Confoundingly, the U.S. has stood on the sidelines for centuries as the rest of the world has adopted the metric system as its standard not only in science but in everyday life. (Meanwhile, we struggle in the kitchen to convert tablespoons into milliliters.)

Curious as to why that is, we reached out to numeracy advocate and Temple University professor of mathematics John Allen Paulos for an answer.

Why is the U.S. still one of only a handful of countries around the world to not use the metric system?

The world is full of questions we all want answers to but are either too embarrassed, time-crunched or intimidated to actually ask. With Infrequently Asked Questions, we set out to answer those shared curiosities.



There isn't even a handful of countries that haven't officially adopted the metric system. Only three countries — the U.S., and its fellow scientific powerhouses Burma and Liberia — have all not. Why the U.S. hasn't is a bit of a mystery. Part of it is our federal system and a lack of government centralization. Part of it, too, might be a kind of American exceptionalism in the realm of science.

There was an effort to convert back in the ‘70s that didn’t go so well. What happened there?

It ran up against the obstacles just mentioned and plain old societal inertia. Without a mandate to change, the switch over to metric has been very slow — metaphorically, in millimeters per year.

Where did our customary system come from, anyway?

It developed over time in different countries and resulted in a hodgepodge of units — pounds, stones, pints, gallons, inches, miles, bushels, et cetera. This led to a clear need for universality if trade and commerce were to progress beyond borders and regions.

Presidential hopeful Lincoln Chafee, most recently, was a (relatively) high-profile political figure who proposed conversion to the metric system, and he got flak for it. Why is it such a controversial thing to be pro-metric system?

I think the metric system is perceived by some as tantamount to being ruled by Europe and the rest of the world. (Think of Brexit and the fact that the British do backslide a bit with 'pints' and a few other units.) I also think opposition to it is related to garden-variety innumeracy and traditional American anti-intellectualism. It didn't help either that Chafee came across to some as a bit of a nerd.

Are there costs — tangible or intangible — to not using the metric system?

Yes, definitely. Math and science students aren't developing a visceral sense of the size of various quantities expressed in the international system of measurement, in the same way tourists abroad are always wondering whether 30 degrees Celsius (centigrade) indicates a hot day or not. Our system can also lead to more than a brief confusion, as occurred when NASA lost the Mars spaceship because of a discrepancy between the units used by the ship's contractors and the metric units used by NASA.

Why, in a nutshell, is the metric system actually the ideal system of measurement?

There are two reasons. The first is universality, the motivating factor in the development of the metric system as the French philosopher [Marquis de] Condorcet argued in the 18th century. The second reason is that the units are based on our base 10 number system and are, therefore, easily compared via common prefixes, unlike our customary system. There are 1,000 millimeters in a meter, 100 centimeters in a meter and 1,000 meters in a kilometer. Likewise, with milligrams, centigrams and kilograms, as well as joules, liters, newtons, watts and other notions from physics and everyday life.