Why Do We Have Both Metric and Imperial Systems?

(Last Updated On: December 11, 2021)

Why Do we Have Both Metric and Imperial Systems?

If you’re American, you’ve probably had several fights comparing the metric and imperial measurement systems. Anyone arguing that America uses the imperial measurement system is actually wrong, however. America’s system is referred to as the “United States Customary Unit” system (USCU). The sentiment of the argument is still there though–so why hasn’t America adopted the metric system yet?

You probably know that only 3 countries in the world have yet to adopt the metric system. They would be the United States, Liberia, and Myanmar. This post will focus on America’s history with the metric system. We won’t be talking too much about how American culture gets in the way of moving to metric either. You can form your conclusions on how/why/if America tends to like non-American things or not. So with that said, let’s explore this topic a bit more in-depth. 

United States Customary Units Are Confusing

First, we need to start by talking about why people would even want to switch to the metric system in the first place? The answer to that lies in the fact that the US Customary Unit system is pretty much a mess.

For example, we have a bunch of different unites that use the same word–“ton”. We have short tons, long tons, displacement tons, metric tons, refrigerator tons, register tons, and more. That’s a ton of tons! They’re all completely different units in the USCU as well.

Adding to the confusion is the fact that not everything in the USCU is consistent. In America, engine output is measured in horsepower (non-metric). But the displacement of that same engine? Well that’s measured in liters (metric). In another example, we measure our football fields in yards, but our footraces in meters. It’s not very user friendly.

Compare that to the metric system, where everything works in tens. Makes sense, most people have ten fingers or ten toes, and most people tend to think in multiples of two, five, or ten. Imagine telling someone a millimeter is 1,000 times smaller than a meter, and a centimeter is 100 times smaller than a meter. Just slap another zero on there (or cut it off). But with the USCU, you get to explain how a foot is 12 times bigger than an inch, but a yard is 3 times one foot. You’re no longer allowed to just slap on zeroes. 

Temperature Might Get a Pass

To be fair, some may intuitively understand Fahrenheit better than Celsius. That’s because the former is meant to be in terms of human body temperature, setting a baseline at about 90 degrees. So you know how many degrees above or below 90 are uncomfortable or dangerous. 

Celsius is based on water, and while we’re made mostly of it, it’s easier to relate to being human than it is to being 100% wet. We’re ignoring that Fahrenheit uses an incorrect temperature as a baseline (if it’s really shooting for human body temperature). Yeah, fun fact, Fahrenheit was determined using very poorly calibrated instruments. 

We’re also ignoring that almost nobody else uses Fahrenheit, so the intuition only goes as far as America’s borders (as well as the Bahamas, Belize, the Cayman Islands, and Palau). 

Why Hasn’t America Gone Full Metric?

Americans, if you’re salty that the US isn’t all metric, you can blame the British. Way back in the 1700s, the Brits used their nonstandard units of measurement. At the time, this was the imperial system. It wasn’t a great time, weight being relative to stones or grains and all that. 

This measurement system was so bad that it’s addressed in the US Constitution. Article 1, Section 8 literally says Congress has the power to “To coin Money, regulate the Value thereof, and of foreign Coin, and fix the Standard of Weights and Measures.” While “fix” probably meant “standardize” rather than “the Brits can’t measure,” this still speaks to how poorly constructed measuring in America was when it was still an English colony.

So in the 1790s, Thomas Jefferson sought to standardize measuring in America. But before you get your pitchforks, there was a reason Jefferson didn’t immediately switch to the base-ten metric system.

By that time, the metric system was in its early incarnations, originating in France. As such, there wasn’t a lot of faith in the metric system, as it hadn’t been around long enough. Jefferson also wasn’t big on potentially having to pay the French to send a representative to make sure America was using the metric system properly. 

There was the added issue of Britain. While the French did help America during the Revolutionary War, America was beginning to mend relationships with Britain–something the French weren’t keen on. 

One final consideration today is the cost–going metric now would also be expensive. We’d have to replace a lot of engineering gear.

America is More Metric than You Might Think

America’s legislation has actually tried to go metric before, in 1866. The problem was that going metric was only presented as an option. It wasn’t made mandatory–so the push to go metric kind of fell flat on its face. Getting people to change their previous ways of thinking is tough!

But behind the scenes, a lot of things did go metric, especially in the way of international dealings. Why do you think your Coke comes in liters, or why is your camera described as 35 mm? We acknowledged that a little above, but that’s what makes America’s measurements so confusing. 

Think you know the metric system? Try your unit conversions here.

About the Author:

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Kyler is a content writer at Sporcle living in Seattle, and is currently studying at the University of Washington School of Law. He's been writing for Sporcle since 2019; sometimes the blog is an excellent platform to answer random personal questions he has about the world. Most of his free time is spent drinking black coffee like water.