Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Will the US ever go metric?

  1. Jun 27, 2012 #1
    Officially, the US adopted metric units as the legal standard in 1866, but never seriously attempted to implement a plan to phase out "customary" units. As a result, the US is the only industrialized nation which still uses non-metric units widely in commerce and law.


    A while back a British member posted opinions about this and was met with a tongue-in-cheek defense of inches (2.54 cm), ounces and pints. I joined in, pointing out that if we used a base 2 rather than base 10, one mile is close to [itex]2^{16}[/itex] inches (63360/65536 or 0.966796875 mile). There have been a number of initiatives to "go metric" in the past which have gone nowhere.

    Can the the US continue to use non-metric units indefinitely as long as it can manufacture to metric specifications (for export purposes) and use metric units in scientific and at least some engineering applications?
  2. jcsd
  3. Jun 27, 2012 #2


    Staff: Mentor

    Look how much pain was inflicted when we switched daylight saving time recently. Older devices which had the switch down cold failed.

    Imagine the confusion of removing non-metric completely. While its true many things you buy today have dual units of measure, there's always that favorite poem, song, recipe or old set of plans or even collection of nuts and bolts that someone has and its not in metric.

    I think the only way is that the old units will simply fade away after time, maybe by removing them from items sold and then removing non-metric tools...
  4. Jun 27, 2012 #3
    A casual glance at history suggests that changes in units of measure are not fully adopted except under heavy handed dictatorships.

    I've recently seen a few authors drifting back to B.C. and A.D. which is good since the PC pressure for correction was based on a genetic logical fallacy:

  5. Jun 27, 2012 #4


    User Avatar
    Gold Member

    I do a lot of my own mechanic-work/repairs, so I have to own full sets of standard and metric tools. I don't own a Harley anymore, but there is still a lot of non-metric machinery around here. It would be expensive to do a "hard" conversion, IMO, so there is resistance to a wholesale change.

    Just changing the speed-limit signs, road signs (XXmiles to xyz), etc, would cost a lot of money that our state can ill-afford to spend. I'm not anti-metric by any means, but it's a good idea to weigh the costs of a hard conversion. A good friend of mine does mechanic work on our vehicles that I am not skilled enough to do, or that requires heavy air-tools, a lift, etc. He has to have full sets of metric and standard tools, from teeny-tiny point wrenches to huge sockets and everything in between. He has a small one-man, one-bay garage, and it must have pinched his finances to buy full sets of every wrench you can imagine.
  6. Jun 27, 2012 #5
    We should be slowly moving toward metric, but it seems like we're moving away from it. I used to see speed limit signs here in the US that had kilometers per hour under the miles per hour. I don't see those anymore.
  7. Jun 27, 2012 #6
    Agreed there has been some progress since 1975 when Congress passed a metrification act, but made it voluntary. Other countries have made the conversion in the last 50 years or so including Canada, Mexico and the UK. Right now, the US is in year 37 of the supposed conversion effort, and except for putting metric units (in addition to the non metric units) on canned and packaged items in stores, I don't see much progress. Liters have replaced quarts on soft drinks and other beverages (because they are often exported or imported) and cubic inches for displacible cylinder volume in internal combustion engines, probably for the same reason. But that's not much to show for 37 years.
    Last edited: Jun 27, 2012
  8. Jun 27, 2012 #7
    Good question. The imperial system sucks. I just recently moved here and I can already say that I'll never get used to the imperial system.

    And while we're at it. Stop calling digital time "military time".

    That's why it should be phased out. Start with adding km to any new road signs, any road signs that are replaced etc. In a 100 or so years it would be fully metric.
  9. Jun 27, 2012 #8


    User Avatar
    Science Advisor
    Homework Helper

    Well, I guess I must be living in a heavy handed dictatorship in the UK. In my lifetime pretty much everything has moved from "imperial" to metric units. There's nothing much left in imperial except road signs and speed limits, using miles not km. Oh, and pints of beer. But that's about it.

    We even managed to change the currency from pounds shillings and pence to decimal without having a revolution.

    There is clearly a large one-off cost to convert the road signage, and room for confusion beteen old 50 mph speed limits and 30 mph limits converted to 50 kph if it was done in stages, but I assume it will happen eventually.
  10. Jun 27, 2012 #9
    Well, you're right, "heavy handed dictatorship" is hyperbole. I should have said people don't change measuring systems unless the government enforces the change.
  11. Jun 27, 2012 #10
    I sure hope so. But then someone has to invent the 19.05mm socket, less we go unable to repair older automobiles.
  12. Jun 27, 2012 #11
    It likely will never happen. Even Canada uses a lots of non-metric stuff (civil).
  13. Jun 27, 2012 #12


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    I'd like to think that we're making progress. After all, every chemistry, physics, biology, and engineering student for the last 30 years is completely comfortable with metric. I'm confident in saying that most prefer it.

    But a total change over...that will be a while.
  14. Jun 27, 2012 #13
    It's interesting that Canada did replace its road signs but has still not made a comprehensive conversion. My experience as a visitor was that it was fairly comprehensive. I remember buying deli items by the 100mg (hectogram?). It would seem highway speed limits would be the most dangerous to convert. I've driven the 401 between the US border and Toronto a number of times and there were sections where the drivers (both Canadian and US plates) seem to think 100 meant 100 mph.
  15. Jun 27, 2012 #14
    I was referring to engineering services. I am working in a government utility corporation. It is heavily non-metric. But yes, road signs and speeds are in metric.
  16. Jun 27, 2012 #15


    User Avatar
    Science Advisor
    Homework Helper

    but a lot of food in the uk is still sold in jars or cans of 454 grams

    which just happens to be a pound! :rolleyes:

    so we're all set to return to imperial … just as soon as the usa rejoins the empire, and starts driving on the left! o:)
  17. Jun 27, 2012 #16
    It will be many fortnights before that happens.
  18. Jun 27, 2012 #17
    I still have machines with whitworth fasteners. So I have 3 sets of tools. Wrenches, taps, dies, etc. the BSW / BSF stuff is hard to come by in the US now. The bolts and nuts have to be made by hand or purchased at astounding prices. Can't get those at the local TrueValue hardware store!
  19. Jun 27, 2012 #18

    Ivan Seeking

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Yes, for everything except missions to Mars.

    There are so many units of measure that are unique to a particular field that metric vs standard is only a small part of the picture. For example, frequency can mean per second, per minute, or even per hour or year, depending on the subject. If you don't know the subject, you may not know which frequency they mean. At least with general measures of length or distance, mass or weight, temp, torque, force, speed... the units of measure are generally specified, and usually for both standard and metric. I have to jump back and forth constantly and hardly even notice anymore.
  20. Jun 27, 2012 #19


    User Avatar
    Homework Helper

    When I drove a rental car in the US, I was thankful I was able to mentally multiply by 1.6 and 5/8 fairly quickly. :tongue:
  21. Jun 28, 2012 #20
    I'm a mechanical design engineer. I've worked for many companies, designing everything from wood chippers to jet engines. In all cases the default has been to design in inches unless the customer wanted metric. About 20% want metric, but most of those really want the design in inches, but show all the inches converted to mm on the drawing. Only our European customers want full metric. All the US government work is required to be in metric, but the first thing that happens in any new government program is that the civil servants get a waiver to design in inches.

    Inches are a whole lot cheaper in the US because everything is designed around them, and the workforce is conditioned to think and work in them--the automotive industry not withstanding, since they seem to have done well with metric.

    So I'd say that inches are here to stay.

    I'm equally comfortable with both systems, and don't really care which system someone wants to use. They are both equally good. If anyone has a preference for one over the other then that just indicates that person understands one better than the other.
    Last edited: Jun 28, 2012
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook