Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here





What has to be done to get the US to go METRIC?


We have gone metric (officially, according to the US government).  



We are getting there, but slowly. My guess...10-20 years after old school are gone.


I'll still be looking for my gallon of milk every week.

We are in the process (past 2 years) of using metric hardware on new products, though we still design imperical.  For example, a customer needs a component that is min 1800mm long, we'll design to 70.875" [1800.2].  

One of the biggest hurdles we have is the cost associated with replacing "tried and true" commercial components with metric equals.  Many times, it's hard to find suitable replacements that are simple drop-ins.

Ray Reynolds
"Computers in the future may weigh no more than 1.5 tons."
Popular Mechanics, forecasting the relentless march of science, 1949
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?


btureblood(mechanical)and others!
My question is still not answered.


I hate it when it is mixed up. Gallons, pints, litres, metric ton...etc. My truck will tell me the temp outside in F, but the engine temp in C. Confusing.....


What will it take?

Start teaching metric only in elementary school.  

Any project using Federal funds must be metric only.


MadMango, which kind og gallon? The 4 litre short-changed version of the US, or the 4.5 litre full size version of the UK?

Life is non-linear...



It will take so many things that it will be a long time (probably greater than 20 years) for it to happen.  Here is a list of some things:

1) All divisions of the US government MUST use the SI exclusively in laws, specifications, and drawings.  It must not allow any other system(s) to be used concurrently.

2) All road signs will need to be changed to kilometers.

3) All television, radio, and outdoor signs must report the weather in SI.

4) All automobiles will need their instrument clusters to read in SI.

5) Businesses will need to recognize the advantages of converting to SI.

Number 1 is practically impossible.  Numbers 2-4 are easy to do, and would be very influential on the population since these are areas that they see every day.  Number 5 is a time issue - the SI has not been taught at universities long enough to supplant the practices at many companies.  I am embarrassed that global, high-technology companies in aerospace like Boeing and LockheedMartin use inch-pound units exclusively.  If these companies would wake up, then there would be a HUGE trickle-down effect on US businesses.



Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.



I agree with you, but it I would not blame so much the contractors on the choice of units. Please check out this Performance Specification recently issued by the US Army for a future vehicle system: FTTS Maneuver Sustainment Vehicle (MSV) with Companion Trailer. Units are liberally mixed and there are data sheets that must be transmitted back to the Government in the units detailed in the specification. Madness! I work in SI units and convert back to the requested units.

It seems to me that many Government agencies are violating the Metric Conversion Act of 1975. This act was intended to guide the use of SI units in the US.

Best regards,

Matthew Ian Loew
"Organizations cannot make a genius out of an incompetent. On the other hand, disorganization can scarcely fail to result in efficiency." -- Dwight D. Eisenhower

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.


You are right Sailoday28 - noone has answered your question, and I suspect noone will be able to until others, like UK, lead the way.  I used to point out that we started metrication in 1963, but my kids still talk in Imperial units (not "Imperical" Mr. Mungo) because we are just not committed to it.  I berate everybody I talk to for speaking the dead language of the "Metric Martyrs" (UK nonsense about weights and measures in the HIgh Street), with the result that I have no friends and have not changed a single individual's habits.

I discovered a web-site that put me right about the dates, though.  Ace-place, and one I commend to anybody with an interest in the subject.
In respect of the forum we are addressing, I would suggest that "interest" is interpretted in the classic manner and therefore embraces the entire population of the planet - its just that 99.999% of them haven't noticed.

One last thought - New Zealand is supposed by popular opinion to be a funny little back-water that is more English than England.  Is it, doughnuts!  They decided to metricate and they have done it.  No messing, no nonsense.  About 10 years I believe from the standing start, though better informed people may care to correct me.


If I haven't left it better than I found it, I haven't tried hard enough.


If you read the act, Section 3 provides two outs:


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

Note the word "preferred,"  metrification is not mandatory.


except to the extent that such use is impractical or is likely to cause significant inefficiencies

This allows the Government to claim that conversion from legacy systems would cost more, therefore, you can get performance requirements such as:


(e)Display range in nautical miles, statute miles, meters, yards, and/or feet;
  This is from a draft specification for a forthcoming procurement.



   Speaking of metric, how many countries actually use SI units?  A lot of metric countries use the old cgs system of centimeters, grams and seconds.  SI is mks, meters, kilograms and seconds.  This leads to all sorts of fun unit conversions.

   If the Americans convert to SI, how will they go about making everyone else convert to it?




Since when are centimeters not part of the SI? centi- is a prefix, meter is a base unit, there ya go.

That's one of many parts of the problem with implementation--people here in the US really don't know how to use it. They don't understand that there are plenty of prefixes to be used, and so they wind up using mm where they should be using cm and the numbers just look ridiculous.

By the way, they tried mandating metric-only federally funded highway projects, and several years later gave up. Many state highway departments revised their specs to metric only to revise them back again. The guys I talked to in the girder shops about this actually liked the metric jobs because they didn't have to do weird calculations like adding 32'9-11/16" to 16'11-3/4". (I *hate* US Customary units.)



I think that US companies are more metric than most people think.  Caterpillar, for instance, have gone metric in all their factories. US as well as European. There is one little component that they haven't been able to convert: a starter motor, where the manufacturer still uses imperial units - mostly inches and mils. According to a company spokesman, this will be changed within short.

There are probably many more examples and I think that metric units will prevail in industry quite soon. But I also think that people will use gallons, feet and pounds for a long time.


Along with NZ, Australia is pretty much fully converted and has been for 20+ years.

Road signs changed about 1973 without miles displayed at all. Measuring tapes and rules calibrated in feet and inches or even with dual calibration were actually a prohibited import for about 10 years. All government contracts demanded metric fasteners. Materials such as steel bars had "hard" or "soft" conversion, ie 4" x 2" channel section stayed the same but became 102 x 51 mm channel in the soft conversion, and eventually the full hard conversion was made to 100 x 50 mm. Metric measures in packaging became mandatory.

Following another thread on this site, we stopped buying gas in therms and now buy it in megajoules

There are still pockets of imperial measurement. Most people don't know how tall they are in cm.

It really takes a government with the will to enforce the change with no half hearted compromises, and about 20 years for all the old die hards to die.

And yes, we do use almost exclusively SI units.




The only counties that use the imperial system are the US, Liberia (in western Africa) and Burma (in south-east Asia).  The rest of the world uses metric.

(Source: http://www.metric4us.com/)


At least officially...

It appears that UK shopkeepers have to advertise in kilograms. So I've seen prices like 1.99 GBP per 0.454 kg.... exactly: 1 lbs.

Still doesn't really simplify things.


During the 1990's the Federal Government required all states to convert to the metric system for highway design and construction.  The various state DOT's responded by training their employees, rewriting spec books, converting standard drawings, rewriting software, replacing or converting survey equipment and testing machines.  Millions of dollars were spent.  Most states were producing the majority of their plans in metric when congress passed a new highway bill that did not include the metric requirement.  Almost all states have now returned to the old units.  

After some inital resistance, most of the engineers and techs I know had learned the metric system and liked it.  The push to return to imperial units came mostly from contractors.  If the conversion process had continued for a few more years I think the contractors would have learned to like metric as well.

What has to be done to get the US to go METRIC?  Our government will not make it happen.  SI will creep in slowly.    


Quote (Isntbard):

SI will creep in slowly.
It is, it is.  You don't buy your Coke or Pepsi by the gallon here, do you?

I'm working on a new engineering database, and the powers-that-be have declared all units will be SI units.  Of course, it helps that the software allows easy soft conversions; and that the company is really international.

Now quick [no ruler in view]- measure out a mm, a cm and a meter!  Those in the US - do you have it as well in your brain as an inch, a foot and a yard?


I think you all missed one point.

North America cannot go fully metric until all of industry has converted completely.  I live in a "metric" country but
My equipment that I design stuff for is made in Imperial.  
My lathes are in Imperial.
My milling machines are in Imperial.
My welding wire feeders are in Imperial.

Until someone is going to subsidize the replacement of this equipment I will need to work at least some of the time in Imperial.  I am sure that I do not work in the only company that faces this issue.  Given we replace a piece of equipment about every 1.5 years it should be about 50 years before I can commit completely to the metric system.


mm, cm, m in my head?  Yes.  In fact I usually don't do arithmetic in my head to convert from one system to the other--I imagine the physical distance, and then think about how long that distance is in the other system.

Then again, I probably don't count--I learned the metric system before I learned the English system (25 years ago) and had a terrible time changing over.  Tales of silly conversion tricks withheld till further topic drift.



Along the same lines as CanEngJohn, I live in Canada but still work with a mixture of Imperial and SI.  For example, I recently worked on an expansion to an existing oil refinery which was originally built in the 1970s (using the Imperial system).  Even though all of our design codes and calculations are now use the SI system, we must show Imperial units on the design drawings because that's the only way to match the new structures, equipment, etc., to the existing facilities.

When I was in university, one of my professors told us that if we're going to practice engineering in North America we'd better learn both systems, becuase NA will never be entirely Imperial or SI.



As pointed out here, using metric isn't a problem; converting to metric is the problem. Like CanEngJohn says, unless you can afford to convert everything you have over to metric all at once, there will always be difficulty in having some stuff still in Imperial and some stuff in metric.
I worked in Virginia for six years, and one of the counties in which we did work decided to go all metric, so the civil engineering plans we drew up for submission were all done in metric.  The whole thing fell apart after about a year, because construction manufacturers were not providing building materials (storm drainage or sewage pipe, for example) in metric, nor had they developed conversion pieces.  They came to realize, too, that if they had metric materials available, trying to tie it into existing Imperial systems out in the field was just plain impractical and inefficient.  So they went back to Imperial units.  It's got to be all or nothing to work.

As a CAD drafter, I was happy about going back to Imperial because of labeling on the plans.  Whoever prepares the plans is always trying to put 10 pounds of information into a 5-pound plan, so to speak, and metric information takes more space.  As an example, the text [48"] takes up a whole lot less space on a plan than [1016mm] does.  We also had to label things in both metric and Imperial units, which really took up valuable space and cluttered the plans further.  The county didn't modify their Imperial codes to sensible metric equivalents, either, so their earlier easement width requirement being, say, 25 feet was not rounded to a nice, even 8 meters (as opposed to a direct conversion of 7.62 meters).  Stuff like this just was just plain poorly conceived.

Maine put kilometers as well as mileage onto their highway signs, but missed the whole point of metric on at least one sign on the Maine Turnpike, which advertises Exit 6A as being 3-1/3 km ahead.  That one had me in hysterics.


Right, like the US EPA using g/mile as a measure of pollution emission in cars. They got it half right (the g part).

Best regards,

Matthew Ian Loew

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.


When South Africa was going metric all the imperial maesuring devices were banned. It is impossible to buy imperial tape measure there today. But is this a solution for USA?....doubtful...

Putting Human Factor Back in Engineering...

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close