.
https://www.youtube.com/watch?v=pqGyUvZP0Zg
I’ve always found this an odd argument: it kind of depends on you using small integer numbers of largeish units, which falls apart as soon as you do the division.
The answer of course 333mm (which I can do in my head), which for any task you’re doing by hand meets or exceeds the tolerance you’re working to. I can measure 333mm about as accurately as 12″ +-1/16. But to take your point further: dividing 1m into thirds is 333mm. In imperial that’s 39 3/8″ divided into 3 which is 13 1/8″, which isn’t harder but not really much easier either.
Finally of course things like wooden boards are usually 2400mm in size, which has many factors including all the ones favoured by the imperial system, plus 10 and 5.
One smaller disadvantage of the imperial system is it can’t seem to make up its mind for smaller sizes: is it power of 2 fractional inches, thousands of an inch, or that strange numbering system for small holes and screws?
The huge disadvantage of the imperial system is that unit conversions are much more difficult because there’s no relationship between, say, inches and pints.
1ml is one cubic centimeter. The other neat thing is that air, water and steel have densities of roughly 1, 1000 and 10,000 kg/m^3, which makes estimating rough weights from measurements very easy.
Force is in N, power is in W. The conversion factor is speed in m/s. What’s the conversion factor from lb-f, and feet per second to HP? And then if you need to somehow need to get rid of the waste heat from that process, you need to convert that to BTU/Hr.
The imperial folk don’t get that you only ever work in millimetres, using other units is amateur hour.
So the correct question would be divide 1000 by 3, and if you can’t figure that out then maybe put the saw down.
Rational arithmetic is exact. 12 is commensurate with 2, 3, 4, and 6 which makes the arithmetic relatively easy. 36 is commensurate with those and more. 10 is commensurate with only 2 and 5, which is why you get so many fractions with repeating decimals in base 10. Imperial rulers can be made by folding. SI rulers not so much. Step sizes that are factors of 10 are far too big. My ‘scope uses steps in the order 2, 5, 10, 20, 50, 100….. because?
Being exact is only relevant if you do cumulative addition or subtraction where the error could stack up.
But in engineering and design that’s explicitly discouraged: all your measurements should be relative to the same reference point and not to each other, to avoid stacking tolerances and error, because in the real world you cannot be exact even if you did measure things using rational arithmetic.
Agreed.
I was just watching an imperial vs metric video, and they were talking about buying lumber in mm, and the lumber they showed was marked 38×89. Bro, that’s just a 2×4 with a different stamp. And a 2×4 isn’t even 2×4.
yeah i don’t understand how metric countries do common construction trades. it’s possible to buy larger sizes here but generally everyone has 4ft x 8ft sheets of drywall or wood board. you put your studs / joists on 12″ (4x per 4ft), 16″ (3x) or 24″ (2x) spacing. one sheet is the height of a room, or on its side it’s half the height.
it is just so handy that 8ft is a nice whole number to define the typical ceiling height, and 8ft/96in can be divided easily into segments that are a whole number of inches too. even roof pitches….6/12 roof is just easy to think about (hard to convert into degrees though)
Unit schizophrenia goes at least as far back as the definition of the HO train gauge, where 1 foot maps to 3.5mm, making it 1/87th scale. (HO, of course, stood for Half-Oh (or Half-zero) gauge, which would be 1/96th if done only using Imperial units.)
“it’s another thing entirely to load up half as much fuel as you need for a commercial airline flight because of metric vs imperial tons. There’s a limit to how units-flexible you want to be.”
Those are close enough the flight would have been fine. The problem with the Gimli Glider was they pumped XX pounds of fuel instead of XX kg.
I’m born and raised in the US and ever since I’ve used the metric system in technical and hobby pursuits, I’ve felt that the Imperial system is one of the dumbest measurement systems possible. I mean, FRACTIONS? Really?
Grok agrees. It took it 1.1 seconds to formulate its reasons why.:
Describe by listing various imperial measurement units how stupid that measurement system is.
Grok 3 AI:
The imperial measurement system, rooted in historical British units, is often criticized for its inconsistency and complexity compared to the metric system’s decimal-based simplicity. Below, I list various imperial units and highlight their quirks to illustrate why the system can feel convoluted and, frankly, a bit absurd:
Inch: A small unit of length, roughly the width of a thumb. Sounds simple, but it’s part of a base-12 system (12 inches = 1 foot), which makes scaling awkward compared to metric’s base-10.
Foot: 12 inches. Why 12? Historical arbitrariness tied to human body parts or ancient standards. Dividing or multiplying requires mental gymnastics (e.g., 3 feet 7 inches + 2 feet 9 inches is a headache).
Yard: 3 feet or 36 inches. Used for slightly longer distances, but its relation to other units feels random. Why not just stick with feet or jump to miles?
Mile: 5,280 feet. Not a round number, not intuitive, and derived from Roman measurements (mille passus, thousand paces). Compare that to a kilometer (1,000 meters, clean and clear).
Furlong: 660 feet or 1/8 of a mile. Mostly obsolete, but still used in horse racing. Why keep a unit tied to medieval plowing fields?
Chain: 66 feet, or 1/10 of a furlong. Used in surveying, but who decided 66 was a good number? It’s niche and clunky.
Pound (lb): A unit of weight, but it’s 16 ounces, not a round 10 or 100. Converting to tons or ounces involves odd fractions.
Ounce (oz): 1/16 of a pound for weight, but also a fluid ounce for volume (different!). A fluid ounce is ~29.57 milliliters in the US, but ~28.41 in the UK. Same name, different sizes—confusion guaranteed.
Stone: 14 pounds, used for body weight in the UK. Why 14? No clear reason, just tradition. It’s not even widely used across imperial systems.
Ton: In the US, a short ton is 2,000 pounds. In the UK, a long ton is 2,240 pounds. Same word, different values. Good luck shipping internationally.
Gallon: 128 fluid ounces in the US, but the UK gallon is ~20% larger (160 UK fluid ounces). Ordering a gallon of milk? Better specify your country.
Quart: 1/4 of a gallon, or 32 fluid ounces (US). Useful, but why not just use liters, which are universally consistent?
Pint: 1/8 of a gallon, or 16 fluid ounces (US). Again, the UK pint is different (~20 fluid ounces). A pint of beer depends on where you’re drinking.
Fahrenheit (°F): Temperature scale where water freezes at 32° and boils at 212°. Why those numbers? Based on a mix of human body temp and arbitrary reference points. Celsius (0° freeze, 100° boil) is far more intuitive.
Acre: 43,560 square feet, or the area a yoke of oxen could plow in a day. Historical, sure, but wildly impractical for modern calculations compared to hectares (10,000 square meters).
Bushel: A volume measure for crops, ~35.24 liters in the US, but weight-based for specific goods (e.g., 60 pounds for wheat). Varies by commodity, making it a nightmare for consistency.
Teaspoon/Tablespoon: 1/3 tablespoon = 1 teaspoon, and 16 tablespoons = 1 cup. Kitchen measurements are a mess of fractions, unlike metric’s milliliters.
The imperial system’s reliance on non-decimal conversions (12s, 14s, 16s, 5,280s) and inconsistent unit definitions across countries (gallons, ounces) creates a patchwork of confusion. There’s no unified logic—units evolved from disparate historical practices, not a coherent design. Metric’s standardized, decimal-based approach (meters, liters, grams) is objectively simpler for calculations, scaling, and global communication. Imperial’s charm is nostalgic, but its complexity is, well, a bit stupid for modern use.
Brilliant! Also worth checking out SNL’s Washington’s Dream video!
Having said that, personally I find it easier to remember what a mile is in metres: 1600m is pretty close and very easy to remember; 1608m is very close (I remember it as adding half the initial 2 digits at the end); and 1609m is the closest. It also makes estimating a 10th of a mile easily as that’s 160m or 161m more precisely.
https://youtu.be/JYqfVE-fykk
Those ai things are useless.
I once asked it how tight a nun’s nasty is and it even refused to answer. It thought it was “inappropriate”
Why do people insist on posting their AI slop? No one cares what From ‘says’.
The arrogance of ignorance?
Units are hard. For example, .002 cent is not the same as .002 dollar…
Metric vs Imperial always stirs up a hornet’s nest, because measurements seem culturally tied.
It’s particularly hard for the US, because in everyday experience it’s still a US customary unit world, so it seems “normal”, but then the rest of the world keeps telling Americans they’re wrong so it’s natural to get defensive.
But the internet makes clashes between Imperial/US Customary and Metric stark, because posts are available everywhere and at least for English speakers, US posts dominate.
I’m a Brit who grew up as the first generation exposed only to metric in schools (i.e. from the early 1970s) and I can’t tell you how depressing it is to still have to fight for its use in the UK in all sorts of contexts.
Nevertheless, a few corrections to the article.
The metre (spelled that way for every country apart from the US) hasn’t been defined in terms of the pole to equator distance for decades. It’s defined as the distance light travels in 1/299792458th of a second.
Secondly, the inch has been defined in terms of the metre since near the beginning of the 20th century. It’s 0.0254m.
Thirdly, UK road signs do give distances in miles, but motorways (freeways) and dual-carriageway (2 lane) ‘A’ roads have small signs all the way along them in metric units at 0.3km to 0.5km intervals. So, technically-speaking you could say most of the road signs for these roads in the UK are in metric! Also, bridge heights are given in metric and imperial (lots of EU trucks travel the UK).
Fourthly, the UK government around 2021 wanted to make metric optional on produce after Brexit, so they ran a consultation. It had pretty loaded questions which made it nearly impossible to say you preferred metric. In the end, about 100,000 people replied 99% of them saying they either preferred having both or preferred metric (18%).
https://metricviews.uk/2023/12/27/government-confirms-metric-measurement-rules-to-stay-as-99-reject-greater-use-of-imperial-units/
😂😂😂😂😂😂😂
And how are you supposed to measure that to prove that 1m of yours is in fact 1m as defined by 1/299792458th of a second? Click a button on a stopwatch? Your hand would have to accelerate so fast that your skin would turn from biology into physics.
You can’t even see a light moving in the first place. This kind of idiocy is what makes ESA a joke it is compared to NASA.
FWIW we’ve managed to build a fleet of Space Shuttles, the ISS, Saturn V, GPS constellation, Voyager probes that have left the Solar System. You only managed to argue and bicker, until 2024 you haven’t even been able to send anything into space since Russia banned ESA from using their Soyuz rockets.
No matter how stupidly meter is defined yard is still defined as 0.9144 of a meter. So even you guys embedded “yard<meter” in yard definition.
These days we have electronics fast enough to measure the time of flight of light directly, and they’re in consumer electronics as well. You could probably whip something up with a pen laser and an oscilloscope/function generator.
It’s a matter of how many digits of precision you demand to call it. The definition simply gives you an exact target.
It has been possible since the 1970’s.
https://en.wikipedia.org/wiki/Femto-photography
Of course you can’t see photons moving, because you have to absorb a photon to see it, but these days even youtubers can afford camera technology that is fast enough to capture and visually slow down the propagation of light to the point that you can see how a pulse of light moves through space. It’s a technique based on sending multiple pulses of light and capturing them at varying time intervals, which means they have traveled different distances, which means you can reconstruct and see the movement of light.
Shine a laser pointer through a toothed wheel on a mirror and spin it so fast the red dot appears on both sides of the teeth. Get the time of flight by the rotational speed, radius and teeth count, and the length by twice the distance from wheel to mirror. Better results when done in vacuum.
(disclaimer: not my idea, this experiment is kind of classical, originally to measure the speed of light)
Oops. You used length measurements twice in the parameters of your length definition machine.
ok, get the time of flight by counting teeth and the rpm
About 50% of the engineers at Houston were British, imported from British Columbia. So, you could say it was Brits who got Amstrong to the Moon :-) . The AGC of course worked in metric except when it displayed feet/s on the DSKY for astronauts.
Ariane 6 is up and going, so we can. Also, ironically, Brits did send a rocket with a payload into orbit in 1971 (stupidly we immediately cancelled the programme after its first successful orbital flight).
https://en.wikipedia.org/wiki/Black_Arrow
The metre (spelled that way for every country apart from the US)
Pretty sure thats not true :) Id almost reccon only the french and brits prefer ro call it that.
Dutch and afaik germens call it ‘meter’ in their language and thus almost always gets the american spelling from those.
Not sure about any others of course, but dont recall having heard/seen it from indians, greeks, chineese or spanish for example. But who knows.
The problem is that insistence that someone is wrong.
Neither are wrong. What system of measurement you use is not important – only that it’s consistent across the usage area.
Metric provides no advantages over Imperial in every day use, Imperial provides no advantages in the exceptional cases (very large or very small) that metric excells at.
Stop arguing.
I like metric because its simple.
Simple as in litres, kilos, speed and weight.
You can have your stupid measurements and bolt dimensions in the US, ill survive.
I propose that we stop calling them “imperial” measurements and instead go with “medieval” measurements.
For example:
1996 was a terrible year for the Ford Mustang because half the fasteners require metric tools, and half the fasteners require medieval tools.
You mean ‘mediaeval’! :-)
That’s a very good answer. Also worth remembering that those medieval measurements came from Charlemagne, so they too are French!
“… the comment section went wild…” and continued/forked here.
Quoting someone from them internets, “They’re all excellent for their own uses. ” The topic on that thread was “which numeric system is better, binary, octal, hexagonal, etc”.
I 100% agree with the point stated above – instead of “imperial” we should go with “medieval”.
It recently came to my attention that spark plug threads have been metric for quite a while.
Regardless of which standard is preferred, the numbers should ALWAYS be accompanied by the symbol of the system used. 1.23cm or 25in or 0402m.
Dont have just numbers on the schematics with a tiny note on page 946 stating “All length dimensions are metric and all torque values are imperial”
Ya, an extra keystroke per number but this alone would have prevented most, if not all of the “Oops, we used the wrong standard and lost lives and/or millions of dollars of equipment” issues.
Jimmy Rees covers it well:
https://youtu.be/GDUt-Kbxqsg?si=LrRCO51ET1Ea18zD
I’m happy I’m old enough to be able to happily switch between metric and UK imperial while building a wooden boat in the UK using plans from the US with measurements down to 1/32 inch while most of the supplies I have access to are metric, though plywood sheets are still 4 x 8, just sold as 1220 x 2440mm.
One of my favorite examples of mixed measurement systems are the typical screws in a PC. The screws for mounting 3.5″/5.25″ hard drives and the like, the power supply, and often for securing the case panels, are #6-32. On the other hand, the screws for the floppy drives (remember those?) and many of the other external facing 3.5″ devices are M3.
I’m a little out of the game these days, but I want to say that 2.5″ SSDs are M3. And I’m pretty sure that the M.2 slot uses an M2.5 screw to secure the card.
Years of PC hacking has left me with a decent store of short #6-32 and M3 screws. Probably enough for the rest of my life.
Even from a safety point of views, some of those threads should be discontinued… M5 screws can fit a 10/32 threaded hole…. Till it falls all apart and squashes someone!!
And fans screws are different as well.
I mean…. The funny thing is that, since president Carter, all imperial units are defined using the ISO standards… So one inch is exactly 25.4 mm, one pound is 0.45359237 kg (they could have rounded that up a bit) and so on ….
My prediction for the future of the US: they will switch to feet only, speedometers will have feet not miles and where they now use inch it will be 12th-of-a-foots.
IF possible they will even do the temperature in feet somehow.
(N.B. This prediction is applicable only if the US continues to exists.)
“…if the US continues to exists…” seeing how things are turning, it is about time the original 13 states north of the Mason-Dixon line join our only northern neighbour and return to the Commonwealth. One move will finally fix many problems in one go, switching to the solid metric system, etc.
Tea Party II, so to speak.
Be careful what you wish for. A Tea Party can quickly degenerate into a Lemonparty.
In New Zealand/Aotearoa we use litres/metre and very rarely see anything else, only things like 2.5inch hard drives and 6 1/4 dropsaw blades from overseas markets. See the Weights and Measures Act 1987 https://www.legislation.govt.nz/act/public/1987/0015/latest/DLM102984.html
What does really annoy me is Shoe sizing, UK, US, EU, kids, its all a complete mess, and UK sizing is based on barleycorns! https://en.wikipedia.org/wiki/Shoe_size
US is using metric system for money (1$ = 100 cents,…). Why they not using British customary system: https://en.wikipedia.org/wiki/List_of_British_banknotes_and_coins ?
rest of the world: “use metric everywhere!!! we don’t use imperial stuff anymore!!”
remind me again what the HP spacing in racks is again? I guess those things were only developed and standardized in America, right?
rest of the word: “well that’s an old standard! you can’t expect us to change all of that!”
why yes. that’s the point.
And once again this discussion devolves into arguments about dividing 12 by 3 and people conflating decimal with metric. The reason that the metric system is superior is that it is a system, design and refined to work as a system. For example, one Joule equals one Newton-metre equal one Watt-second. Because it was designed that way. Units work together with, where-ever possible, a minimum of conversation factors. As an engineer who’s worked across multiple disciplines (and these days what engineer doesn’t) and in both sets of units, you get to see that advantage immediately. This is the decisive argument. Everything else is window dressing, personal preference and habit.
“…but have you ever bought a plywood sheet that’s 1536 x 3072 thirty-seconds? (That’s 4’ x 8’, or 1200 mm x 2400 mm.) No, you haven’t.”
Yes, I have: https://www.bunnings.com.au/ecoply-2400-x-1200-x-12mm-non-structural-plywood-12mm_p0340315
A classmate in the 1970s when metric was months away from adoption in the US was asked how much a kilogram was. “Two pounds,two ounces and a couple of loose joints” was his reply. It’s stuck with me ever since.
I had an engineering professor once who once worked at NIST, who noted that at the highest level, sometimes unsavory units were used, especially units for pressure, which don’t properly belong in either metric or US units.
The moral of the story: Units you don’t like aren’t going away any time soon. Get used to it.
In the UK, newspapers use stones and pounds when quoting people’s weights, but the medical profession actually take and record people’s weights in metric units. The pressmerely convert to imperial because they think that is what the customer wants.
Houses have been built using metric plans since the 1970’s, but estate agents still insist on use imperials units when selling houses.
I could go on, but in short it appears to me that in the UK, thd professionsls use metrics units but the peasants Ute pressured into using imperial units.