Metric system

Last updated on August 26th, 2023 at 12:51 am

A vernier scale is a visual aid to take an accurate measurement reading between two graduation markings on a linear scale by using mechanical interpolation; thereby increasing resolution and reducing measurement uncertainty by using Vernier acuity to reduce human estimation error
Photo by Ag PIC on UnSplash

The USA, along with 40 other countries signed the the Treaty of the Meter in Paris in 1875. In the late 1960s, both the US and Canada decided that continued use of the Imperial system of measurements, or inch-pound system in the US, didn’t make sense since the rest of the world worked and lived in the SI Metric system. If you were in grade school in Canada during the early 70s like I was, you will remember learning both systems.

Failures in conversion lead to mistakes

Violet will never be able to instinctively judge temperatures in Celsius, she wasn’t raised to. And being raised without the metric system is like being born with weights on your brain.

In metric, one milliliter of water occupies one cubic centimeter, weighs one gram, and requires one calorie of energy to heat up by one degree centigrade, which is 1% of the difference between its freezing point and its boiling point. And amount of hydrogen weighing the same amount has exactly one mole of atoms in it. Whereas in the American system, the answer to “how much energy does it take to boil a room temperature gallon of water?” is Go fuck yourself, because you can’t directly relate any of those quantities.

Wild Thing – Josh Bazell

The US gave up on conversion to SI Metric, at least in part because replacing all of the speed limit signs and milage marker signs with new signage showing the metric limits was just going to be too expensive. In 1999, the Mars Climate Orbiter burned up in the Red Planet’s atmosphere because of a unit mix-up between NASA and Lockheed Martin [1]. Today, only the United States, Liberia, Myanmar and a handful of island nations use versions of the imperial system [2], [3], [4].

Canada completed the transition but requires dual unit markings on product labels. Many Canadians continue to cook in Imperial measures (cups, quarts, teaspoons and tablespoons) while driving in km/h and deciding what jacket to wear based on ºC, but set their thermostats using ºF.

The consequences for Canadians include tape measures and rulers with both inches and millimetres, dimensional lumber only measured in feet and inches, i.e., a 2 x 4 x 8′. Dimensional lumber is smaller than the “trade size,” just to make things a bit more confusing. A 2 x 4 is actually 1-3/4″ x 3-1/2″. Sheet lumber, like plywood and OSB flooring, has the thickness measured in millimetres, but the sheet size in feet, i.e., 4′ × 8′. The confusion continues in many other materials as well. But I digress.

Failure to progress

In 2022, then Prime Minister Boris Johnson of the UK announced that he intended to rescind the UK’s conversion to the metric system in favour of reversion to the Imperial system of weights and measures [7]. This is yet another example of mindless decisions made on purely populist ideology since most of the UK’s business is done with metric countries in the EU and elsewhere. As Mr. Johnson is no longer the PM, this particular bit of madness may have passed the UK by. Unless, of course, Prime Minister Rishi Sunak decides that Mr. Johnson had a good idea.

Why convert to metric

For the most part, science and engineering are done in SI Metric, even in the USA. Medicine using SI Metric as well, again, except in the USA. At some point, I hope that the idealistic hold-outs recognize that clinging to obsolete systems of weights and measures does nothing but hamper trade and innovation. Still, I doubt that such logical thinking will prevail before the end of my life.

Hope is the thing with feathers
That perches in the soul
And sings the tune without the words
And never stops at all.

Emily Dickinson


[1] “Math Error Equals Loss of Mars Orbiter”, Science News, 1999. [Online]. Available: [Accessed: 18- Jun- 2022].

[2] “Countries That Don’t Use the Metric System 2022”,, 2022. [Online]. Available: [Accessed: 18- Jun- 2022].

[3] C. Martin, “The U.S. has resisted the metric system for more than 50 years”, Science News, 2020. [Online]. Available: [Accessed: 15- Jun- 2022].

[4] “Supporting American Choices on Measurement | We the People: Your Voice in Our Government”,, 2012. [Online]. Available: [Accessed: 18- Jun- 2022].

[5] “Ten Years to Metric”, Science News, 1970. [Online]. Available: [Accessed: 15- Jun- 2022].

[6] P. Gallagher, “Make the Metric system the standard in the United States, instead of the Imperial system.”, We the People, 2012. [Online]. Available: [Accessed: 15- Jun- 2022].

[7] “Boris Johnson to reportedly bring back imperial measurements to Mark Platinum jubilee,” The Guardian, (accessed Aug. 25, 2023).


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