Why the U.S. Should Convert to the Metric System

by | Mar 22, 2021


What do Liberia, Myanmar, and the United States have in common? They are the only three countries that haven’t adopted the metric system.

I was born in 1970. I recall as an elementary school student in the late 1970s and early 80s being prepped for America’s conversion to the Metric System. But then the push to convert fizzled and 40+ years later we still (mainly) use the imperial system (or, actually, the U.S. customary system). What happened?

A Quick History of The Metric System in the U.S.

Why the U.S. hasn’t adopted the Metric System is multifaceted, but basically boils down to the fact that Americans don’t want to. Even though founding father Benjamin Franklin helped develop the Metric System and Thomas Jefferson supported the U.S. using the Metric System, the movement never caught hold because 18th Century Americans viewed the Metric System as being too French. Between 1790 and the Civil War, the idea of going metric was tossed around as a political football but never received enough support.

In the wake of the Civil War, the U.S. legalized the use of the Metric System via the Metric Act of 1866 which is still a valid law on the books (which means you can go ahead and use the Metric System to your heart’s content in the U.S. and not break any laws). The post-Civil War metric movement sputtered out in 1870 when U.S. manufacturers blocked the conversion because of the high retooling cost of moving to metric units.

In the 1970s the Metric System movement in the U.S. was rekindled and resulted in 1975’s Metric Conversion Act which established the Metric Board which would guide America’s transition from the U.S. Customary System to the Metric System. Because of the Metric Conversion Act and the Metric Board, from 1975 to 1982 there was a push to move to metric. For example, car speedometers and highway speed limit signs began to show both MPH and km/h (and some used only km/h as I-19 between Tucson and Mexico still do).

Then in 1982, responding to public opinion, Ronald Reagan dismantled the Metric Board and the push towards the metric system died. Support for moving to the Metric System appears to be political suicide. Case in point is Rhode Island Senator Lincoln Chafee’s 2016 Presidential run. He proposed moving the the Metric System as part of his platform and was roundly criticized and ridiculed. Having Metric System adoption as part of his platform was wildly unpopular and his Presidential hopes were dashed.

American Aversion to the Metric System

Americans tend to view the Metric System as awkward and strange. Initially it would be unusual to switch over. I’d have to think of my weight as 79.3 Kilograms rather than 175 Pounds and my height as 175 centimeters instead of 5’9″. I’d think of my commute as 1.2 kilometers rather than 0.8 miles. Grabbing 50lb dumbbells would switch to 22 kg dumbbells. Right now I’d think of the temperature as 5 degrees Celsius rather than 41 Fahrenheit.

In addition to the switch being awkward, we Americans like to chart our own path. Back in the late 18th century we viewed the Metric System as too French. Public opinion since then reflects that we view the Metric System as too foreign and too European. Using the US customary system seems uniquely American and we love being unique.

Why We Should Use the Metric System

Sometimes public opinion is just wrong (insert your own example here ___________________). Our retiscence to switch to the Metric System is a good example of misguided public opinion. Here are just a few reasons why moving to Metric would be good for the U.S.:

1. Going Metric Would Reduce Errors. Because the rest of the world uses Metric, our need to convert leads to mistakes. A good example of this is the destruction of the Mars Climate Orbiter in 1999. The satellite was intended to orbit Mars at 150 km in altitude but descended instead to 57 km and burned up. The mistake was caused by miscommunication between the spacecraft’s software which used Metric and the ground crew who used U.S. customary. Even where mistakes don’t occur, the need companies to convert Metric to U.S. customary creates additional expense and hassle.

Drug misdoings are a prime example. The ECRI Institute, which studies effective medical procedures and processes, listed medical errors due to Metric/Customary conversion mistakes as the No. 7 concern of their Top 10 Patient Safety Concerns. Development and distribution of drugs is global. For example, the Pfizer COVID vaccine was developed by BioNtech, a German Company. Converting patient weight from pounds to kilograms creates an opportunity for mistake and giving a patient the wrong dose of medicine.

2. The Metric System Just Makes More Sense. If you were starting from scratch you wouldn’t use the U.S. Customary system. Why do we have 12 inches in a foot and three feet in a yard? Why 5,280 feet (or 1,760 yards) in a mile? Why are there 8 ounces in a cup and 16 cups in a gallon? Why 16 ounces in a pound? Water freezes at 32 degrees and boils at 212. It’s a bizarre hodgepodge of units and subunits. We are used to it so maybe it doesn’t seem strange, but it’s akin to what it would be like if we had 15 pennies in a dime and 8 dimes in a dollar.

The Metric System is all based on tens. There are 100 centimeters in a meter and 1000 meters in a kilometer. Likewise, there are 1000 grams in a kilogram. And so on. This makes A LOT more sense than the U.S. customary system that has no consistent convention for units and sub-units. Here’s a summary of the metric system unit convention:


3. It would Make Life Easier. Switching would be hard, but from then on using the Metric System would be easier for all of us. Teaching children about units and sub-units by moving the decimal right and left is a lot easier than our current system. When I cook I often have to pull out my phone and ask Google how many teaspoons are in a tablespoon. When my GPS says I turn in 800 feet I am confused about how far that is — is it closer to a quarter mile or a tenth of a mile? And so on.

According to Vox, “The metric system makes back-of-the-envelope calculations far easier for, say, making a solution in a laboratory or calculating the area of a parking lot or figuring out how many pills to give someone of a particular body weight. It also makes it quicker to double-check a calculation that a computer just spit out.”

We Do Use the Metric System Some

Switching over wouldn’t be as hard as you might think. In some areas of our lives we do use the Metric System:

  • For example, common lengths of running races are 5Ks and 10Ks. If you are a runner, you’ve digested what a 5K feels like.
  • We buy some drinks by Metric measurements. Examples are 2 liter bottles of soft drinks and 750ml bottles of wine and spirits. So, if you are a wine drinker you have a feel for how much liquid 750ml is.
  • The Metric System is the primary unit of measurement in the medical field. For example, the Pfizer Covid vaccine dose is 0.3ml and IV bags are typically 100ml.
  • The U.S. Military uses mainly metric measurements to ensure compatibility with allies.


  1. Switch to Metric: “It’s 1000 times easier!”

    After successful preparation Australia converted their road systems from miles to Kilameters (*) in one weekend back in the 1970s.

    They actually recorded fewer traffic accidents for a few weeks.

    Check out:




    For and example of quick and successful metrication in Australia.

    I’m an American and I wish America would do the same.

    George Washington implored Congress 3 times to do their job on Units and Measures as detailed in the U.S. Constitution and switch to the Metric System.

    (*) I would like to suggest a couple of changes to improve the Metric System such as Kilameters instead of Kilometers to match the ending -a in the rest of the Magnifying Metric Prefixes.

    • I could see Americans embracing the metric system if there was a metric “foot” unit. Americans love their foot and feet. There’s nobody in the US that wants a metric USA more than me but I will admit that for any unit under a metre (meter) that would be the biggest hurdle for the average foot loving yank. The best advice is DO NOT CONVERT. Learn to intuitively use the units and it is NOT that difficult. Dumping Fahrenheit was easy. It took about a week before I would break a sweat just seeing a 40° temp in the forecast. Now, f looks utterly bizarre to me.

  2. One also forgets the building codes are all in Imperial units, as well as the extensive tooling industry. In addition, the conversion from miles to kilometers will have to be done VERY carefully, as speed limits in kilometers will be confused as miles, so that drivers would routinely be going nearly double the posted kilometer limit. For instance, a street marked as 60 kph is actually 37.2 miles per hour. By the way, the vast majority of speeding tickets given in Canadian border towns are to Americans who commit this every error. I would estimate hundreds or thousands of deaths and hundreds of thousands of injuries per year would result from conversion errors alone.

  3. My question is who is the author of this article ?

    • I am

  4. America – Don’t fear change. Going metric will only benefit you in ways you’ll never be able to understand until you’re there. First off – every 3rd grader on every other nation is better prepared for science and engineering than the average American HS graduate. Don’t you want to move into the future (well, for you it’d be the future) instead of slogging along in the 9th century?

  5. We here in Britain have been taught the metric system in schools for the last 60 years or so. Despite this, if you speak of a man 1.78 metres (or 178 centimetres) tall, your hearer will in 95% of cases have no idea whether you are referring to a dwarf or a giant. Everyone can visualise half a pound of cheese, but 250 grams? The French under Napoleon invented the metric system and yet the French still refer to 500g as “Une livre” (a pound).

    • Yes, the British adopted some of the metric system in `1971, e.g. for currency and temperatures, but not for driving distances or beer. But the currency change was a huge improvement. I still have nightmares as a five-year-old trying to subtract £3 15s 11d from £5 4s 3d.

    • And your point is? And, who is “everyone” who can visualize half a pound of cheese? That’s a pretty broad remark. Everyone who is still using units from the days of Caligula, maybe – but that was a different epoch. We shouldn’t be dragging the 9th century around in the 21st. Why is the US and UK so hung up on catering to obdurate luddites?

  6. My 12 year old boys were telling me 3 weeks ago that adults intentionally make their lives harder by making up more complex rules – such as the US measurement system.


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