The Cost of Outdated English Units
Burma, Liberia, and the US. Three countries that you don’t normally hear grouped together in the same sentence. None share a continent, many would have trouble locating all three on a map. Yet there they are. The reason I have gathered these countries together in the opening sentence of this essay is that these are the only three remaining countries on the Earth that have not adopted the International System of Units, better known as the metric system.
Ease of Use
But wait, fractions are so much easier in a base twelve system! This breaks down as soon as you want a third of an inch, instead of a third of a foot. Sure base twelve is great for dividing, but why is there base two system in there, too? Where are the benefits of a base twelve system in the fractions of an inch?
And of course it makes perfect sense to measure distance in miles, the most intuitive unit of distance. Why what is a mile you ask, 5280 feet! It’s easy to remember, you see. A mile is eight furlongs, the length of a furrow that a team of oxen could plow in a single day, which is 660 feet. And the English Parliament decided in 1592 that was close enough to the 5000 roman feet that originally defined a mile. So if you ever forget, just remember that it is a close approximation of 1000 paces of the average roman man, rounded to eight times the length that a team of oxen can plow in a day.
The point is, decimal systems are pretty well engrained into Humans. We have ten digits. Our numbering system is base 10. The idea of a system of units that conforms to this intuition makes for a simpler and more efficient system of measurement.
Think of the Poor Scientists and Engineers
And if those reasons aren’t enough, I can personally attest that being forced to occasionally work in customary units is terrible. I hate having to convert between slugs, oz-inches, pound-mass, and pound-force (those last two mean shockingly different things depending on what planet you are on). They are not intuitive, and they are bound to make any engineering student groan. Myself and many others would rather convert entire problems to SI units and back, instead of using the customary units thrust upon us by society.
The difficulty in dealing with multiple systems of units has caused a number of failures over the years. The most famous, and likely most expensive, of these mishaps is when NASA lost a Mars orbiter due to a unit conversion error. This failure cost NASA $327M, which could have been resolved if the United States used the metric system.
Costs of the Customary System
There is a cost to the time it takes to convert units. This is both an issue for Americans dealing with themselves and when dealing with other countries. Converting millions of inches to miles takes time, and that time is needlessly wasted on an archaic system of measurement. Time is wasted every time a transaction occurs for materials, or plans are made between entities. All of these seconds add up, and the longer we go without switching, the more time and energy will be wasted. J. V. Collins estimated in 1915 that the US was losing $315M a year from a lack of conversion, counting for inflation this would come out to $8.1B lost annually in 2020.
There is a cost to maintaining different standards for SI and customary units. Machinists need capabilities for two types of threads, which each have multiple thread specifications.
To add to the frustration, we actually use SI units every day. Not even in the cheeky “seconds are SI units” way. By definition, every inch, milk, gallon, and pound that is ever measured, is actually measured in reference to the corresponding SI unit. Ever since the International Yard and Pound Agreement of July 1, 1959, customary units have been, by definition, calculated from a standard in the metric system. Where scientists have been able to define SI units in terms of physical phenomena and first principles, there don’t seem to be any that work in customary units to have done the same. So not only should we switch to the metric system, but it is actually foundational to the system we are already using.