Heated discussions come up in the comments section every so often, where American tool users either complain about the glacial pace of adoption, or opine on how inches, pounds, and other such units are just fine.
30 years ago, I was taught as a kid that metric units would be the future standard in the USA. So… when’s that happening?
There are 1,000,000 mm in a km. How many inches in a mile? Um…
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A recipe calls for 3/4 cup of flour. You want to make half a batch. That’s… how many tablespoons? (Why are we still baking with volume anyway, weights are so much better!)
How many ounces are in 3.4 pounds? I need a calculator to tell me 3 lbs 6.4 oz.
Meanwhile, the range in temperature from 68°F to 72°F feels quite different. That’s 20°C to 22.2°C. I prefer the resolution of Fahrenheit.
Scientific fields use international standards, which are predominantly metric. There are some differences, such as with Kelvin being more common for temperature.
But in engineering, imperial units are still popular.
Things get messy when converting things like inches per minute to mm per second.
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What is the nominal size for a letter F drill bit? I know it’s the clearance size for 1/4″, but had to double check the actual size.
Oops, it looks like I was wrong. Apparently, according to Google’s AI Overview, an F drill bit, with 0.257″ diameter, is “commonly used as a clearance hole for a 5/16-18 fastener, allowing the bolt to pass through freely.”
0.257″ is a clearance hole size for 5/16″ fasteners?!
Here’s where inch units get in the way. What’s the decimal for that again? I always seem to remember for 3/8″ and 5/8″, but need a calculator for 5/16″. That’s 0.3125″.
How is a 0.3125″ fastener going to pass through a 0.257″ clearance hole?
My brain is firmly anchored in both worlds – I can’t process inch/SAE/imperial units for certain things (mainly science contexts), but I also can’t think in metric for a lot of engineering and construction-type contexts.
Orange juice isn’t sold in half gallon cartons anymore – Tropicana is down to 46 ounce bottles. How many quarts is that? There are areas where metric units such as liters and milliliters just make sense.
Bottles of water and other beverages are sold in liters (33.8 ounce). But then we have 12 ounce cans and 46 ounce bottles.
It is what it is, we deal with it. It’s like how Phillips head screws and screwdrivers are still around – because change would require impetus.
Money has been spent on getting rid of BPA-containing plastics in many consumer goods, and getting rid of paper straws and plastic bags in many areas around the country. Certain artificial food dyes are being phased out in the USA.
But deliberate efforts to simplify how you buy liter bottles of soda, orange juice in ounces, and dairy products (milk, cream, etc) in quarts? Nah.
Every now and then frustrations poke through in the comments section, because yes metric vs non-metric is messy.
So, here’s your chance to rant about the metric system in the USA – or lack thereof. I guess it’s an opportunity to rant about the state of “AI” too.
Bonus: “The Metric Continuum”
This chart, by Elizabeth Benham at NIST, explores the concept of a “metric continuum.” Their blog post also references the concept that becoming metric is not a one-time event but a process that happens over time.
The USA is moving there, albeit very slowly.
At what point do I want to adapt further? That’s a serious question I ask myself. As I plan out my next project, my inclination is to use imperial units – mainly inches. But is it worth forcing myself to think about things in metric dimensions, such as mm, and should I design from scratch using metric hardware, such as M6 instead of 1/4-20? “Maybe next time.”
EG
Metric is superior for sure, agreed on Fahrenheit, and AI sucks ass
Adabhael
This is the first and also winning comment. No more needs to be said.
A W
Nate Bargatze’s take on this is fantastic though.
https://youtu.be/JYqfVE-fykk?si=BJDousHpu57qSq3R
Avi
Mainly agree, with one caveat for metric, fractional measuring is very handy for when you need to get a bit more accurate.
Wayne R.
I’d say just the opposite.
Stuart
A mm is around 1/25 of an inch, but you can have 0.5 mm increments for around 1/50 inch resolution.
Yes, 1/64 inch offers even more resolution, but 1/64 and 1/128 are not commonplace levels of accuracy.
You can go down to 0.1 mm increments, which is around 0.004″. At that level, ~1/250 inch, fractional measurements are just impractical. 0.2mm is finer than 1/100 inch.
avi
So I went for brevity and ended being misunderstood. Yes metric is more accurate. I meant a bit more accurate, with emphasis on the “a bit”.
I’ve got my tape measure so I’m either rounding to cm or I have to go down to mm, that’s a big jump in units. Where as with fractions if +-1/4″ isn’t cutting it, just break it in half and use 1/8ths. It’s a minor quibble, like pain points in daily life. Kind of like your example with temperature, you could just use 0.1 degree Celsius graduations and then poof, it’s better than Fahrenheit
Jim
I’m a retired power tool product manager, and I made it point to the development engineers to have the size of user-adjusted screws or bolts included in the mold whenever possible, to minimize the chance that a user attempts to drive an imperial screw into a metric-threaded hole or vice versa and thus strip out a hole on a housing or expensive part.
At the risk of stating the obvious, the move to metric fasteners is large the result of Asian manufacturing (all in countries that use metric system) and the desire to make each product able to be sold worldwide and to not create a special version for the USA with imperial characteristics, such as imperial fasteners and measurement markings.
JosephP
I’ve found in prefer C over F for the last decade since a friend told me a useful metric temperature marker points being every 10 degrees.
0C- freezing, winter coat
~10C chilly, fall hoodie or jacket
20C room temperature, comfortable
30C is hot, you’ll want shorts
40C+ is NOPE, 104F+, you’re going to want to be in AC
Stuart Y
Despite my best efforts
I can only remember:
0C is 32F
28C is 82F
and
100C is 212F
Will
Here here!!
John
In doing CAD for my projects, I use standard and metric. Not that big of a deal. Digital calipers make that easy.
On to more pressing matters, AI is successful at only wasting large resources for garbage gain. Where are all the medical breakthroughs, or calculations that solve real financial issues. Oh yeah, nowhere. People are making stupid AI videos, or just too lazy to find real information instead of being spoon fed slop. The entire estimated U.S. GDP increase this year can be attributed to AI spending alone.
KMR
Employees of Google won the Nobel Prize for this:
“One of the Biggest Problems in Biology Has Finally Been Solved”
“Google DeepMind CEO Demis Hassabis explains how its AlphaFold AI program predicted the 3-D structure of every known protein”
https://www.scientificamerican.com/article/one-of-the-biggest-problems-in-biology-has-finally-been-solved/
https://www.nobelprize.org/prizes/chemistry/2024/press-release/
Google staff won another Nobel Prize this year, again for science related breakthroughs that were aided by AI.
Just because you aren’t aware of the advances and break-throughs, doesn’t mean they’re not happening. AI is a tool. Just like any tool, you can learn to use AI, you can ignore it, you can mis-understand it, and you can mis-use it. AI isn’t going away, it is not just wasting large resources. AI’s efficiency of resource use, accuracy and abilities are improving with each new model and major hardware releases. Anyone that just sees the garbage and gimmicks that AI can produce, and wants AI to disappear, is on the wrong side of history.
Stuart Y
AI (machine learning) is just Math!
KMR
Most people know that.
S
I vaguely remember some very confident public statements in the same vein in the drastic push in the 1970’s-90’s for self driving cars.
That anyone not supporting them would be on the wrong side of history.
Of course, the same era also predicted that the Internet would make us all far more intelligent, and we’d all work far less than 8 hours a day.
Not every emerging technology supporter is correct in the long run.
Ron
Until all us old time tradesmen are gone. Including me. We will continue to use imperial or inches. We grew up on it, it was pounded into us. It’s all we’ve ever used. The next generation can deal with Metrics.
Troy H.
Imperial isn’t going away with you. It just doesn’t need to. SI/Metric is a good system and much better suited to a scientific and engineering environment, but the reality is that the imperial system is plenty sufficient and generally fit for purpose.
The metric system was conceived to be a universal system that covers everything. The imperial system is an agglomeration of measurements that were created for particular applications and because of that, they still work well in those applications. They’re troublesome to convert between, but the reality is that they persist because you frequently don’t have to convert between them.
An acre is 1/640 of a square mile or an area 1 chain by 10 chains (66ft x 660ft) and it was conceived to be approximately what a man with a team of oxen could plow in a day. Many land parcels were platted using those units all across the world and converting those measurements just doesn’t really provide that much additional value. Measurements used in farming and surveying and irrigation make intuitive sense for that application even if they sound unintuitive,… and more so than their metric equivalents. In a world where things are measured and calculated digitally it makes good sense to use a universal system of units, but when things are being measured and calculated manually, these customary systems make good sense. An acre-foot seems like a ridiculous measurement for the volume of a body of water until you think about irrigation planning.
I just don’t like the idea that goes around that imperial measurements were created by stupid backwards people. They weren’t. They were created by people who were trying to accomplish tasks rather than by people who were specifically trying to conceive of a universal system of units of measure and the reason customary measurements persist is that they’re still useful and intuitive within the applications where they were created. Fahrenheit degrees are a great example. 32F and 212F as the freezing and boiling point of water and instead dividing that difference into 100 degrees makes sense for scientific analysis, but Fahrenheit provides more resolution and more useful indications of temperature in the realm of weather and human comfort.
How many inches in a mile? I couldn’t tell you off hand, but I can tell you how many times in the last 10 years I’ve needed to know how many inches are in a mile… because the answer is zero. Would it work out fine if everyone in the world fully converted to the metric system? Sure. Is the juice worth the squeeze? Definitely not.
Stuart
I prefer F over C, but could probably cope if I had to set the thermostat to 21.5°C. Too cold? A 0.5°C jump to 22°C is similar to a 0.9° F rise in temp.
Really, I just want to simplify my tools and how I approach project dimensioning, but I’m firmly anchored in imperial sizes and units.
Cando
I’m in Canada, where we use Celsius, and I’ve never in my life seen a room thermostat that lets you set half a degree, nor have I ever thought that that would’ve been useful. Maybe I just don’t know what I’m missing.
Vards Uzvards
My home thermostat (in the great state of New Mexico) is set to 23.5 degrees Celsius.
Alex
I’m in Canada as well and all my thermostat have 0.5C degree increments (including my two heat pumps). It’s pretty common.
Jack D
I think you’ve said it best, right here.
John
As a construction PM, 99.999% of my work is imperial. Sure equipment cut sheets have metric equivalent measurements next to the imperial units but they are all but ignored.
The .001% of my work that is metric was 5 years ago. It was a Federal office building in Washington DC designed in the 20s, completed in the 30s using the imperial system. The renovation we were part of was all designed in metric. No one knows why but we all questioned it. We bought metric tape measures for everyone but all of the trades started using conversion calculators on their phones to go from mm to feet and inches.
Stuart Y
Metric is easier and convenient, but similar to learning a second language, we “think” and understand in our first/native language.
Until a generation “thinks” and doesn’t have to convert, this dilemma will remain.
I’m an engineer and metric is great for solving problems and simple units, like in college, but I understand pounds more than I think kg’s. Thus the difference in getting the answer and understanding that the answer makes sense. Weight here is a simple example: for fun think pressure psi vs MPascals
Jason Watkins
I work for a car manufacturing plant. We deal entirely in MM. Most things have a tolerance of less then 3MM. 5MM is the highest tolerance I’ve ever seen. trying to use “American” measurements wouldn’t work at all.
TomD
Thousands of an inch work fine, and better than MM. mils.
Best/worst of both worlds!
Stuart
Why would mils be better than mm? Don’t like mm in decimals? Switch to µm.
Matt_T
The pro metric crowd push the slightly easier math benefit hard whilst ignoring the considerable real world costs of switching. And it’s really debatable whether the math advantage still matters in the computer age when the kids who’ll be taught metric aren’t taught math anymore.
jec6613
Working in a Base10 system is more difficult math-wise for a lot of work than a Base12 system. Need to divide into quarters or thirds?
The other part of the old system that’s not going away is the yard, because 2,000 of those is one minute of latitude, which is one nautical mile.
MotoJ
”The other part of the old system that’s not going away is the yard, because 2,000 of those is one minute of latitude, which is one nautical mile.”
One nautical mile was intended to be 1 arc minute of the equatorial circumference of earth, so the circumference would be exactly 21600 nm. The measurement wasn’t exact and has evolved as measurement technologies have advanced.
Today there are 6076 and some fraction of foot in a nautical mile, or a tad over 2025 yards in one nautical mile.
Tony
Why is it such a bad thing to have both?
I think it’s more of a financial issue as to how much money it would cost for us to make the change — including making changes to software, signage, rewriting legal standards, etc. Who is going to pay the enormous price tag?
Avi
Even putting money aside, people tend to develop a feel for approximating measurements with the units they use, similar to immigrants and languages. Not sure all those raised in imperial are willing to emigrate to metric living, however after a generation or 2, everyone should be fine
Troy H.
And how much value does the conversion actually bring?
As time goes on it is less and less. Computers are doing the major important conversions at this point so the labor cost is negligible. Would a consistent system technically be better? Perhaps. However, there isn’t actually a huge amount of economic value in ideological optimization.
Tony
Well said.
Matt O
For woodworking (where you aren’t measuring to the thousandth), I find imperial math to be far simpler.
Half of 3/32 is 3/64. You just keep doubling the denominator. 1- > 1/2 -> 1/4 -> 1/8 -> 1/16, etc. Get the denomators straight and you can add them.
You want to find the center of a board that is 51 and 7/8? 20 and 1/2 + 7/16 = 21 1/16.
For me, that is easier in my head than 51.875/2 =25.938
Wayne R.
Someone a long time ago told me that, “kilometers and megahertz were pretty much the same.” And we were in roles where that was pretty important.
And for conversions, just look at Amazon with lots of vendors trying to sell the same thing, the sizes, weights, counts and “cost per” units vary wildly to the point of near uselessness.
I generally prefer metric, but temps are difficult – especially mental conversions in between the two zeros (for me, anyway).
I’m sure we still have Imperial/customary/SAE/silly mishmash because most people just dislike thinking.
Matt
Lol, and I did the imperial wrong in my head, I should type slower.
51 and 7/8 divided by 2 is 25 1/2 + 7/16 = 25 15/16 (=0.938)
Bonnie
There is not enough time in the world for me to care that much about what system I’m using if it works. I use both as befits the task at hand.
It’s really not that big a deal.
Kevin R Franklin
I have worked with both imperial and metric for the past 50 years, and I find metric to be much easier than imperial. This is in machining and collision repair. When checking the specs on a vehicles structure (panel alignment and chassis and frame) it is much easier to use. Measuring in thousandths with machine work, I find it to be a very similar thought process. The only thing I regularly use the imperial system for, is carpentry.
MikeK
“Why are we still baking with volume anyway, weights are so much better!” Because not every home has a food scale, just like not every kitchen has a meat thermometer, Fahrenheit or Celsius.
Every time my friends from metric-using countries complain about us, I remind them that you can still see road signs in the UK and Ireland showing distances in miles and feet. They still sell butter in pounds, eggs in dozens. As for the US slowly converting liquids to metric, note that they’re doing that partly to cheat us. You used to be able to buy a quart of whisky; now it’s 750ml, which is LESS than a quart. Did they lower the price? Of course not.
I’m a proponent of metric for actual measuring. As a photographer who used to process his own film, it was pretty easy to see on the Kodak F and C thermometer that the typical range of processing BW film (68F to 75F, which is 20-24C) is also what we Americans think of as the “comfort zone” on our thermostats. A meter is 3″ longer than a yard, and most of us can visually tell how far away that is. For 95% of American uses, close is good enough. For those who need to really measure, we have the tools to do so. Pretty much everything on a car is metric now, thanks to globalization. That’s what needs to happen to everything else.
We watch British home building and renovation shows, and it’s amusing how the builder will say “It’s two mils out.” By eyeball!
Troy H.
I don’t think the argument that everyone doesn’t have scales makes much sense when the alternative requires a different tool (measuring cups and spoons) but the rest of it is reasonable.
For some types of cooking, like baking, measuring by weight is technically superior but volumetric measuring is obviously sufficient. Aside from baking, to a large extent you don’t need to measure things at all while cooking.
Dozens are a fun thing to fight about. Base 12 is useful because it is evenly divisible by 2, 3, 4 and 6 whereas 10 is only evenly divisible by 2 and 5. On a similar note, power of 2 divisions are easier to create geometrically than power of 10.
To some extent, I know a bunch of this stuff because I like to having low stakes arguments about subjects and metric vs. customary gets a surprising number of people exasperated.
MM
Agreed. That argument did make sense in the past: A few decades ago a kitchen scale was expensive while anybody could afford a measuring cup. But that’s not really true anymore. These days there are loads of inexpensive electronic scales out there.
It’s the same thing with thermometers. In the past they were an oddity, these days instant-read electronic thermometers are readily available and inexpensive. The remote-reading type you can leave stuck in something while it’s in the oven or grill/smoker are also fantastic. Thanks to them there is zero guesswork as to when the meat is done.
MikeK
Just because something is available to buy cheaply doesn’t mean that someone that has been cooking successfully for 30 years is going to feel it’s necessary to buy one.
MM
A person who has 30 years of successful baking experience probably doesn’t need a measuring tool of any kind and can do it simply by taste and feel.
A person who doesn’t have the experience would be doing themselves a serious disservice by eschewing a scale or thermometer.
avi
The difference is that my measuring cups never just decide to stop working (except that one time when shattered into a million pieces on the kitchen floor) cheap scales however…
Nevermind the assortment of small button batteries I need to keep in stock
notinuse
From what I remember, a 750 ml bottle replaced the fifth, not a quart.
MT_Noob
I’m mostly o.k. with switching, although I would personally struggle with mentally visualizing kilometers instead of miles. And I would never want to give up the Fahrenheit scale.
While we are at it, lets switch over to A4 paper and get rid of the fiddly paper tray adjusters for switching from 8.5×11 to A4 in printers and copiers. They are always going out of adjustment.
Otherwise, like I said I am pretty much o.k. with most changes, but in my mind, Fahrenheit and Pluto forever.
MikeK
Take up running and you’ll pretty quickly understand miles vs kilometers. I agree about paper, my printers have so many paper sizes that I’ll never use. I’m always printing an 8×10 photo on 8.5×11. (See, it’s even hard to type the 1/2 inch without going decimal)
Pluto Forever!
MT_Noob
If I cast my mind back to prehistoric days, I seem to recall running the 880 yard in school. If I recall correctly, that was a half mile and was my limit for imagining distances (and my endurance for running). Hats off to anyone that can run farther than that.
Maybe I should make a new years resolution to get back into shape and start running (in either miles or kilometers).
Of course, I would need to get some running shoes. Not sure if I take a size 9 1/2 or 45. (Yet another measurement system.)
Pluto Lives!
ElectroAtletico
The US government claimed in 1976 that by 1980 the US would be fully into the Metric system. 45 year later we’re still dealing with that Imperial bullshit. 3D is a hobby of mine and it that community is 100% metric. Time to knock off this crap and finally move fully.
TonyT
Imperial is never going away, but it might be stated in metric. In other words, a 1/4″ bit is a 1/4″ bit, whether you call it that or 6.35mm
I use a mix of systems, but for engineering I do use metric and try to use metric hardware when available.
Btw, metric paper sizes are very hard to find in the US. I’ve only found them in person at Kinokuniya and Daiso. Putting aside Japanese paper sizes, the metric series were designed to have the same aspect ratio, e.g. for A2, A3, A4, A5, A6. There’s also a B series, and maybe more.
Stuart
Metric paper and notebooks are readily available online. You can often metric-sized journals and similar at art supply stores or maybe specialty and stationery stores.
TonyT
Last time I looked, only Hammermill made A4 copy paper in the US, maybe there’s a lot available from China now, that was over a decade ago.
The majority of my notebooks are A or B series (thanks, Daiso plus online) but again, most online stationery stores don’t sell affordable A4 printer paper.
Vards Uzvards
If you ever use paper sleeves (plastic sleeves for paper), very soon you’ll realize how impractical it is to use A4 paper in the US.
TonyT
You just a neighborhood Daiso next door, they have a lot of A and B series products, including sleeves.
Vards Uzvards
Our nearest (it’s not in our “neighborhood” – need to drive to Albuquerque) Daiso opened its doors this year, and it’s probably only the second such store in New Mexico.
John Fleisher
We need to focus on the important issues, like why are hot dogs sold in packs of 10, while the buns are sold in packs of 8?
What am I supposed to do with those two extra hot dogs? Let them “accidentally” fall off the grill so the dog can eat them?
John
It’s a conspiracy perpetrated by Big Canine!
Robert
We were trained in engineering to comfortably go back and forth between Imperial and metric. I’d prefer to switch over wholesale to metric. But in the USA there’s a lot of social inertial not to from the salt of the earth folks.
fred
I’m an engineer by education, a university that saw fit to grant me a degree, and a few states that gave me PE licenses. But I probably used my MBA more as I took over and bought relatives out of a family plumbing business then got involved in buoying into a few other rather loosely related businesses. I was educated in PSI, BTUs, degrees Rankine and so on – but converting back and forth to metric was never a big deal – even though slide rules (not calculators) dominated my college years.
What I found interesting over the years is not so much to do with metric versus Imperial – but all the oddball implementations of both that either arrived or disappeared in the manufacture – then maintenance of things. Many years ago, I was interested in British motorcycles only to find that Whitworth standard was different. Then working on bicycles proved another challenge sometime requiring oddball taps and dies. I soon learned about different inch-sized thread forms and screw pitches like BSB, BSC, BSW AND BSPT that were different from UNC, UNF, UNEF.
In the plumbing business while NPT threads were commonly – we’d see assemblies with NPS or even BSPT. When i got into the fabrication business and we were refurbishing older aircraft assemblies – all bets seemed to be off with threaded parts/holes that conformed to none of the usual Imperial or metric standards that could only be serviced by taps from suppliers like Pratt and Whitney or other aerospace companies. I thought that metric surely took care of all this confusion – but I learned that ISO, DIN, BNAE, JIS and other standards sometimes differed – and also learned to say Löwenherz when thinking about threads on parts of old precision instruments. We were blessed by having a machinist who took care of our tool room – who was savvy about all of this – but even he was stumped from time to time.
zchris87v
Yep, mechanical engineer here as well. I’ve worked for two international companies as well as one American for a short time, so my mind predominantly works in metric. When you’re making parts with micron tolerances, thousandth of an inch doesn’t work. I currently do a good bit of work with retired guys on house repair, and they get fussy that I can’t easily pick out the 11/16″ mark on a tape measure quickly. But if I knew it was 17.5mm off the top of my head, I could probably guess the mark without a scale and be within 1-2mm. When I measure with calipers, I always use mm and just convert.
Kurt
Since I got into 3d printing I have been getting more metric measurement tools and fasteners. I use whatever appropriate for the project I’m working on – fractions for woodworking, decimal for machining, and millimeters for 3d. It’s not that hard to switch between.
I still prefer freedom units for temperature LOL
MM
Personally I find the whole Imperial vs. Metric argument a bit silly. They are both arbitrary systems of measurement and they both have pros and cons. It is also easy enough to convert between the two of them: 25.4mm to the inch, 454 grams to the pound, and so on.
Depending on what I’m doing I think in terms of inches, mm, “thou”sandths of an inch, or 64ths (1/64 inch). I handload and shoot antique guns so I’m also used to thinking of mass in units of grains and drams. I use Japanese woodworking tools and have a general interest in Japanese blades so I’ve come to learn the old Japanese length measurements of Shaku, Sun, and Bu. I have always thought about pressure in terms of psi; lately I’ve been learning about spray painting from a Brit who uses Bar when discussing air pressure…at first I was doing mental math to convert, now I just “get” it without thinking about a conversion.
I don’t think any one of those systems is better than another, they’re simply different. They’re just numbers in the end.
Jared
I’m in Canada. While we’re officially metric, there’s still many things where imperial is commonplace. E.g. our dimensional lumber products, a “litre” of engine oil is often actually 946ml to correspond with a quart, etc.
While my navigation program gives me directions in kilometers, and that’s what I most readily understand while driving, I wish it would tell me how many feet until the next turn (how far is 300 meters? I can’t visualize that until I start thinking of it as roughly 1/3 a kilometer).
I agree with your sentiment – it’s strange how much of the utility is just what you’re used to.
S
I absolutely agree. As long as all parties know the measurement system in place, it doesn’t matter what standard it is.
In my youth, much of my hardware learning involved fixing bikes, so much of my childhood was mostly metric fasteners.
I honestly never ‘got’ fractional measurements until about 25 years later. The imperial decimal or metric is just much easier for me.
Most of my personal projects are in metric, while my paid-job projects are in imperial.
NotThisMark
Feet/Inches/Yards is great because it is base 12. Base 12 is great at many more fractions than base 10, especially when you do 1/3. The same reason time and degrees of a circle are done in the fashion they are. It is a huge advantage when doing calculations in your head. It breaks down when you get to miles and acres but neither system is perfect.
Some things are great about metric, but why does it seem like metric bolts are always fine thread? Fine thread is great for some things but really sucks for many applications.
Chris T
I’ve decided that I prefer the metric system in two aspects of my life.
The first is in navigation. Whether it’s on the road when running. Or, in the woods when hiking. I can do metric math in my head without stopping as meters and kilometers are easy to mix and match.
The second instance is building wire antennas for radios. How much material do I need for the two meter band? Easy peasy.
Ben
I prefer oil field units, such as Gbbl, or Giga-Blue Barrels.
JoeM
Now, Stuart… You don’t want ME Ranting on this subject!
I will a tiny bit though. Literally tiny. I find there’s a threshold for where the Metric System and the Imperial/SAE System have a firm grapple hold on their size dominance. It’s down to precision. Literally. Millimeters are easier to measure very tiny things, such as drill bit diameters, nails, screws, and threads on fasteners. Centimeters work extremely well for medium-sized objects, such as cups, flasks, tiles, boxes, anything you can hold in your hands. But there’s a threshold. The Human Body itself. Pounds for weight, Feet/Inches for Height, is easier to understand about people, but only people. Once it’s back to an object, Metric Kilograms and Grams return to being more accurate. The decimal points are better than fractions. You just slide the decimal point to where you need the unit. Whereas Imperial/SAE doesn’t always follow the same resolution of units for those fractions. Some Tape Measures and Calipers count by 64ths, or even 128ths in some cases. Grabbing a random measuring device doesn’t guarantee you’ll always get the same markings to count by. But in Metric, it’s always the same. The smallest they can print, without the use of a digital device attached to compensate, is 1mm. True, a digital element can take the guesswork out of both systems, but when you don’t have the digital assistance, you have to know what you’re looking at. This is easy with Metric, but varies widely for Imperial/SAE.
Imperial/SAE requires you know how big a unit is meant to be already. You can learn the different markings until you turn purple, but if you just run your finger along and point at a specific line on a tape/ruler/etc. to a specific spot, you need to already know how big a foot, inch, and fractions are supposed to be, in order to know what that line indicates. Is it the 32nds, or the 64ths? Is it above, or below the 1″ or 1′ marker? How many times do you need to divide this number up to get the number of whole units, and the number of fractional units, and under what denominator is it listed?
Now, think Metric. You pull out the same measuring devices in Metric. You point to a line. Any line. The smallest it can get is 1mm. A whole number. Are you above or below the standard unit? It’s a decimal of that unit, with its own regular set of tens. So, something could be a whole Meter, or a piece of a meter, and it’ll still be a whole number. At worst, with a decimal. Sliding that decimal is the same as changing units. There is no math, it’s pure measurement. Which is faster, and more standardized.
Oh, and, the AI overview you used at the beginning of the Article is wrong. The clearance hole versus the drilled hole for the fastener to be tapped, are swapped. The 0.257″ is the size of the fastener itself. That doesn’t include how much clearance the actual drill bit causes the hole diameter to be, which is what you calculated at 0.312″ drilled. What is drilled is the clearance for the hole, that’s the clearance diameter. 3.25mm is the size of a standard headphone jack, in metric. That is measuring the actual connector, not the clearance hole, which has a near-zero, if only a few Micrometers’ worth of clearance for allowing the jack to take the connector easily. Converting 3.25mm for a connector does not equate to the drill bit size for constructing things, it’s just a standard use for 3.25mm as the 1/8″ headphone jack. This is where AI isn’t useful, because the more common use is the conversion between audio jacks at 1/8″ and 1/4″, representing 3.25mm and 6.5mm respectively. Since that is mentioned more often in social media conversations, where “AI” farms all of its answers from, it spits out the numbers for connectors as the standard, not the known construction values needed for fasteners. Artificial Idiocy is what it really is. It isn’t any good to anyone, since it’s farming Human Responses without context or understanding. That’s the discrepancy in your article. You grabbed an AI response from Google Gemini. That isn’t Google Search anymore. You’re using their AI, and it got it wrong.
Stuart
When you search on Google, it gives you AI Overviews. I know that they’re giving wrong information, which was the point of sharing it.
JoeM
Yes. But, you did say Rant here! I’m only playing along. That was my AI Rant section of the Metric/Imperial breakdown. If there were smileys or emojis, they’d be more obvious where I’d just be putting them to have a laugh with everyone here.
And you had to know I wasn’t taking it 100% seriously by my opening line! (This would be where the 😀 Smiley would make sense of things. Otherwise it looks like I’m lecturing, when… No, I’m just playing along.)
Stuart
I intended for it to be rant HERE, because the topic came up a couple of times over the past few months.
Greg T
Oh boy santa came early !!! What a great gift ! 🙂
EBT
For Fahrenheit, I just multiply Celsius by 1.8 and add 32. (0 C x1.8+32 = 32F) or what Google says! LOL…
Nice Mitutoyo calipers with both scales!
Digital calipers that allow both from http://www.igaging.com/ip67-digidiall-electronic-calipers.html
(not cheap but then better than two calipers!)
I had an issue with 14mm sparkplug. I needed a socket that could hold the plug. None of my “sparkplug” sockets could work (larger than that). So I bought one for $9 that also had a swivel. So nice. And figures, next time is another 70K miles away (about 7-8 years)
Steven B
My biggest complaint is tool sets. Nearly all nice tool sets have metrics and SAE versions of wrenches, hex wrenches, and sockets. I don’t need those. It’s extra cost, but more importantly, extra weight and bulk.
There are many scenarios where I need a well organized toolkit for specialized scenarios. There are many sets in the price range I want, but they’re always SAE and metric….and for me, space is a premium. For example, a tool kit in my car or my bike bag. I get by with throwing what I need in a bag, but it’s sloppy. I prefer dedicated took organizer so I can see if a socket is missing before I leave as well as keep things tidy.
Vards Uzvards
Can’t you buy a metric-only or SAE-only set, depending on your need?
me
Metric sets like to skip 12,16 and or 18mm. When you need one, you need it.
Vards Uzvards
Buy from Tekton, maybe?
BobH
I think there are some places where imperial is better than metric, and vice versa. Examples:
Feet divided in to 12 inches allows it to be divided by half, quarter, and thirds. A third of a meter is 333.33333333333333333…. mm’s.
Meters and Kilo Meters is a lot better than Feet, Yards, and Miles. Though, don’t forget Nautical Miles for planes and ships isn’t going away as it maps to the degrees of latitude.
For weight, I think metric is better. Not sure why 16 oz. to a pound is useful. Then there are the different definitions of tons (including metric tons).
Metric different length systems of meters, decimeters, centimeters, and millimeters is just complicated. For woodworking in metric I just use meters and millimeters.
Decimal version of each are probably about the same, just based on different things (e.g. meters or miles/feet).
For temperature, I think Fahrenheit works better for people. 0° and 100° are the danger points in Fahrenheit. Celsius 0° isn’t useful and 100° is too high. In Celsius the comfort range for people is too narrow spread over about 10°, vs. Fahrenheit over about 30°.
Vards Uzvards
“0° and 100° are the danger points in Fahrenheit. Celsius 0° isn’t useful and 100° is too high.”
At 0°C water is freezing, and at at 100°C it’s boiling. Aren’t these “the danger points”, for some applications at least? It’s much easier to comprehend that everything under 0°C (i.e. negative) is freezing cold.
For length measurement I can easily register either “20 mm”, or “3/4 and 1/32 of an inch” just by glancing at my ruler. Which is easier, huh?
Brian
And of course there was the $125M spacecraft lost due to using both systems: https://www.latimes.com/archives/la-xpm-1999-oct-01-mn-17288-story.html
me
They should’ve required sae fasteners for any vehicle sold here. At one time, sae bolts were like $3 a pound. Metric? $3 apiece.
J. Newell
Needed to mix up some chainsaw fuel this weekend. Let’s see…
One can was 110 oz. The other was 128 oz. Both were pre-mixed at 50:1, but I run 40:1, how much oil do I need to add…?
I converted both to ML, divided by 50, then divided the original amounts by 40, and subtracted one amount from the other, and got out my METRIC measuring glassware and finished the task.
If I had done it in ounces, I would have been trying to measure difficult amounts in decimal ounces and who knows how difficult it would have been to try to measure it out in fractional ounces.
And yeah, I admit I’m picky about how the fuel is mixed. I want 40:1, not 33:1 or 46:1.
Joel Rappoport
Worked as a roll-grinder, ground 30,000 pound steel rolls used to make aluminum foil. Most rolls were 38” OD, and we ground to a tolerance of 0.0015”. We had four grinders, three were metric made in Germany, and one old Cincinnati, which was SAE. After every few changeovers, which involved breaking the grinder down and rebuilding the shoes we were having to remachine most threads and use inserts due to stripped threads on the SAE grinder. Finally found out the operator thought ‘metric’ and ‘SAE’ were like Ford and GM, brand names. So, he would just grab bolts from the metric cabinet and force them into the SAE threads.
I’ve grown to use SAE for woodworking and structural jobs, and metric for automotive and machine-work. It’s just worked out well over 50 years or so.
Nathan
Lol so someone finally mentioned it what about all the disastrous times a company or org used both units only to destroy something or worse accidentally kill people. We tend to forget about them
And sorry I take some umbrage to engineering in I perial units. Maybe construction is but auto industry worldwide is metric. Sorry those lug nuts on your f150 are not 13/16 they are 21mm. Everything your putting a 5/8 wrench on is most likely 15mm or worse 14mm. Etc etc
As far as I know untill the 787 all Boeing stuff was done in sae units. I don’t know of they swapped but Airbus products are designed in m. And most drawings are in m or cm.
All electric items are metric. Volt ohm etc.
Hell when did you last use degree minute second?
Nautical miles well there are some airlines worldwide that use km and kg weights
Also when was the last time you got actual 3/4 ply. No it’s .708 or such or get this. 18mm
Walter Bordett
The US has been converting to the metric system since Thomas Jefferson. We are still not there. I am functional in both systems. I hope we get totally converted in the next generation, but I’m not highly optimistic.
Kingsley
Here in the UK I went to school in the 1980s and imperial measurements weren’t even taught at school, just metric.
However all roadsigns are still in yards and miles and lots of things in industry used imperial.
Timber is still referred to in inches.
Day to day metric is easier to work with and has basic precision. That said, 25ish mm is one inch and inches and feet are useful.
Every single tape measure sold in the UK has both imperial and metric on it.
I find it strange in the USA to just have imperial.
Ben B
Converting to metric only would not just be theoretical. There is an incalculable amount of hardware (mills with imperial lead screws, grocery scales with imperial units, dies set to cut imperial screws or pipes, and on and on) that would need to be scrapped for it to be a “true” conversion. I think our current system, where technical people have the habit of paying attention to and converting units, and are able to pick the right system for the application, is the ideal system compared to a top down dictation of one system
Alex Peel
Fahrenheit is much better for weather and how you feel then Celsius because it was designed to measure this range unlike Celsius. 100 is really hot for the weather and 0 is really cold. This just makes sense and is really rational. I dont get why people raised on Celsius get confused about Fahrenheit. Even if you cant do the math from one to the other in your head you dont need to. All you need to know is 100 very hot 0 very cold and you can figure everything else out with no math. Much easier than going the other way. Who cares if 212 is boiling when all you are referring to is the weather? Plus its about twice the resolution of metric for this range. Science and other endeavors where the freeze point and boiling point are important Celsius is better for. We might as well use Celsius for everything other than weather (even if I dont), 3d printing is slowly bringing me around on this. Of course the argument could be made following this is why have two measurement systems.
Alex Peel
I find my self using imperial for woodworking as most of my tools are set for this, and this is the standard for hobby woodworking in US. I use decimal inches mainly for lathe and milling, again most of my tools are set for this and this is standard in US (although the DRO makes it easy to switch). I use metric for 3D printing (including the hardware) because this is the standard for 3D printing which is more of a global aligned activity. The exception is if I am making a part that is for something or to replace something thats imperial based. Even then though I usually mix metric and imperial in the modeling which is no problem because even if I accidentally use the incorrect unit its very easy to fix in a cad program.
processwrench
Having worked in both systems for 40 some odd years now, i have a strange dichotomy. For everyday things, inches and pounds, but as soon as things get complicated i go metric. Certainly for mechanical things metric is much easier, way too many easy rules of thumb to pass up, tap size for M8 bolt? subtract 1 gives you 7mm drill (which works most times!). what size wrench for m6 socket head? subtract 2, use 4mm allen wrench. When baking or cooking, trying to figure out half/third/double batches trying to figure out tbsp to cups etc I long for metric! I dispute the whole its easy to switch argument. When designing in either system, people don’t tend to do things like space hole 2.3457298392 units apart, they tend to do 2.5 or 2. Most drawing have a tolerance block, if you tolerance block is based on significant digits X.XXX = +/- 0.005″ for example, so depending on how you rounded up or down now sets the tolerance. Which now goes into the tolerance stack for the assembly. Now you send your part out to a shop to make the part, they come back with an issue making the part, all the work they did is in a different system so they want to adjust things, now you have to convert those numbers back into whatever you designed it to see how it affects the stack, often this bumps the precision up a level just because rounding errors. This is just about always the design in metric and the supplier in imperial. I hate to say this but those that insist on talking in imperial, generally don’t work out as a supplier. Also considering that the decision makers both on the Design side and supplier side are largely international based, that also tends to favor metric
Justin T
For all the bluster about math, I just want 1 set of sizes for fasteners. I’m annoyed that I have a metric and SAE set of sockets, wrenches and allen keys. In these situations, it really doesn’t make sense to keep a second system around. Bolts don’t grow and shrink and you’re usually only cutting them to length because of interference – no need for an exact measure. Just this one change saves me more headaches than how easy or hard fractions and decimals are.
David
You need to be fair. Show a fractional inch dial caliper side by size. The cheap one from harbor freight.
If you live in an inch world, live in an inch world. I’de rather not but here we are.
Stuart
What’s not fair about inch/metric calipers?