Illustration of a truck filled with road signs while construction workers place them on highway

Illustration by RJ Matson; Shutterstock.com (background)

Should We Switch to the Metric System?

Is it time to abandon inches, feet, and miles?

By Mackenzie Carro

From the February 2024 Issue

Learning Objective: to read and analyze a text that presents arguments on both sides of a debate, then take a stand

Lexile: 900L

Featured Skill: Argument Writing,

Other Key Skills: identifying central ideas and details, evaluating an argument, using text evidence

Listen to this debate read aloud.

In 1983, an airplane in Canada ran out of fuel mid-flight. The pilot made an emergency landing, but two people were injured.

In 1999, a NASA satellite that cost a whopping $125 million suddenly broke apart on its way to Mars.

And in 2003, a roller coaster at Tokyo Disneyland flew off the tracks. No one was hurt, but the ride had to close for two months.

These accidents have something in common—and it’s not bad luck. They were all caused by math mistakes!

The mistakes had to do with using two different systems of measurement: customary, which is what we mainly use in the United States, and metric, which is used just about everywhere else.

For decades, Americans have debated whether the U.S. should stop using the customary system and switch to metric exclusively. In fact, Congress even passed a law in 1975 saying metric was the preferred system. Still, metric units didn’t fully catch on.

Some say we should switch because the metric system is easier and more widely used throughout the world. They point out that many fields—from science to health care—already use it. Others argue that switching would be too expensive and even dangerous.

Your Life Would Be Easier

Seregam/Shutterstock.com

Humans need a standard system of weights and measures so we can understand each other when we talk about how much things weigh or how far one place is from another. In the U.S., customary is the system we’re all familiar with. Miles mark the distance from your home to your school. Cups measure the sugar in your cookie dough. Feet and inches show how tall you’ve grown.

But the U.S. is one of only a handful of countries that don’t use the metric system for everything. That means if you were growing up just about anywhere else, your milk would come in liters. Your school’s football field would be measured in meters.

And your life would be so much easier! Here’s why: Because it’s based on units of 10, the metric system is very simple. There are 10 millimeters in a centimeter, 100 centimeters in a meter, 1,000 meters in a kilometer, and so on. To convert one unit to another—grams to kilograms, for example—you simply need to memorize a few prefixes and learn to move decimal points around.

That’s it!

Customary units, by comparison, are totally confusing. You have to remember that there are 5,280 feet in a mile, 4 quarts in a gallon, 16 ounces in a pound, and much more. If the U.S. went fully metric, you wouldn’t have to bother with any of that.

Plus, “converting back and forth between the two systems can lead to errors that have practical consequences,” says Elizabeth Benham of the National Institute of Standards and Technology.

Indeed, the fact that the U.S. uses customary in everyday life and metric in fields like science and health care has caused plenty of confusion in the past. That satellite disaster? It happened because the company that built the satellite was using customary units for certain calculations, while NASA was using metric.

And that coaster derailment? It was due to a small part that was sized in customary units when the rest of the coaster had been sized in metric.

Money and Effort

Eddie J. Rodriquez/Shutterstock.com

Unfortunately, going metric would take a lot of money and effort. The next time you’re in a car, count how many speed limit signs you see. Every one of those signs would have to be changed from miles per hour to kilometers per hour—and so would every sign on every city street, country road, and freeway across the nation.

We only have to look to Canada to get a sense of what switching would take. Canada went metric back in 1970. It took about 15 years and more than $1 billion to update everything.

Switching could be dangerous too. Remember that plane mishap back in 1983? It happened during Canada’s transition to the metric system. The calculation for how much fuel was needed was accidentally made using pounds instead of kilograms. As a result, there wasn’t enough fuel.

What problems could occur in the U.S. during a similar transition?

One possibility is an increase in traffic accidents. U.S. drivers have a sense of what 65 miles per hour feels like. But what about kilometers per hour? It would take time to adjust. In the meantime, accidents could become more common.

What’s more, online converters have made the customary system less of a hassle. Customary units are even woven into our language. Think about expressions like “inching along.” “Centimetering along” just doesn’t have the same ring, does it?

So what do you think? Should we give up inches for centimeters? Or stick with what we’ve got?