This year will be the 45th anniversary of the Metric Conversion Act, which was signed on December 23, 1975, by President Gerald R. Ford. Normally, we celebrate by sharing metric education resources, but this year I want to use the occasion to dispel some common misconceptions about the U.S. relationship with the metric system.
You’ve probably heard that the United States, Liberia, and Burma (aka Myanmar) are the only countries that don’t use the metric system (International System of Units or SI). You may have even seen a map that has been incriminatingly illustrated to show how they are out of step with the rest of the world.
It’s a compelling story and often repeated, but you might be surprised to learn that it’s simply untrue!
While it’s true that metric use is mandatory in some countries and voluntary in others, all countries have recognized and adopted the SI, including the United States.
Russ Rowlett, retired University of North Carolina at Chapel Hill professor of education and mathematics, emphasizes on his website that becoming metric is not a one-time event but a process that happens over time. Every international economy is positioned somewhere along a continuum moving toward increased SI use. There are still countries that are amending their national laws to adopt a mandatory metric policy and others pursuing voluntary metrication.
The United States was one of the original countries to sign the Treaty of the Meter in 1875, which is now celebrated annually on May 20, World Metrology Day. It’s been legal to use the metric system since 1866, and metric became the preferred system of weights and measures for U.S. trade and commerce in 1988.
We use the SI every second of every day. After all, the second (s) is the SI base unit of time.
It’s impossible to avoid using the metric system in the United States. All our measurement units, including U.S. customary units you’re familiar with (feet, pounds, gallons, Fahrenheit, etc.), are defined in terms of the SI—and mass, length, and volume have been defined in metric units since 1893! The SI’s influence is pervasive and felt even if most people don’t know it. I envision U.S. metric practice like a huge iceberg. Above the water’s surface, U.S. customary units appear to still be in full effect. In actuality, below the water’s surface, we find that all measurements are dependent on the SI, linked through an unbroken chain of traceable measurements.
Although U.S. customary units are still seen alongside metric units on product labels and merchandise literature, it’s common for the goods themselves to be made using SI-based manufacturing processes. Why? While some businesses are concerned that consumers expect to see customary units on the package, when it comes to manufacturing processes, they are under constant pressure to stay competitive. Adopting the latest science and technology, developed using metric design practices, enables innovation. In addition, many industries extensively use international supply lines to develop, manufacture and sell their products around the world.
I’m the coordinator of NIST’s Metric Program. Because of my passion for all things metric, I encourage companies to investigate adopting metric practices whenever possible and show them how doing so can make a strategic economic impact for their organization. Changes in technology and extremely competitive domestic and global marketplaces can compel businesses with little previous experience to explore metric use. Many have found that going metric pays off, resulting in a competitive advantage.
During the recent recession, lumber companies located in the U.S. Northwest saw their U.S. customer base shrink, but their Canadian and Japanese markets, both of which use metric, expand—especially after the 2011 earthquake and tsunami. Wood-product producers made adjustments so that their production systems could flex between metric and U.S. customary measures based on what their customers needed. Because so much of the world uses metric only, more and more U.S. companies are recognizing the benefits of metric as they find new international markets for their products.
If your business is considering making the switch to metric, I would encourage you to conduct small beta tests to explore how your customers react. Research can help ensure decisions aren’t based on out-of-date information or preconceived notions. You might be pleasantly surprised by how quickly customers adapt—and how using metric benefits the bottom line.
And as always, if you need advice, be sure to give NIST a call. We’re here to help!
*Editor's note: This post was updated on October 6, 2020, to include information about units of measure for lighting, to include a new "metric continuum" graphic, and to make other minor changes. It was originally published on December 23, 2016.
Fantastically well put and I could NOT agree more with your assessment. Thanks for finding the words I seem unable to express.
אני אוהב אותך!!!!!!!!!!!!!
I must ask - how on God's green earth do you think Americans somehow invented our goofy method of measure we cling to so dearly? A large portion of USCS are throwbacks from the Roman empire, the remaining are edict of a king (um, the 'foot' and the 12 inch 'ruler'). If we were being honest and fair, we would've abandoned imperial (English) units for French (our staunchest ally in the Revolutionary War) just out of principal on or about 1790, as intended. Now, SI is not bound to any one nation. The kg and the meter (metre) have all been redefined using constants from nature. It is truly a system for all mankind and it's time we adopt it.
I don't know. I'm perfectly capable of using litres per 100km and I can figure out in my head how many more km's I can travel before running out of gas. It just took a little bit of flexing the brain muscles to acclimate to SI - but I'm in a small minority of Americans who seem to enjoy doing just that. On one hand, I'm glad I became fluent in SI on the other hand, being forced to use road signs in miles, feet and barleycorns makes me gag just a little bit knowing full well they'll never change. We are outliers here and we're rejecting what the rest of the world has acknowledged that SI is simply, unequivocally a superior way of measuring our world.
The map is accurate visualization of the commonly accepted senses of units by country. For example, those people in the three countries do not easily understand how long a 1-m stick is in general. Although SI is used in very limited areas by scientists and engineers, it does not mean the unit is accepted in the country. There are only two type of people; who tell their weights in kg, and those who use their traditional unit. There is no gray area in between them. The metrification continuum is a total myth. Go outside your country and see what other people do, because that is the only way to find out how absurd this article is.
Although the “metric map” has been elevated to a pop culture meme on the internet, it’s based on out-of-date information. This metric myth is rooted in an early map published in the 1971 U.S. Metric Study that depicted countries “uncommitted” to mandatory metrication. To see the historic map, visit the NIST U.S. Metrication FAQ website. Over the years, the term “uncommitted countries” has morphed into “non-metric” countries, a depiction that’s been used to criticize voluntary metrication by the United States.
If i ever start a business I will look into using the metric system. It look like i will make some money since it is no way around using the metric system everyday.
A nation of pig headed, recalcitrant citizens who for the most part seem blissfully unaware that any part of the globe exists but themselves. I feel terrible for kids in schools today. Especially those who may be inspired to join the scientific world. They claim they're teaching SI in American schools but the disconnected, chaotic 'real world' pressure of kings feet, barleycorns and Roman soldiers makes them soon forget what they've learned. Retaining our impractical, insular method of measure here in the US is a clear detriment to the future of our kids and their offspring. It is a foolish, quaint mish-mosh of nonsense. I'm in my 50's and still cannot conceptualize a "floz" vs an "oz", 12th, 8ths, 16th, 32nds of "inches", teaspoons, tblsp's, etc. It's absolutely confounding when you step back and objectively analyze it. I just use it because I am forced by American society to do so. I'm not overstating when I suggest that my own personal failure in the American education system was, at least in part, due to trying to grasp obtuse concepts like "American units" and relate them to each other. It's just not possible.
Both Myanmar and Liberia have made a decision to adopt the SI Metric System. The USA is literally alone as the only country on the planet Earth not making a serious effort to go metric.
The metric system is very good because when you are cooking you can use it to distrubute your ingredeints
Resistance to change is part of every human's DNA. It is part of what makes humans human. Some are more resistant than others. There isn't a right or wrong about the balance. There are several well documented reasons why people resist change.
(1) Complacency such as inertia or maintaining status quo
(2) Resignation such as anxiety the change is not an improvement and is viewed as a personal failure, or
(3) Cynicism or expectation the change result is not an improvement and viewed as someone else failing
Most resistance to change is rooted in Complacency. And most intentional progress is derived from organized efforts to overcome the complacent.
To the good people at NIST - don't get discouraged by those expecting failure. Work through complacency, gun your change engines, and get your KPH to a high rate of travel! :-)
Its 2020 and we still have huge differences in what should be a common understanding of measurement systems. Invisible borders is what halts our progress into the future.
One important field of activities extending worldwide - aviation, was not mentioned. No problem making the conversion here either. I have been flying (lawful) my glider in the US since 1996. All instruments are S.I. - Altimeter (m), ASI (kilometers/hour), variometer (M/s), etc. My flights are all VMC (Visual Meteorological Conditions) and I can't maintain a level as the IMC (Instrument Met. Conditions) like the big guys. This is adjustable and can be done. It will take time and money (many instruments) and reeducation, but it is doable. Time to start, like everything else..
By the way, I am very proud of my two 750Km (454.545mi) flights.
Time is not measured metrically. I have spent 49 years (omg almost 50 years now) as a metrology technician. 99 percent of my work still to this day is done in pounds, ounces, foot pounds, inch pounds, gallons quarts, etc. only electrical units of measure have been adopted as standards in use for my customers. Until the day we rework the day into 100 (some measurement unit) we will never be able to convert Time to a metric unit. This old man still prefers to use non metric units.
I cannot visualize metric units and must convert them to the measuring system that I grew up with before I know what the given measurements actually mean. I know that metric measures are useful and more precise, but they are of no use to me.
I was a child during the push to switch over to Metric and I can say one of the biggest mistakes was why the emphasis on converting back and forth! Fortunately, my time card in the military Metric is widely used and once I realized that if it is in Metric there's no need to convert! Also, I did a lot of traveling, abroad so the Metric System is natural to me. I use it whenever possible. My GPS I use Metric, phone temp Celsius, even my car most of the settings are set on Metric! I'm actually embarrassed that we are so slow with the changing, most people abroad look at us like we're idiots. At least I know the younger generations are being taught Metric properly,and most agree we should be using it. It's past time, and it's mainly the baby boomer generation that refuse to adapt, to change.