Is the whole world metric?

Spark plugs have been metric for a long time .

And, as dadoctah pointed out, tires are schitzophrenic!

I disagree with every comment that the U.S.A. is behind the rest of the world because we still use English units of measurements on most things. The English system is as American as you can get, and the units of measurement make perfect sense. Quite frankly, I find it to be a royal pain in the a## when I’m trying to work on something that ought to have the nuts and bolts in SAE sizes, only to find that I have to dig up a metric wrench (or else I use an adjustable crescent wrench). This country of ours IS the United States of America, last time I checked, so I say let’s keep English SAE measurements for everything when it comes to our own products.

Mountainbike, Here Here! A pint of lager raised to you.

ClassicFan made a good point too. We’re the largest economy in the world. Until recently, we were the largest manufacturing society in the world. Who’s the leader here? We are! There’s absolutely no logical reason why we should change to metric across the board.

But I’d be happy to join you in a pint.

My little rant actually poses an interesting question. You mechanics out there. When is the last time you used a fractional wrench? Does any car made today require the use of such tools?

Trouble is, a large part of the repair business is on cars made yesterday.

When was the last time you did any carpentry in meters?
Shipped anything in kilograms lately?
How tall are your kids?
How much do you weigh?
How big is your house “lot”? Looked at the plot plan lately? What units is it in?
What does a litre of milk go for at the grocery store?
How many kilometers is it to the shopping mall?
Do your roadsign in your town say “Concord 16.09km” or “Concord 10 miles”?
Does your pancake box say “preheat oven to 400F” or “preheat oven to 246C”?
I challenge you, nay, I defy you to buy lumber…or sheetrock…or fencing… in metric measurements.

And, more importantly, does it really matter?

The United States has tried adopting the metric system since 1875. In 1975, Congress passed the Metric Conversion Act of 1975 in hopes of metric conversion but the idea died out in the Reagan years. I don’t think we ever needed or wanted the metric system in the first place. I’m happy just to carry a metric and a standard set in my toolbox. It gives me “more tools” which I like. Besides, I can use a metric socket on a stripped standard bolt and vise versa.

ClassicFan has a point. Converting all industries overnight would be prohibitively expensive. The car industry did it gradually, as new models were designed, they went metric. However engine designs last a long time, so my 1988 Chevy Caprice had a mix of dimensions. New US car models are all metric now. The SAE Journal gives verything in metric, except horsepower and torque; Americans will take a long time to get used to Kilowatts as a power unit.

Industries should change over gradually. Canada went metric in 1978, and today carpet is still sold in square feet along with metric measures, and meat is still quoted in $/lb along with $/kilo. New mothers are given the weight of their babies in pounds, but the medical records are in kilos. The pharmaceutical industry is completely metric as well. Clothing is still sold in English units, as are shoe sizes.

Regardless of what country has the largest economy in the world, about 80% of world trade is now conducted in the metric system, that’s what really counts. China will soon be the largest economy, while the European economy in total already exceeds the US’s, and adding China and India makes the difference even larger.

Will I need to replace my torque wrenches?

Seriously Doc, and you know I have only respect for you, I can’t see any reason to or benefit from arbitrarily converting things to metric. As you mentioned, the auto industry has done so as it globalized. Other industries will also do so as it becomes appropriate for them. Industries for whom it’s not appropriate won’t. The Metric Conversion Act did nothing because the natural forces of the marketplace are far too powerful. Those same natural forces will cause a change where and when it becomes appropriate.

Kilowatts? My electric bill is already in kilowatts.

“The lumber industry even calls a 1-1/2"x3-1/2” board a “2x4”.

There is a good reason for that. The “1-1/2"x3-1/2” board" Started it’s life as a 2X4 and it shrinks as it dries to the 1-1/2"x3-1/2" size

“The lumber industry even calls a 1-1/2"x3-1/2” board a “2x4”.
Rough Sawn Dimensions vs. Planed Dimensions.

Out here in the sticks one can buy rough sawn 2x4s that really are 2" by 4" ! They’re great for some applications.


I agree that forced conversion on a large scale is neither cost-effective or convenient. The industry I work in, energy, is gradually converting to metric, although oil is measured in barrels in North America and in tonnes elswhere. The world price of oil will be quoted in $/barrel for a long time to come, as will the price of gold, silver and other precious metals quoted in $/ounce. Natural gas is now more and more quoted in $/gigijoule, which is nearly equal to 1000 cubic feet. The reason is the value is in heat content rather than volume.

The electrical industry, as you point out has always been international and metric.

The construction industry will be one of the last to convert, since most of its work is national, and much work is to existing buildings.

The clothing industry could very easily convert, but sizes are very personal; when I buy shoes made in Asia, the English, American and metric size are all shown on the label. Shopping for lingerie in Paris, I discovered my wife wears a size 88 bra!

Even the Brits, who converted in the serventies, still use the English measures for distances, and house-based measures. And they still weigh people in “STONES”!

In short, any industry doing a substantial part of its business internationally, will need to convert. US pipeline construction companies, for instance, easily work in both sytems. In my consulting I have to work in both systems on an ongoing basis.

You really don’t need two complete sets of wrenches. 11, 13, 14, and 19 mm wrenches are so close to 7/16, 1/2, 9/16, and 3/4 inch wrenches that they are practically interchangable.

I’ll admit to using both when talking about distance. When talking about one town tot he next, I use miles. But when talking about very short distances, I’ll use centimeters to describe how short it is.

I have a few Ausie friends and they sometimes bring this topic up; why doesn’t the US convert to metric. I jokingly tell them our system is superior and that we’ll invade their country next and make THEM convert to OUR system.

There’s nothing wrong with SAE sizes. The problem is when they’re mixed up on the same car.
I’ve seen Fords and Chevys with 2 bolts holding the alternator on; one bolt will be SAE and the other a metric.
On the flip side you run into a Honda or Subaru that may require a 5/8 socket or wrench on certain things. (Seat belt attachment bolts for instance.)

Another downer is that while some SAE and metric tools interchange there is enough difference in the size to round off nuts and bolts.
A 14 MM wrench may fit a 9/16 bolt quite snugly but with the reverse a 9/16 may round off a 14 MM bolt head or damage it. This may show up later when the next person tries to free up that bolt that is now frozen.

Who says it has to change overnight? It’s been talked about since the 70s from my recollection. If we had really started back then it might be done by now. A journey of a thousand miles starts with the first step. If you never start…

If we consider road signs for example, they could have started with dual measurements on them and eventually changed over to only metric as they are replaced over decades.

Everything we design where i work is metric. All drawings, fasteners etc are metric. Sure we have legacy designs still in SAE our suppliers haven’t forgotten how to convert fer chrissakes!

Fractional fasteners? Simple, don’t design them in. Most of the fasteners in my late model cars are the same. 10mm is practically the only bolt size used on the interior. Makes sense in every way to use one size where possible.

If you really think the SAE system makes sense i ask you, why do you suppose we count in base 10 ( decimal)? Does it then make any sense to measure things in base 12?

" why do you suppose we count in base 10 ( decimal)?"

Probably because we have ten fingers. In fact, the word “digit” literally means finger in Latin.

“I can’t see any reason to or benefit from arbitrarily converting things to metric.”

I can think of at least one benefit. Listings in manuals for things like torque values would only need to be listed once, not twice. This means they could use less ink or toner, and have the option of less paper or larger print. It would be easier to read specifications in manuals and not confuse the values.

"Why do you suppose we count in base 10 (decimal)?

Had mankind invented the rotary power lawnmower before he developed the numeration system, we would be counting in base 9. When the rotary power mowers became popular in the 1950s, many people put their fingers under the mowers to determine if the mower was running. This is why mowers have safety handles that stop the blade when released.