Monthly Archives: February 2013

The “Preferred” Measurement System of the US

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By The Metric Maven

Bulldog Edition

The object to the left is an everyday thing, but it is making a clear statement about the designer’s measurement preference. It may not be apparent what the measurement preference is to you. It might not have been to me had I not read The Design of Everyday Things by Donald A Norman (suggested to me by Sven). The design of even the simplest of objects is done in a manner that provides information on how the designer intends them to be used. A person will unconsciously take an intended design clue, and use an object as intended. Knives are provided with handles, and one doesn’t stop to think which is the best end to hold in one’s hand after early experience and instruction in childhood. Norman cites research which argues there are at least 30,000 everyday things around us, and decreases the number to 20,000 to state: “Suppose each everyday thing takes only one minute to learn; learning 20,000 of them occupies 20,000 minutes —333 hours  about 8 forty hour work weeks.” We have a considerable amount of time invested in learning about our everyday things. When we encounter a can opener, or a scissors, or a potato peeler, we generally know exactly what to expect, how to hold it, and how to use it. One way that a designed object signals how it should be used, is to design it so the ways it may be used are limited, this is called affordance by Norman.

When I worked on the design of televisions, I immediately ran into the idea of affordance. A television motherboard and its chassis were dropped off in my lab, but about seven cables had been disconnected. I protested that it was all apart, and was calmly told by a technician  that all the plugs would only go into one place on the motherboard. Indeed, they did, and I was impressed that because of this affordance, I couldn’t make a mistake.

The affordance of the TV motherboard was essentially foolproof, but often designers can’t restrict a user that much, and the affordance involves only discomfort or a subtle tactile clue. Donald Norman offers this:

Take another example of good design. My felt-tipped marking pen has ribs along only one of its sides; otherwise all sides look identical. Careful examination shows that the tip of the marker is angled and makes the best line if the marker is held with the ribbed side up, a natural result if the forefinger rests upon the ribs. No harm results if I hold the marker another way, but the marker writes less well. The ribs are subtle design cue—functional, yet visibly and aesthetically unobtrusive.

Norman also shows numerous door handles as examples. If we see only a push plate on a door, we have no other choice but to push to open the door. A handle which one can readily grasp cues us that we pull to open it. This brings us back to the measuring cup shown above. Its design is pro-metric, as the metric graduations are facing a person’s eyes when it is held with the right hand. About 70-90% of the worlds population are right handed. Right handed Americans using this measuring cup, would find it uncomfortable and unnatural to place the handle on the left. The measuring cup shown is from the period when the US pretended it might go metric. Measuring cups of this same type, which are currently sold in the US, are all designed so that the imperial graduations face one’s eyes when held with the handle on the right. One of mine is shown below:

Common American Measuring Cup

Measuring cup designs have improved since the 1970s. Some of the ones I now own are “top readable” and only sold (unfortunately) at product parties. Dual scale is always a hindrance to metric adoption, but this set of top reading measuring cups are the best I have encountered.  I have visited many cooking stores and looked online, but have yet to find metric-only measuring cups and measuring spoons. The measuring cup shown below appears to have eliminated a right hand bias as well as being easy to read. Now if I could just purchase a metric-only one.

Top Read Measuring Vessel with Clear Metric Graduations
Left Handed Ruler

The design of common measuring cups is but one example of subtle anti-metric bias in our everyday things. In a previous blog I mentioned that the design of American “metric” rulers hinders their use because of the presence of a centimeter-millimeter dual unit scale, and the rounding of the origin end of one particular metric scale. The origin of the inch scale is placed on the square end, which is much more natural for measuring. For about 10% of our population, which are left-handed, the current dual scale measuring cups are adequately designed for metric use. On the other hand both metric and inch ruler scales  have equally low affordance for left-handed people. Left hand rulers exist which have the numbering from right to left to increase the ease of use by a left handed person.

My father gave me an expandable wrench for my last birthday, which has mm markings on one side, and had inch on the other (yes, I ground off the inch scale). If one holds the wrench as a right handed person would, the inch scale faces your eyes. On the opposite side is the metric scale, which has low affordance for a right-handed person. The wrench is nice because it allows one to immediately see what size a bolt head is in mm, but it is very cumbersome for me to use, as I’m right handed.. I have a better understanding of what left handed people deal with on an everyday basis in our world.

Expandible wrench designed with an affordability preference for inches (click to enlarge)

These examples point to the fact that a preference for imperial measures is designed into our US tools, and US everyday things. But I’ve been assured by non-binding legislation that the US prefers metric measurements. Here is some background:

The Omnibus Trade and Competitiveness Act of 1988 was signed into law by Ronald Reagan. It amended the Metric Conversion Act of 1975, yet didn’t have the word metric in the title of the legislation. President Reagan and Congress apparently were concerned that the voluntary nature of the Metric Conversion Act of 1975 was not clear enough.

Section 3 of the Metric Conversion Act of 1975 is amended to read as follows:

SEC. 3. It is therefore the declared policy of the United States

(1) to designate the metric system of measurement as the preferred system of weights and measures for United States trade and commerce;

(2) to require that each Federal agency, by a date certain and to the extent economically feasible by the end of the fiscal year 1992, use the metric system of measurement in its procurement, grants, and other business-related activities, Except to the extent that such use is impractical or is likely to cause significant inefficiencies or loss of markets to United States firms, such as when foreign competitors are producing competing products in non-metric units;

Well, it has been the case since the 19th Century, that switching to metric is always “impractical” in the US. Apparently there was much concern among our legislators that we have an exception: “such as when foreign competitors are producing competing products in non-metric units;” Apparently Liberia and Myanmar (the last two non-metric holdouts in the world) might flood the US (and the world?) with non-metric products, and thereby destroy what’s left of our uncompetitive non-metric US economy. Thank you President Reagan and Congress for the foresight to see the threat and protect us from the economic danger posed by these two tiny countries, and making an exception. Clearly the 1992 date was meaningless and arbitrary. It made it look like the government was taking action, when in fact it was not. Metric is 21 years past the expiration date for becoming “preferred.”

One can easily see how “preferred” metric is in the US simply by inspecting the design of our everyday things and everyday tools. The legislation is feckless, and crass hypocrisy. It is in line with the strange belief that if we cling onto the trappings of our past, the future may be indefinitely postponed. This emotional response, written in legislation, only postpones the day when reality intervenes, and forces Americans to realize that fantasy is no match for reality. I’m not willing to wait another 150 years hoping America will come to its senses. We need legislation that compels industry to design and make available true metric products, during a short compulsory switchover by industry, government, and education to metric. What we have now is legislation celebrating the the metric system as the preferred system of the future and makes sure it will always remain so.

Related Essay:

The Invisible Metric Embargo

If you liked this essay and wish to support the work of The Metric Maven, please visit his Patreon Page and contribute. Also purchase his books about the metric system:

The first book is titled: Our Crumbling Invisible Infrastructure. It is a succinct set of essays  that explain why the absence of the metric system in the US is detrimental to our personal heath and our economy. These essays are separately available for free on my website,  but the book has them all in one place in print. The book may be purchased from Amazon here.


The second book is titled The Dimensions of the Cosmos. It takes the metric prefixes from yotta to Yocto and uses each metric prefix to describe a metric world. The book has a considerable number of color images to compliment the prose. It has been receiving good reviews. I think would be a great reference for US science teachers. It has a considerable number of scientific factoids and anecdotes that I believe would be of considerable educational use. It is available from Amazon here.


The third book is not of direct importance to metric education. It is called Death By A Thousand Cuts, A Secret History of the Metric System in The United States. This monograph explains how we have been unable to legally deal with weights and measures in the United States from George Washington, to our current day. This book is also available on Amazon here.

The American “Metric” Ruler

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By The Metric Maven

Bulldog Edition

Early in my metric-only odyssey I learned some metric lessons the “hard way.” Because of my  inexperience, I had a naïve view of metric implementation that caused me to be incautious. My better half decided she would try using metric for some of her craft work. She flipped her ruler over to its metric side and began using it. I thought nothing of leaving her alone to work, after all metric is simpler—right?  Within a few minutes she was complaining that the pattern she was working on was 1.5 mm long and she needed it to be larger.  I had seen the pattern and it was way larger than 1.5 mm. Incredulously I walked into her study, looked at the pattern, looked at the ruler and realized it was more like 15 mm in length. I inquired how on earth she measured 1.5 mm, she quickly showed me the marking on the ruler, and I realized that according to the ruler, she was indeed measuring 1.5 mm. Here is the end of that ruler.

Ruler which indicates mm graduations — But cm are numbered

One notes that it is labeled millimeters, and therefore one would expect, that like inches, each numbered mark, 1, 2, 3 and so on would be in millimeters!  I looked at it in astonishment, and realized that anyone not familiar with the metric system could easily make this mistake. I explained the situation that the large marks are centimeters and the small divisions
are millimeters. It was my first realization that American “Metric” Rulers (AMR) actually had two units, and the imperial side only used inches. Until I actually started using metric exclusively, I had never noticed this. One of my biggest complaints is the common mixing of units in imperial. For instance a person’s height might be 1 yard, 2 feet, 10 inches and 1 barleycorn tall. Ok, we have simplified this to just 5′ 10 1/3″ but that’s still two units–designated with quotation marks. The use of multiple units is a clear violation of Naughtin’s Laws and only serve to obfuscate the experience of a direct cognitive understanding of magnitude.

Centimeter label with cm designations

I realized that the  ruler should say cm instead of mm. This caused me to start looking at rulers offered in office supply stores. It is there, one can see that the metric side of a dual-scale ruler gets little respect. For instance, I went to an office supply store recently and purchased a green ruler, fabricated by a company which boasts they have made rulers since 1872. You can see that the designation is cm this time, but the origin of the scale is on the end which is rounded and used to hang the ruler on a wall. The inch side gets the square end which is psychologically more appealing. You don’t think this is a big deal? When you pick up a slice of pizza, how often do you begin eating the wide, crusted end?—rather than starting with the point? Simple ergonomics matter.

A ruler that acknowledges both cm and mm units are on it

But in reality, both millimeters and centimeters exist on this ruler. To my surprise, the store brand rulers have both mm and cm designated at the end. Someone actually thought about this and marked both! Unfortunately, it now gives one two possibilities for what the numerical marks might designate, instead of resolving the situation. Assuming one knows which are cm and mm,  a person can, for example, measure something with an American “Metric” Ruler, which is say 1.5 cm long. So how is this done? One first looks at the 1 cm designation, then counts the millimeters, and concatenates them with a decimal point to obtain the answer. You are always holding the first digit in your mind 1 and then counting to the next digit, which is 5 and then creating the answer of 1.5 cm. This is true even if you designate the millimeter graduations as tenths of centimeters. When I first received an Australian metric ruler, it had nothing but millimeters, and my mind quickly responded to its ease of use. The Australian who sent it to me said “I learned early on that centimeters cause mistakes, and in my business this cost me money, and I stopped using them.” He told me it took Australians a while to realize this, but more and more, he was seeing centimeters, less and less.

Custom metric rulers given to Metric Maven Clients

In my engineering work, I have never seen a metric drawing in centimeters. After I had used a metric ruler marked only in millimeters, I hoped I would never encounter one. A client who is an imperial die-hard informed me that there is no use using metric, you have to buy meat in pounds, and lengths in yards, or feet or inches in this country. I was told to “get real.” My reaction to his statement was not what I expected, my mind wandered back to my youth, when lumber yards, car dealers and others would hand out free yardsticks on the Fourth of July, Labor Day and on other important dates for advertising. I realized that I needed to hand out mm only rulers  to my clients, as I suspected many of my clients, despite all being engineering firms, had never seen such a thing as a mm ruler. I first tried to get wooden millimeter rulers from wooden yardstick suppliers. One of the vendors informed me, in no uncertain terms, that this is America and we use inches. Finally I came across a supplier who would make custom metal mm-only rulers for me. I decided to go with a 600 mm long ruler to hand out to my clients and their Engineers. I reasoned 600 mm would be long enough to measure most common designs found in my industry, which is microwave and antennas. The rulers are metric-only (no inches), have my company logo, name and information, just like the old wooden ones, which are now collected as antiques. The end of one of my mm-only metric rulers is shown in the inset above.

When I handed out the mm-only rulers, I was pleasantly surprised by the reactions. One Engineer said “Oh, thank heaven’s it’s 600 mm, that’s actually a useful length.”  Two others at another company took the opportunity to thank me for suggesting the centimeter be eschewed, they really found it simplified matters. One older Engineer said “It’s amazing, I’m starting to lose my feel for inches, and think in millimeters now. This ruler is great.” I was floored. I was used to a much more visceral and negative reaction, or one of dismissive semi-contempt. I later had lunch with two Engineers, one of which has seemed to enjoy his attempts at devil’s advocate for centimeters. He continued trying to needle me, and then quickly moved the ruler I’d given him closer to his person, and said “Now you aren’t thinking of taking this back—are you?” I replied “I can see that a ruler like this desperately needs to be with someone like you.” When I took a ruler to the Engineer who had told me to “get real,” his countenance was that of a person who had asked me to find a Unicorn, and I had obtained one, broke and saddled it for his riding pleasure, then delivered it to his door.

This is the first time, that I felt I might have made a small difference in American metrication, but why was this time different? My conclusion is the ubiquitous presence of American “Metric” Rulers. They offer very little obvious advantage, and probably are viewed as an equivalent to decimalized inches, or are seen as even more complicated with their mixture of cm and mm scales. I’ve come to believe more and more that American “Metric” Rulers are a big obstacle to Americans adopting metric for common everyday use. With millimeters, one almost never needs a decimal point for common measurements, but this simplicity is never experienced, or realized, because all that is around us are American “Metric” Rulers. A small step which might help metrication in this country, would be to mandate that ruler manufacturers change the “metric” side of our dual-scale rulers to millimeter only. It’s a minute change, but I think it might cause people to view the metric system more favorably, and even possibly use that side of the ruler more often. Dual scales (mm and inches) clearly violate Naughtin’s Laws, and conspire to put off metric use, but it would be some small victory toward mandatory metrication.

I have wondered many times since, that if, many years ago, I had attended local Fairs in the Midwest, where the metric side of the wooden yardsticks was in millimeters,  if we might not be much further down the path to metrication, and not continuing to stand still as we have been for over 150 years.

Related essays:

Stickin’ it to Yardsticks

The Design of Everyday Rulers

America’s Fractional Mind

If you liked this essay and wish to support the work of The Metric Maven, please visit his Patreon Page and contribute. Also purchase his books about the metric system:

The first book is titled: Our Crumbling Invisible Infrastructure. It is a succinct set of essays  that explain why the absence of the metric system in the US is detrimental to our personal heath and our economy. These essays are separately available for free on my website,  but the book has them all in one place in print. The book may be purchased from Amazon here.


The second book is titled The Dimensions of the Cosmos. It takes the metric prefixes from yotta to Yocto and uses each metric prefix to describe a metric world. The book has a considerable number of color images to compliment the prose. It has been receiving good reviews. I think would be a great reference for US science teachers. It has a considerable number of scientific factoids and anecdotes that I believe would be of considerable educational use. It is available from Amazon here.


The third book is not of direct importance to metric education. It is called Death By A Thousand Cuts, A Secret History of the Metric System in The United States. This monograph explains how we have been unable to legally deal with weights and measures in the United States from George Washington, to our current day. This book is also available on Amazon here.