US Electronics: A Metric Peg in an Imperial Hole

By The Metric Maven

Bulldog Edition

The Metric Maven has read countless articles about the decline of American electronics manufacturing. Pundit after Pundit who almost certainly have no idea which end of a soldering iron to pick-up, feign deep knowlege of what makes us “uncompetitive.”  There is always a laundry list of problems which are trotted out by these professional opinion manufacturers. The one item which is never on their list, is the lack of the metric system in the US. This omission is proof by proxy they are armchair commentators who know a thousand ways to make love to a woman, but have never had a girlfriend.

Central to the miniaturization of electronics in the 21st century is the surface mount device (SMD). They are packed into smaller and smaller sized printed circuit boards. This makes “smart” phones, and other devices smaller, and much easier to lose–I mean use. The world standards groups met long ago and defined SMDs in terms of metric. Industry PCB consultant Tom Hasherr sees it this way:

The United States is now the only industrialized country in the world that does not use the metric system as its predominant system of measurement.

All the World Standard Groups involved in the electronics industry (IPC, IEC, NIST, JEDEC, EIA & JEITA) have made the transition to the metric measurement system. They formed an alliance to stop using English units and all the data they publish is in metric units.

Buried within these diplomatic statements is a larger story of America looking down, taking direct aim, and shooting itself in the foot—with inches.

The story goes like this: Once upon a time in the 1980s the world standards organizations banded together and produced worldwide metric standards. The Electronics Industries Alliance (EIA) in the US was given the responsibility to articulate the size of surface mount devices. The world had created all the standards in metric, and the EIA was to publish the new dimensions for all to use. A book was printed with all the component names, dimensions and other pertinent engineering data. It was then released to US manufacturers for implementation.

American component manufacturers refused to make components to metric dimensions. The PCB assembly and etching houses rejected metric dimensioned drawings, and spurned any thought of using them. They repeatedly demanded the EIA publish a version of the standard with Imperial (English) units. The EIA finally did this and unilaterally changed the names of the components.

The metric SMD components were now renamed using inches. Originally, the first two numbers of the chip component names are the SMD length in mm, and the second two are the width in mm. There is an assumed decimal point between each set of paired numbers. For example 3216 is 3.2 mm x 1.6 mm. Here is a short list of the renaming:

Now the 3216 is renamed 1206 which is 0.12″ x 0.06″ with an assumed decimal point at the front, and whatever conversion factor error is introduced. We can see that this US “improvement” introduced the same name designation for different sized electronic SMD components. After this re-naming, should you be interested in an 0402 or 0603 device, one now has the opportunity for a metric/imperial nomenclature mistake, which could precipitate lost time and money.

When the world standards committees discovered what the EIA had done, they released an order for the EIA to cease publication of this non-metric document. The EIA was reminded they were in violation of the international agreement they signed with all the world standards bodies agreeing NEVER to publish ANY standards using Imperial (English) units. In 1991 the EIA stopped publishing the feral document, and it is my understanding, that because of this, there is no longer any official standard  followed in the US.

The US component manufacturers and PCB etching houses returned to the days of the perch, furlong, and barleycorn. With no standard to follow, SMD manufacturers began to game the situation. There were no longer standards for capacitors or inductors, or common three leg transistors known as SOT23.  So 20 different sizes of these small outline transistors (SOT23) appeared. Chaos ensued. Rather than impose order by standards regulation, or metric adoption, the US industry just tried to figure out a way to name the multitude of these ad hoc non-interchangable “standard” parts.

The rest of the world embraced metric measurements and metric standard electronic parts. If you are in Germany and order parts from Japan, or Korea, or Timbuktu, you know they will fit on your printed circuit board. These are all metric countries.  You have no guarantee if you order American electronic surface mount parts, that they will fit. If you were a German, would you take the chance?

The situation is actually far worse than I have explained thus far. In the United States our PCB software puts down grids in mils (a feral unit of the inch) or in inches. The world standard for parts is metric. The standard grid size for which these parts are designed is 0.05mm, so there is no reason to expect the metric parts to fit nicely on an inch based software grid. They are two different measurement units! The software used to connect up parts makes many mistakes in a mixed imperial/metric environment. We often have to fix these “by hand.” There is no guarantee of compliance to layout standards when metric and imperial are mixed. Metaphorically, we are trying to fit square pegs into a set of round holes. Metric parts on a metric grid are interconnected by software to international standards.

Vacuum Tube Schematic

Over the last decade, I’ve watched as one small US based printed circuit board house after another have gone out of business. The company where I last had full-time employment, picked up and moved to China. How much of this PCB work might have remained in the US if we had embraced the metric system years ago? It’s hard to say, but it should be clear that metric conversion is of paramount importance—period. Unfortunately, the idea of industrial policy disappeared as a government concept in 1980, along with metric conversion, and has not been contemplated since.

When construction, medical, electronics and other industries are all taken together, one has to wonder just how much it has cost us not to have mandated the metric system in the United States. There were legislative efforts to make metric the official measurement system of the US in 1866, 1902, 1921, and 1975, and they were all either rejected by Congress, or were voluntary and therefore impotent.  We may never know how much it has cost the country, because the US may never become metric.

The technically ignorant pundits who populate our media space, will continue to point to reasons that are divorced from any understanding of Engineering, technology, manufacturing, or the metric system as a problem with US manufacturing “competitiveness,” and the rest of the world will  continue to reap the benefits of their choice to become metric—decades ago.

Related essay:

The Cuprous Proxy


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.

Isaac Asimov — Technophobe

By The Metric Maven

I’ve read a lot of comments below articles on US metric conversion. Persons from outside the US often post a variant of this question: “Why on earth won’t Americans switch to the metric system?—it’s so much easier—why do you resist—what’s wrong with you?” It is an exasperated plea of confusion, which sometimes morphs into a visceral anger almost equal to that displayed by Americans confronted with the possibility of an actual metric conversion. I’ve been on the receiving end of this primal anger at the suggestion we change to metric. It is not pretty.

Isaac Asimov

It appears that Isaac Asimov (1920-1992) has described the roots of this reaction in a cogent manner in his essay “Technophobia.” The Good Doctor had used a typewriter for almost 40 years. His fellow writers had purchased and begun using word processors (i.e. computers) for their compositions. Isaac heard all the praise for the new device from other writers, but stubbornly refused to investigate these devices. “I preferred to pretend they did not exist and typed away stubbornly.”

His editor asked Dr. Asimov to write about his experiences of changing from a typewriter to a word processor. Isaac had to admit that he did not own one. The editor saw this as a great opportunity. He purchased a word processor and had it delivered to Isaac. The Word Processor would be set-up, and Asimov would write about his transition to the new technology.

The man who taught me how chemical catalysts work, what Olber’s Paradox means, what a factorial is, what relativity theory means, and countless other scientific concepts, was paralyzed with fear—by a word processor? How could this be? Technical support people spent hours with Asimov, who admits he wanted to quit several times over. The Good Doctor eventually did learn how to use the word processor, and was pleased how it
improved his writing experience. “But why I ask myself, was I so resistant to something that was sure to help me (and does) and that did not even cost me anything to begin with?” There had been many changes in typewriters over the years, but none of these caused him any monumental angst. He also realized upon reflection that:

Human beings learn how to handle numerous complicated devices in their lifetimes. The learning is not always easy, but once the complications are learned — if they are learned properly — it all  becomes automatic. The thought of abandoning it and learning something else, of going through the process  again, is terribly frightening.

For instance, the system of common measures in the United States—inches, feet, yards, miles, or ounces and pounds, or pints, quarts and gallons–is an incredibly complicated and nonsensical farrago of units. The rest of the civilized world uses the metric system, which in comparison is simplicity itself. Using the metric system would save us endless hours of educating our youngsters and be beneficial to our entire industrial infrastructure…..

And yet there is no question that the American public fears the metric system and, if it has its will, it would cling to the present system forever. Nor is it because the public uses the common units with any great skill. Very few Americans are completely at ease with them, and know, offhand, how many pecks there are in a bushel, or how many square feet in an acre, or, for that matter how many inches are in a mile. Yet we won’t change it for a system any child can learn in a day and remember for a lifetime. We invent reasons for resisting the change, but the real  reason is that we dread the process of re-learning.

It is my feeling that re-education must be recognized for the highly difficult and (even more so) embarrassing process it is.”

So why would it be embarrassing? Isaac offers no explanation.  From my viewpoint, I suspect it is because we feel we are reduced to an almost pre-educated state, like a small child. Do you remember when you were so young that you had to ask one of your parents what time it was?—because you could not read a clock.  It made you feel powerless. If you were  informed, as an adult, that new clocks were to be introduced everywhere, in place of the old, and that you had no idea how to read them, your response could easily be fear of returning to that helpless juvenile state. The reaction would probably be emotional and not intellectual. One of the first skills one learns as a child is measurement. It is understandable that the suggestion of learning a new system would be met with every intellectual excuse in your arsenal—as to why you should not.

The metric system is easier, but without learning and using it exclusively for a period of time, you have only your current experience with which to judge its utility. The 95% of the world that uses the metric system sees the situation from the other end of the telescope. They gesticulate with exasperation that you don’t see the irrational complication of the imperial grab-bag of units and methods.

I can only think of one way an American might be able to see through the other end of the metric telescope—and see how the rest of the world views us.. That is by using money as an example. We early on embraced the “metric system of money” called decimal currency. The United States was the first. We take for granted that there are 100 cents in a dollar. Do we use any other units?–of course not, no matter what the amount of money involved.  Suppose we have say $3,466 .56 in a bank account, we see dollars and cents, and nothing else. Have you ever stopped and said to yourself, “that’s just not enough units to describe money, I need more!, I feel constrained!” Never.

Farthing and Half Penny

Suppose next you wanted to make money by importing items from Great Britain, and they had stubbornly never embraced decimal “metric” currency. You would have to figure out the price of the item and then convert it to dollars. First you would have to understand that the basic unit of money was the pound, which is 20 shillings. Each shilling is 12 pennys pence.  Each penny could be divided into two half pennies, or four farthings. Now two half pence equal a penny, and six pence equal a “tanner”, 2 shillings and 6 pence equal one half crown.  A crown is 5 shillings of course.

Now that you have mastered the values of money below 1 pound, you are ready to learn that 1 guinea is one pound and one shilling or 21 shillings. So 1/3 of a guinea is seven shillings. Believe it or not, there are more values of British currency you could learn. But I think I’ve made my point.

It is easy to see how an American, looking at this situation, and wanting to do trade with a British business, would feel the urge to demand to know why on earth the British don’t use “metric” currency. It’s so much easier. An American could well react exactly the way 95% of the world population does when confronted with gallons, pints, quarts, ounces (mass) and ounces (fluid), inches, feet, miles, chains (yes we use chains to build roads), grains, and other assorted, and un-needed measurement units. The exasperation an American could feel, at the British refusal to adopt the obvious improvement of decimal currency, could easily cause them blow their top and ask: “What’s wrong with you British!–Why won’t you change!–are you fools!”

The rest of the world learned the simple metric system as children, and react with shock and horror at the complicated way we choose to measure our world in the United States. It makes no sense to them, and it shouldn’t make sense to us either.

Updated 2012-08-12

Related essay:  Longhairs


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.