An American perspective on the US metric transition

Earlier this year, Ronnie Cohen contacted the US Metric Association (USMA) to get information about the current situation in the USA regarding its transition to the metric system. Paul Trusten, Registered Pharmacist and Vice President and Public Relations Director of USMA, responded.

Ronnie put five questions to USMA about various aspects of the situation in the USA regarding metrication. Here are the questions and answers given by Paul.

1. What recent progress has there been in the USA in moving to metric?

As we often observe, metrication is happening “osmotically,” in spite of the U.S. lack of a coordinated national plan.  Prescription-only and over-the-counter oral liquid medications are being dosed more and more in millilitres only.  USMA members bring to light print and media articles that use only the metric system in text and illustrations.

2. What is the current situation in the USA regarding the measurement muddle between metric and US Customary units?

It continues to be “a very American mess” (worse, I think, than your “very British mess” as coined by that excellent UKMA report).  U.S. federal law continues to require both metric and customary units on product labelling. We do have a state regulation for metric-only labelling that has been adopted by all jurisdictions except New York State, but this has not yet gained influence across the nation in terms of policy.

3. How widespread are metric units on US road signs?

They are not widespread.  They seem to appear in a few places and only as old or new experiments. But when they do appear, it is usually alongside the customary units (miles as primary units with kilometres in parentheses).  A notable exception is a 100 km section of Interstate 19 in Arizona, from Tucson to the Mexican border.  All distance signs here are in kilometres only. However, speed limit signs are in miles per hour only.

You can find more examples of metric road signs on US roads at

4. What products are sold in rational metric sizes in the USA?

A diverse range of beverages, foods, health and beauty care products and cleaning products are sold in rational metric sizes (Source: This web page also gives examples of miscellaneous products sold in rational metric sizes.

5. How widespread is metric use in US industry?

As a result of US businesses manufacturing for and selling to world markets, where the metric system dominates, it is natural that much of US industry has gone metric. For example, the US car industry has produced cars entirely to metric specifications since the 1990’s, a typical example of the hidden use of metric units. It is ironic that US car manufacturers still advertise to US consumers in non-metric units, despite the fact that these units are not used for US car production at all. (Source: Jan/Feb 2016 Edition of ‘Metric Today’, the USMA newsletter.)

USMA gives several examples of US businesses that have gone metric. You can find them at

3 thoughts on “An American perspective on the US metric transition”

  1. What little metrication there is can be directly attributed to foreign ownership or influence in a company or direct importation of metric products from outside the US, especially from China and Germany.

    The automotive industry in the US is completely metric, both foreign and domestic. This also forces suppliers to accommodate metric designs. Business though that service both metric and USC customers will often use only enough metric to meet the metric requirements. If 70 % of the orders are for metric parts and components and 20 % for USC, the 10 % that doesn’t matter will most often be sourced as USC. Even products that have a complete metric pattern will be described by a USC equivalent description.

    Modern automotive factories tend to be highly automated and hire very few workers. This means less and less of the population exposed to metric units on a daily basis.

    Schools don’t often teach the metric system as a stand-alone system but through conversion factors. American kids are taught to convert metric units encountered back into USC. Thus metric is loathed as it is a pain to have to convert.

    Metric phrased questions or answers to questions often result in “What’s that in ‘merican?” or “That’s blah-dee-blah in standard”.

    Unlike the growing strength in German Mittelstand companies, US small business manufacturers continue to struggle and subsist on the edge. Having to deal with metric more often than they wish, American products end up being a hybrid of metric and USC components.

    The muddle is very costly, but no one focuses on it, focusing only on the one-time cost of metrication.


  2. @Daniel:

    “The muddle is very costly, but no one focuses on it, focusing only on the one-time cost of metrication.”

    Indeed. The late Pat Naughtin many years ago estimated that working in non-metric alone (never mind any conversions) costs the US economy millions of dollars per day (amounting to, if memory serves me correctly, around US$1trillion – EVERY YEAR!). But this cost is totally hidden, so nobody either believes it or even acknowledges it.

    I read just recently that a majority of US families live on the financial edge. Some 47% of families would have trouble finding a mere $200 to fund an emergency, and over 80% would not be able to respond to an emergency cost of $1000.

    We can only speculate as to how much being non-metric contributes to this situation (much of it may be caused by other economic conditions that increase the disparity between rich and poor, squeezing out the middle classes), but I do believe that the USA is suffering an overall decline it its living standards, as newer nations, especially those in the far east, gradually overtake America. These are metric nations, making, selling and buying metric goods between each other as well as to and from the rest of the metric world. Will the USA eventually wake up to this?

    I see parallels with Britain 100 years ago, in the days of the empire. We sold goods to the whole world, especially other Commonwealth countries, and became very smug and complacent as a result. It is an attitude we still see in the UK today (exemplified by the ‘Brexit’ movement, still thinking that the UK can go back to how it was – it can’t). Has the US also fallen into this way of thinking?


  3. From NASA today, news of the first tool to be 3D printed on the space station.
    Regrettably the nut sizes are all in inches, 1/4, 3/8, 1/2, 5/8 and presumably AWG wire sizes of 8, 10, 12, 14. It is like looking at an artifact from the 1960’s !!!
    So much for the metric space programme. But then I guess due to the age of the ISS it would be a hotch potch of mixed and muddled measures anyway.


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