‘Think metric’. A customary way to success

We look at the metric changeover in the UK construction industry, and some of the posters that were part of it.

The comments that followed our last article included variations on the word “convert” about 25 times, including eight in upper case. There are, of course, occasions when it is necessary to convert, but it is best avoided. So this week, Metric Views takes a look at the metric changeover in the UK construction industry between 1967 and 1975, and the accompanying poster campaign run by the Construction Industry Training Board (CITB) on the theme, “Think metric”.

Imperial measures were less than ideal for construction. Setting out was done in feet, inches and eighths, with risks of error during addition and subtraction. Levelling however was done in feet and hundredths. Excavations were measured in feet and inches, but volumes were calculated in cubic yards, without calculators. Laboratory work may have been done in metric, but design calculations were in Imperial. Readers who worked in construction during the 1960s can probably add to this list.

So in 1965, when the UK Government said that they “consider it desirable that British industries on a broadening front should adopt metric units”, there was widespread agreement in the construction industry that it should aim to be at the head of the queue.

Preparation was thorough. Standards, design codes, publications, university and college courses, qualifications, training, publicity, product development, modular co-ordination, the supply chain, and so on – all received consideration. An agreed timetable was published in 1967.

Clearly the workforce would play a key part in the success of the changeover, and the CITB was commissioned to devise a poster campaign with twin themes: ‘Think metric’, and ‘Use millimetres’.

The importance of ‘thinking metric’ during a changeover from older measures had long been recognised, but an emphasis on millimetres was unusual. However, the construction industry had concluded at an early stage that the use of the centimetre should be avoided. Among the reasons was the fact that using the centimetre risked error from misplacing or omitting the decimal point, with 1/8 inch and 1/100 foot both being about 3 mm. The CITB also foresaw that anyone unfamiliar with the metric system might see the centimetre as the metric version of the inch, and would tend to use it unless encouraged otherwise.

Our first two posters show both of the campaign themes. The five postage stamps in the left hand poster are each dimensioned “20 mm”.









Our third poster would perhaps be controversial today – it shows how attitudes have changed over the past 45 years, and clearly belongs to a bygone era. But it also underlines the ‘Use mm’ theme. Even today, the general public might expect to see centimetres if such statistics appeared in metric measures.


In 1961, the Meteorological Office switched internally from Fahrenheit to Celsius, and in 1962 started issuing public forecasts in dual units. But, although science had been metric since 1900s, many industrial processes still used F. So it is understandable that the CITB would wish to draw attention to a temperature scale that might be unfamiliar. It is surprising, however, that there are still people in the UK today who claim Celsius is unfamiliar!


And finally, here is a play on words that might be appreciated by someone who had spent the day working in the sun on a building site. We shall be returning to the idea of ‘Drink metric’ in a future article.


The metric changeover in the construction industry was a success, and was largely completed on programme. The benefits were quickly felt. As an example, UK consultants such as Arup and Fosters went from strength to strength in an increasingly metric world.

So here is a paradox. All new roads in the UK for the last 45 years have been designed in metric, generally for speeds of 50, 60, 70, 85, 100 and 120 km/h. But just before completion of construction, Imperial signs for distance and speed are installed. Furthermore, almost all the vehicles on UK roads today have been manufactured to metric designs, with those intended for the UK fitted, uniquely, with RH drive and an mph option on the speedo. Yet the metric is largely hidden from the driver, who could be forgiven for thinking that little has changed in this respect for 50 years.

63 thoughts on “‘Think metric’. A customary way to success”

  1. It’s too bad the producers of the poster of the woman in the bikini didn’t have the foresight to give the dimensions as a more rounded 900-600-900 in millimetres. 90-60-90 (centimetres) is well understood world-wide. If anything 914-610-914 is a major turn off when it comes to relating to those numbers.


  2. Ah, I remember well manually ‘squaring’ take-off ‘dims’ – things like 4′ 9 3/4″ x 15′ 11 1/2″ x 1′ 2 1/4″, which is how they were written back then. Pure mental hell. Metrication made that part much quicker, simpler and more accurate (along with the advent of electronic calculators of course). Standards are today purely metric, and some (e.g. the Canadian engineering standard Limit States Design for Buildings and Structures) have only ever been metric and cannot be converted nor do they have an imperial counterpart.

    Was a speed limit of 85 km/h ever considered? If so, that would be in contravention of the universal standard of increments of 10 km/h only. That is certainly what Canada did, and I believe it is mandatory in the UK today with mph.

    RHD is certainly not unique to the UK of course – about one quarter of the world’s cars are RHD, and that is actually increasing as the Indian sub-continent become ever more personally mobile. So manufacturers can spread the cost of RHD vehicles over quite a large proportion of their production. What IS unique is RHD with dual marked speedometers, odometers in miles and all the other dual or imperial information that is presented in today’s computerised vehicles. I once read that this adds about £20 to £50 to the cost of the average car – as much or more each year than the one time cost of converting our road signs, but of course well hidden in the overall cost of a car. For manufacturers who don’t sell in the USA (the only other market where imperial units are found) this is a major effort to tailor such instrumentation purely for the UK market.

    As for downing a litre? I certainly would like the option of buying a half-litre of beer when 284 mL is not enough but 568 mL is just a bit too much.


  3. @John FL,
    As much as I favor going metric, I think the cost of a unique instrument cluster is a red herring. In North America, we make (in the same plant) US and Canadian cars, with miles odo and mph-primary speedometer for the US market, and gladly make (for less than 10% of the US market) a metric version for Canada. The variable cost difference on the parts is negligible, pennies or zero. There is a setup cost for creating the extra part numbers (including design, building prototypes, testing, etc.) and some overhead in the plant to make sure the right cluster goes in the right car, but frankly we have a lot of other options (as ordered by the customer or dealer) to control and we are quite used to doing so. On a very low volume vehicle, the initial setup costs might amount to something, but on high volume cars, it is negligible.

    It would be nice to be rid of it, as every point in the assembly where the correct option of two or more possibilities must be installed is a chance for a mistake, but the customer will no longer accept a black Model-T with one engine and transmission option. Managing assembly complexity (number of unique option build-outs) is a critical part of a car manufacturer’s business model. He may rail against it, but he knows he has to manage it.

    LHD and RHD was a bigger issue for us (US side of business only). The US designers regularly exploited the asymmetry option of knowing which side the steering wheel was on, and made the cost of a RHD export model look astronomical. Fortunately, as a multinational, our European designers were used to it, and frankly, had to put on some “RHD for dummies” seminars to allow export models of US-designed cars.


  4. For those who are conscious of their alcohol intake, “downing a litre” (or at any rate half a litre) simplifies the calculation. A litre of “X”% AVC beer/cider etc contain X units of alcohol. Thus half a litre of 5.2% beer contains 2.6 units of alcohol (2.6 is half of 5.2). Simple!


  5. @John FL:

    As far as I know, all cars produced in Asia in RHD are metric only for the display. In some countries, cars that reach a certain age have to be replaced and the older models are sold in other countries (grey market). Metric weak countries like Burma and the Caribbean are flooded with these cars and it does help assure that the kilometre displaces any attempt to use miles.

    However, the UK is the only country that requires that these grey market cars when imported into the UK be de-metricated. But as you and I know there is a price to pay for this. Cars that go to the other countries don’t bother to change the display as many can’t afford the cost.

    What about Irish cars sold in Northern Ireland or England? This boils down to the citizens of the UK being forced to pay money a ransom they don’t have for something not necessary and not done elsewhere? Especially at a time of austerity and increasing poverty.

    Whatever is the cost of a onetime change in the signs is more than offset by the costs of having displays in cars that have an inherent added cost in the hundreds of millions, a cost that will never end until it is deemed no longer needed.


  6. @ John Steele:

    What would be the cost to you if you wanted to buy a second hand car from Canada and you had to pay someone to switch over the speedometer before you can get it registered?

    Such a difference does add cost, even if infinitesimal that needn’t be there. But of course the auto company doesn’t care as they just pass the cost on done to the consumer. Even a small amount hurts when much of the buying public can barely pay their bills.


  7. I was only speaking of new cars, and manufacturers building the car for initial sale. Swapping would be done by removing the whole cluster and putting in a new one, and the cost would be high. You wouldn’t get a fair credit for the one removed.

    I have no experience with bringing a used vehicle into the US and what must be done to bring it to US standards. A car that will be sold as new must fully comply with FMVSS, emissions, CAFE, etc. I think a used car imported by owner is less stringent, but I don’t know details. I do know if we brought a non-compliant car into the US for test we had to certify that it was sent back or crushed; we could not sell it here. Shipping a single car is MUCH more expensive (per car) than shipload; we usually crushed them.


  8. A good friend of mine who used to live in South Africa returned to the UK a few years ago. he brought back with him a VW Golf that was to a uniquely South African (and highly tuned) specification. But to register it in the UK he had to have the entire instrument cluster changed. It cost him over £700. Ridiculous.


  9. Half a litre is not a good idea for a beer size. Ireland and Australia use 570 ml and call it a pint, that is what Britain needs to do. The public will not accept losing ~68 ml of beer as the price won’t be reduced much at all as many people buy just 1 pint at a pub so the pub won’t be able to lower prices much. If you make it 570 ml you get ~1.8 ml extra beer, there would be little resistance from the public if we changed the definition of the pint to 570 ml.

    Editor. We shall be returning to this subject with an article to be posted on 14 August.


  10. @ Dave:

    Since all glassware sold in the UK for beer already is 570 mL, what you are referring to has already happened. At least in practice, not in the official definitions and media descriptions.


  11. The question of speedos in cars is always an interest to me and it was interesting to read that the cost in North America of installing metric or miles is negligible… but what about the pre-production cost? Much of what goes on in cars is now software based and that would be written using a base unit (and outside UK and US it’s a foregone conclusion that would be metric). What you’re then doing is writing an additional module to deal with conversion from the base unit to the secondary display, that and any associated testing incurs additional cost, something that would be completely unnecessary if just one unit were used.

    I’ve also noted (having recently replaced my own car) that there are some newer UK models that do NOT have dual speedos (at least not on the analogue speedo). I read with interest that EU rules seem to require metric and allow imperial as a primary indication provided metric is also shown however current UK regulations seem to have omitted the requirement for metric. A growing number of newer cars on our roads are not metric ready!


  12. @Alex

    I used the phrase “setup cost” but I acknowledged there were costs from drawing the drawing through testing prototypes. However english/metric is very trivial. In any case, the costs are amortized over the volume of the carline, so these setup costs could only matter to a VERY low volume manufacturer. There is also some ongoing overhead in plant to maintain a unique part number and control option buildout, putting the right part in the right car. We refer to the number of buildable options as complexity and we swear we hate it, but we create a lot of it for both legal compliance and customer preference. The truth is that we don’t hate it as much as we claim IF we figure out an easy way to do it and it sells a few more cars.

    Classical odo: change two gears (the tooth ratios have to be correct and the difference between centers constant so the teeth mesh (same shaft locations for the reduction gears to turn the little wheels), so I don’t know how to do it in one gear, and a common mechanical frame. Electronic odo: Change a divisor factor; we actually program both and a jumper (or switch) decides which the car will do. This part is typically shared between multiple car lines.

    Speedo, analog: If you paint two rings, decide which is the scale of the outer ring. The drawing showing where to put the marks is metric, whether the marks denote a mph or km/h speed. Digital speedo: change a factor; again this will always be setup for both with a jumper or customer-accessible switch deciding. The analog mechanism is usually shared across carlines, but the marked face plate is unique to carline and sometimes trim level.

    A US manufacturer is ALWAYS thinking about the Canadian market, and it is more likely a British manufacturer is thinking about the Continental market.

    As for the code, we are usually dealing with a sensor that gives a LOT of pulses per displayable unit. We have to divide to get to displayable units and the factor is large enough to easily accommodate the 1.609 344 ratio (we round off) between mi/km. We just program the two factors and a decision switch into the original modular. It is not like we ignore a secondary requirement until the very end and then worry about how to handle it. (Unless we fail to recognize it. It wasn’t that many years ago that US-designed cars simply didn’t consider a need for RHD and could not be exported to RHD markets.)


  13. @Paul Trusten:

    We’re working on it Paul! While the draft beer is perhaps not a major issue, certainly the road signs is of major importance. The problem is a combination of obstinate politicians who fear an electoral backlash and plain inertia. But other countries have done it very successfully – just needs the powers that be to learn from them.


  14. @Daniel/Alex
    There is no requirement for cars imported into the UK to be “de-metricated”. As far as I know, the only requirement with respect to units is that the speedometer must be able to show both mph and km/h, either simultaneously or switchable. There is no requirement for the odometer to be converted. On the other hand, the headlights and mirrors will have to be replaced, or adjusted where possible, to comply with UK left side driving regulations.

    These issues though would be the least of your worries if importing a car, especially if it was from outside of Europe; in which case extensive modifications may be required to comply with emissions, safety and radio frequency regulations.


  15. @Charlie P,
    Cars sold in Australia are right hand drive and comply with, probably exceed, UK regulations.They have speedometers that show only km/h (and odometers that show only km.) As far as I know MPH has been illegal on all cars sold new in Australia from about 1975. I would imagine that speedometers that are switchable in Australia are also illegal. That means they would have to be “de-metricated” if imported into the UK.


  16. @Charlie P as I mentioned in my last paragraph, current type approval rules (at least the ones I have found on-line) do NOT require any metric markings or switchability on cars sold in the UK. For instance I seem to recall seeing a recent (BMW) Mini recently with a speedo which ONLY showed MPH – and I do also remember seeing one car test drive on Top Gear last year where I re-wound because I was sure I couldn’t see any obvious km/h markings on the speedo (I do not recall what car it was).

    This, along with the continuing use of “m” to mean “miles” on new road signs could be seen as a conspiracy to make any future push to convert roads to metric harder and more expensive than it needs to be.

    It also makes many cars almost useless if driven outside of our small island. How much leeway do British police give visitors to Britain if they break the speed limit in a metric-only vehicle and what will we get in return for doing the same in an Imperial-only vehicle? I ask this with a news story yesterday from the BBC saying that police in Scotland plan to stop giving drivers the traditional “10% + 2 MPH” leeway on speeding offences.

    I will add that I am personally quite pleased with my 2010 Astra which has a digital display (alongside the regular analogue speedo) that can be switched in it’s entirety to metric. Though I can see the garage switching it back to miles every time I take it in for a service!


  17. I think that Britain is the only country that explicitly bans the use of metric speedometers So much for ‘freedom to measure’, which is always bandied about by those opposed to metric (metric is force, Imperial and UCS stand for freedom). Everywhere else motorists are just asked to observe the speed limits. If I wish, I could buy and use a car with mph on the speedometer (not that I would ever do that!)


  18. @Alex
    A dual mph / km/h speedo used to be a requirement in the Road Vehicles (Construction and Use) Regulations. I can’t imagine that they’ve amended it out.

    On some UK spec MINIs, there is a big ornamental central speedo that does have an mph only display. In such cases though there is another digital speed display in the tachometer dial seen through the steering wheel, and it is switchable.


  19. @Alex and others:

    I have just acquired a 2014 Volvo V40. It has Volvo’s digital display (no analogue). The main speedometer has a digital (numbers only) readout, in mph. However, I have switched the Units setting in the My Car menu to metric, which gives me an auxiliary km/h readout at the very bottom right of the display. I also get fuel consumption in L/100 km (while moving), or L/h while stationary (typically 0.2 to 0.3 L/h). Bizarrely, the primary odometer also now reads in km, which, while I like that (it’s what I got used to in Canada), confuses everyone else.


  20. @Hn Maenen
    Not only does the UK not ban the use of metric speedometers, the UK has actually required all new cars sold in the UK market be fitted with a km/h speedometer (alongside the normal mph one) since at least 1985.

    Conveniently though, car technology has moved on a long way since then, and car software can, not only make multi-market compliance much easier for manufacturers, but can give individual motorists in those markets the information in the units they want, rather than the units they are told to have (mpg, L/100 km, °C, °F, mph, km/h or whatever) without the need to hard-code for one system or the other. It’s a pity the RHD/LHD problem isn’t so easy to solve!

    This is also the trend with other software-centric services, such as various online services and hand-held smartphone services. Weather forecasts, for example, can allow users to mix and match units as they desire for wind speed, rainfall and snow depth, as well as for temperature. Online shoppers can be given the choice of units for buying by and for price comparisons: p per lb, £ per pt, p/g, £/dm3, or whatever.

    In fact we are moving towards the day when current hardware-based legislation concerning units will become redundant.

    Imagine speed limits, whether defined in mph or km/h – or even in the SI unit m/s – being relayed to drivers, not through a physical, environmentally unfriendly, street-cluttersome, road sign on a post, but in real-time for wherever they are on the road network, directly through their driver’s information system – in whatever units they wanted to see them in! The driver would always be able to know the precise speed limit. It would be more efficient and more economical to manage speed limits too and units wouldn’t matter.

    On the downside, UKMA (and ARM) would be redundant… Or would they? I’m sure I am about to find out why they wouldn’t… 🙂


  21. My VW Jetta has a dual MPH & km/h display to the right of the driver. In addition, the odometer switches to a digital readout of the speed in km/h when the car is in motion. Whereas the analogue speed display is partially blocked by the steering wheel, it can be ignored as the km/h display is directly in front of the driver.

    When stationary though, the odometer can also be switched to display a trip setting.

    The display looks like this:


    I wish there was a way to switch the odometer to kilometres and the temperature to degrees Celsius. If there is, it must be a secret. There is no way to select units, but I am happy I can at least know my speed in kilometres per hour. Better than nothing.

    However, a GPS device can be used to give all of the information in metric and the dash display can be covered up to hide unwanted units.


  22. Charlie P’s ideal world where devices can be used to select units creates an interesting scenario where two people come together to discuss something and can’t understand each others units even though they are speaking the same language.

    How would that work in an engineering office where one engineer is using different units than another for the same product? Would everyone require a unit translator to communicate? Of course, this would only happen in England and thankfully not the progressive nations like Germany, Japan, China etc.

    Even if you had translators to ease communications, how would they get around the round number versus non-round number issue? How many people on the street could handle increments of 25.4 mm or 0.453592 kg or vice versa? I can see where yards will just be another name for metres, but there are some units you can’t do that to.

    When products are sold in primary metric and the pricing is converted to imperial, does the price round up or down? Who takes the loss? Seems this ideal world isn’t so ideal after all. Thank God the German economy is stronger that the UK and Germany’s sense when it comes to weight and measures makes it a powerful and prosperous country, while the UK is stuck in economic austerity.


  23. @Charlie P et al…

    I agree that it seems odd that this requirement would be edited out however I seem to recall a couple of years ago looking up this particular legislation on-line after seeing a car with a MPH-only speedo and the most recent copy of the document I could find made no mention of the requirement for dual units.

    IMHO having a MPH-only analogue dial and then a digital display that can switch between the two may be to the letter of the law/EU directive but would short change the vehicle owner if we did change over at some point as sometimes this is part of a multi-function display which the driver may prefer to see a different item such as trip counter or fuel range (as with the car I just purchased).


  24. I bought a new Hyundai i20 last year, this was from their plant in Turkey, and it is fitted with a speedometer that has the primary ring in mph, with the kph bit as a secondary ring that to be blunt is almost impossible to see – in part due to its size, but also because the red colouration they gave it doesn’t really make it stand out from the background (and no, I am not RG colour blind).

    As for switching units, that would be a major headache as I simply ain’t got a clue with metric.

    Guess you could say that is due to the failure to get it over and done with 40 years ago – before I was born btw 🙂


  25. @bodrules:

    I would be highly doubtful that your vehicle has a speed display showing “kph”. I checked your model car online and couldn’t find one dashboard display showing “kph”. They all showed the correct km/h. Is yours an exception? Can you provide a photo showing “kph” on a display?


  26. @ Daniel

    Eh? You seriously don’t know that;

    mph = miles per hour

    kph = kilometres per hour



  27. @Daniel
    In normal English, both spoken and written, “kph” is a commonly accepted abbreviation used in place of kilometres per hour. “km/h” on the other hand, is nothing more than the SI symbol for it.

    You’ll often hear people saying something like: “200 kay pee aitch”, as you do “100 em pee aitch”. But I’ve never heard anyone say “200 kay em forward-slash aitch”.


  28. Bodrules says: 2015-08-12 at 12:24 @ Daniel
    Bodrules, you leave us totally bewildered here. Have you ever looked at your car speedometer?

    I am sure we are all intrigued by this one you have. All Speedometers that I have ever seen are marked: –
    MPH = miles per hour
    km/h = kilometres per hour

    The kph = American AP style guide anomaly, it is plain wrong!.
    The abbreviation kph is for the domain of the American AP guide only.
    The kph is in the dictionary, yes, we all know that too, it also says it is wrong to use it!

    Having said that, you are of course free to use whatever you choose, however to say that kph is what is on your speedometer is a very high improbability, an Imperial myth, and a misrepresentation of the facts, it is wrong.

    From your previous post ” … I simply ain’t got a clue with metric.”
    After a minimum 40 years of metric education in schools and metric used throughout the land for the same amount of time, I would say you have had ample opportunity to learn metric measures.

    It seems odd though, you can learn (presumably) Imperial, which is, to say the least, complex and confusing and not taught in school, but you ain’t got a clue with metric, which is logical and rational and taught (exclusively?) in schools. Well, it seems you have no intention of even attempting to learn and also seem proud of that fact.

    You can lead a horse to water, but you cannot make him drink. Again, your free choice I agree, but please do not try to pass it on to others that do like to try.

    I think we have a national crisis of education failure here, as I have suspected for some years now.
    I further think that Rt. Hon. David Cameron PM, and the others should take a long hard look at these failings and get things sorted.

    Of course with Cameron saying he prefers Imperial does not help one bit, but he should also take stock of the immeasurable harm it does to those of us with lesser brain, lesser education and fewer resources, that have to live with this problem of duplicity on a daily basis. We do not have an entourage of servants looking after our every need.


  29. @ Charlie P and Bodrules
    “kph” is nothing more than a sloppy anglocentric abbreviation of kilometres per hour. “km/h”, on the other hand, is a universally recognised symbol much like the McDonalds “Golden Arches” or the Mercedes three-pointed star. One of the many benefits of the metric system is that the symbols used are globally recognisable regardless of the alphabet of the country. Those that still subscribe to the parochial customary/imperial method of measurement cannot seem to get their heads around the idea of a method of measurement that is actually a system AND globally understood.
    “kph” may be a commonly accepted abbreviation in English speaking countries. “A Dyson hoover”, an ATM machine” and “less than five items” are commonly accepted phrases but they’re technically incorrect. All dictionaries accept “kph” but they prefer “km/h”. Why go for the least acceptable when it’s just as easy to go for something that conforms to the international symbol?
    If “kph” is an acceptable abbreviation you could argue that “qph” (quilómetro por hora in Portuguese) or “kpu” (kilometer per uur in Dutch) are also acceptable. But in my opinion they’re not because exceptions undermine the roots of the system which is to be universally understood. It’s a matter of getting your head around the idea of a system.


  30. @Bodrules:

    “Eh? You seriously don’t know that; mph = miles per hour kph = kilometres per hour. Simples”

    No, seriously, I know that kilometres per hour is correctly km/h. What does it show on your car? Is it kph or km/h and since it is km/h, why do you chose to go against the standard?

    I’m also perplexed as to how you can claim to not knowing metric when the environment around you is 80% metric. Do you not buy petrol? Do you not shop in the market and purchase prepackaged goods in metric only to rounded sizes? Do you not encounter weather reports? I’m sure you were taught metric in schoOl, so how is it possible for you to make such a claim?


  31. @BrianAC
    Bodrules’s speedometer will almost certainly use the symbol “km/h” on its kph scale, yes. I don’t think anyone (even Bod) was claiming otherwise.

    In English, “kph” is a commonly used abbreviation for kilometres per hour, yes. Similarly “blt” is a commonly used abbreviation for bacon, lettuce, and tomato sandwichs. Would you also say that the latter is a “sloppy anglocentric abbreviation” and that we could also use “bat” or “sls”, as the Portuguese for “lettuce” is “alface” and the Dutch for “bacon” is “spek” and for “lettuce” is “sla”.?

    Don’t you realise just how ridiculous the argument that “the English should stop speaking English if they are using the metric system” sounds?

    No wonder we are struggling to convince people of the cause, with logic like that being used in the discussion!


  32. @Charlie P
    Re “Don’t you realise just how ridiculous the argument that “the English should stop speaking English if they are using the metric system” sounds?”
    Why do you feel it’s necessary to anglicise something that is international? Something that’s intrinsic value lies in it being international? Would you like to see pictorial no entry signs revert to reading “No Entry”? I wouldn’t. I was taught by my Lancashire parents that if a job is worth doing, it’s worth doing properly and I’ve always stuck to that belief. I’m heartened to see you say “we” are struggling to convince people of the cause but I don’t think it’s necessary to accept compromises when something is as good as the metric system. The issue of parochial variations in terminology is no big deal in the big picture really but why not get the terminology right the first time? The term ‘degree Celsius’ was adopted internationally in 1948, yet when Celsius temperatures appeared in public forecasts in Britain for the first time in 1962 they were often referred to as Centigrade. You don’t hear that much these days as you don’t hear Nestlé to as “Nessels”.
    But why not get it right the first time?


  33. I find it surprising this point of kph v km/h should be a discussion. Long standing posters here may remember one of my very early, possibly my first post on UKMA, in which I was slagged of for using kph. I learned a hard lesson from that and try to ‘do better’. Being one of ‘the old folk’ it is not always easy adapting to change.
    However, to Charlie P in particular I put forward this: – If a person were to learn something new, say a word of a foreign language, or even a new word in ones own language, would an intelligent rational person attempt to learn that word correctly, or would said person deliberately go out of their way to learn the word wrongly (slang, colloquial)? Slang and colloquial is fine if you are just in one area, but not much help in the wider world.
    OK, if said person was learning metric, or a foreigner attempting to learn Imperial, would you expect them to attempt to learn correctly, or do you go out of your way to teach them incorrectly?
    Kilometers per hour is km/h, not kph. This old fart learned it the hard way, now get over it and do it properly, how hard can it be?


  34. The kph vs km/h argument is an example of the “abbreviation” vs “symbol” argument. Abbreviations are language-specific, symbols are language-independent. Although the Dutch might write “kilometer per uur” and the Portuguese might write “quilómetro por hora”, both use the symbol “km/h” on their road signs rather than language-specific abbreviations.
    I spent two years working in Germany and even though the German word for “hour” is “stunde”, never once did I see anything but “km/h” for “kilometres per hour”.


  35. @cliff
    I don’t “feel it’s necessary to Anglicise something that is international”. ‘Kilometres per hour’ is already pure English. Other languages have their own words, not all starting “k”, “p” or “h”, or even using the Roman alphabet, so why shouldn’t English? ‘Kilometres per hour’ most certainly isn’t international, even amongst English speaking countries – the Americans use ‘kilometers per hour’. But in English (even American English) the abbreviation ‘kph’ is entirely normal, common and legitimate.

    However, that’s not to say that I believe the ‘kph’ abbreviation should be used in otherwise language-independent situations, such as road signs. On those it clearly makes more sense to stick to internationally recognised symbols, including ‘km/h’.


  36. @Charlie P

    The spellings of metric units are NOT fixed across languages as you point out; however the symbols are. In the US, only the Associated Press accepts kph (and forbids the correct km/h).

    The US Government Printing Office Style Manual requires km/h as does the Chicago Manual of Style. FMVSS 101 requires speedometer scales to be marked as MPH and km/h, even though automotive writers follow AP practice and pretend the speedometer reads kph (which is forbidden by law). The MUTCD allows metric speed limits (although no state uses them excepts for a small number of demonstration signs). They require the numeral enclosed in a circle with the legend km/h underneath. NIST SP 330 (American version of SI Brochure) requires proper symbols and does not accept random abbreviations of metric units or prefixes.

    It is not considered acceptable in American English except to journalists and metricphobes.


  37. There are none so blind as those that do not wish to see.
    Therein is the problem.


  38. @Charlie P. Your words here fall on deaf ears. I used to argue them on this until I came to the realisation this was part of their dogma, one of their Ten Commandments (a fitting number, grouped on two tablets, five each).

    The question for which they haven’t a talking point is: How is the abbreviation (‘symbol’) verbalised? I have yet to hear an alternative to ‘Kay Pee Aitch.’ I used to take their argument more seriously, until I realised that the very same people contributing here had seen fit to inject their metric dogma and propaganda into Wikipedia articles as well! They really are quite shameless and incapable of objectivity and neutrality!

    Quite funny some of their arguments about ‘K.P.H.,’ vigorous though they may be, were easily refuted, I believe by A.C.W.M., making a brief image search for the term. It showed many countries with their own ‘abbreviations’ (Spanish, French, African languages) ALSO employing speedometers, signs employing K.P.H.

    I find the ‘debate’ here pedantic and amusing, but there is nothing funny about their injecting their viewpoint in what is supposed to be objective, scholarly work at Wikipedia. However, there appears to be noremedy to this, short of reducing myself to their tactics and wasting hundreds of hours of time to an article devoted to the metric unit of speed.


  39. @John Steele
    ‘KPH’ is not a symbol it is an abbreviation. And there lies the difference. ‘KPH’ is an abbreviation of the English-language name for the unit (not of the Portuguese or Dutch names) and as such is valid in English-language prose and even in speech. I agree that it makes sense to keep the unit symbol language independent (for road signs etc.), but abbreviations clearly do not fall into that category. Abbreviations, unlike symbols, are only used in single-language contexts. Compare ‘KPH’ with ”ETA’, ‘FYI’, ‘AKA’, ‘FAQ’, ‘TBA’, ‘DIY’. Or do you believe that we should only use language neutral versions of those too?


  40. kph vs km/h. The latter is much more common in Australia. I think it makes sense to use the international symbol.


  41. @ARM
    1. Who is A.C.W.M. ?

    2. Although Wikipedia does contain a wide breadth of material, and often comes high in search results, I tread carefully through its content – much of which is heavily biased, one-sided, promotional or plain wrong. I’d be interested to know though who you think is “injecting their viewpoint”, and how they are doing it.


  42. Cliff asked Charlie P “Why do you feel it’s necessary to anglicise something that is international?”

    This the essence of the kph versus km/h argument. We do not create a British version of the dollar sign ($) or of the euro sign (€). I have never seen other countries create their own version of the pound sign (representing the letter L of the Latin word libra meaning pound), so why pretend there is an ‘anglicised version’ of the international symbol for kilometres per hour? I think it is probably fair to say that kph has come about through ignorance, probably spread by journalists (in the USA and the UK) who, in my view, should check these things and should know better. The fact that it has become widespread in use does not grant it special protection. It is still as incorrect as a symbol as a capital P for pound sterling would be. (The international letter-based symbol for pound sterling is GBP, but that is of no relevance here.) Again, I think it is fair to say that most people do not understand the difference between abbreviations and symbols or signs. This is why you learn how to write things correctly at school. If km/h were widely in use, in other words on road signs, in the UK I am sure no one in their right mind would honestly be arguing that it is perfectly acceptable to write kph as an ‘anglicised abbreviation’. The question of how to ‘verbalise’ (or in English ‘say’) km/h, raised by ARM, like so many of their ‘points’, is a red herring. It is perfectly acceptable to say something like ‘I was 10 k over the speed limit’ and it is perfectly clear that you mean 10 km/h. If you want so ‘say the letters’, try ‘kay emm aitch’. You can visualise the stroke and you know to include it when writing the symbol.


  43. @Charlie P.

    ACWM is Americans for Customary Weights & Measures, the American version of BWMA. They always use kph and can’t bring themselves to utter the characters km/h. Using kph is a badge of honor for metric-haters.

    The SI has a rule book, called the SI brochure, unlike Customary and Imperial where no one is in charge and you can make up any abbreviation you please (we use “mi” for miles, while you use “m” but both use “M” in MPH; see, whatever the hell you want).

    Section 5.1 of the SI Brochure says this about that:
    “It is not permissible to use abbreviations for unit symbols or unit names, such as sec
    (for either s or second), sq. mm (for either mm^2 or square millimetre), cc (for either
    cm^3 or cubic centimetre), or mps (for either m/s or metre per second). The use of the
    correct symbols for SI units, and for units in general, as listed in earlier chapters of
    this Brochure, is mandatory. In this way ambiguities and misunderstandings in the
    values of quantities are avoided.”

    So if you use kph, you are not really using SI, you are using some bastardized units and we need to be suspicious of whether you are using any SI units correctly. The SI Brochure says nothing about the other abbreviations you listed and is only concerned with SI symbols. I would say Customary and Imperial should avoid abbreviations easily confused with SI, so British use of “m” for miles is about as bad as kph, but apart from that, use whatever you like for Imperial, use assigned symbols for SI.


  44. @Jake
    You missed the point completely.

    No-one (well not me, at least) is arguing that the abbreviation “KPH” should be used in place of the symbol “km/h” – where a symbol is most appropriate. All I’m pointing out is that in English, abbreviations such as “KPH” for “kilometres per hour” (and innumerable others, see my earlier post), are perfectly legitimate in English prose. What should be used on pictograms, in technical documents, etc. is an entirely different matter.

    As for your analogy with the £ or $ symbol, that would be fair enough if you were comparing it with the “km/h” symbol, but they are not comparable with the local language abbreviation. A better example would be, say, “value added tax” – “VAT” in English, “TVA” in French.

    To try to get one English abbreviation banned or somehow withdrawn or uninvented is a non-starter as English is an unregulated living language.


  45. Talking about currency symbols, they are still often used in a non-SI way: for example, “£ 400 bn”, instead of “400 G£” (gigapounds) – “customary” use sadly seems to prevail.

    In other words, SI is probably still too limited to science and engineering; while ideally, if it evolved, it could easily be extended also to other fields.


  46. @Jake:

    ” It is perfectly acceptable to say something like ‘I was 10 k over the speed limit’ and it is perfectly clear that you mean 10 km/h.”

    Indeed it is. In Canada, we would often say we were 20 kliks over the limit, but would never write it that way except in the most informal of communications (and not often even then).

    As an aside, in the early days of Canada’s metrication of its road signs, some officers actually did write (in ignorance) ‘kph’ when writing out a speeding ticket, and smart drivers would get the cases thrown out, on the basis that there was no such thing. Police officers soon learnt that they had to write ‘km/h’.


  47. @Sven G Talking about currency symbols, they are still often used in a non-SI way: for example, “£ 400 bn”, instead of “400 G£” (gigapounds) – “customary” use sadly seems to prevail.

    I am totally with you on this one. Further, this is far more relevant also, as the British Government uses the American ‘system’ of short measure rather than the English system of long measure.
    I have never really got my head round this one. Unlike Imperial’ where I can willingly ‘un-learn’ it and see a benefit, I can never see a billion as anything but what it is, bi millions put together = 1,000,000,000,000.
    That is as I learned it at school and I have never seen a sensible reason to change it. I never have and never will, use it myself. I don’t have that sort of cash anyway. I do not know how it would stand up in a court of law, given the sums involved.
    As you say, using M£ and G£ would be unambiguous and help the common usage of these units.


  48. @ JFL:

    I am sure British drivers would also quickly ‘wise up’ to the ‘technicality’ you draw attention to. The use of ‘kph’ is borne of ignorance of the proper way to write ‘kilometres per hour’. It is as wrong as MpH, M/h or any other variation on a theme would be for miles per hour in the UK (the Americans often write M.P.H., I believe). It is no more the product of an ‘unregulated living language’, as a poster above calls it, than the spelling ‘accomodation’ is. That particular misspelling was very prevalent for years and years in British tourist resorts. That did not make it correct. And English ‘is’ a regulated language, unless you wish to invent your own spellings (though words with alternative spellings do exist of course). But I diverge. As another aside, I had a speeding ticket in Flanders once which showed my speed in ‘km/u’ (kilometers per uur). If SI applies in Flanders (and it does of course), that should have been km/h. However, not wishing to launch a legal battle with the Flemish authorities, and accepting that I had been speeding, which is more to the point, I paid up at once.


  49. @Jake
    You said “The use of ‘kph’ is borne of ignorance of the proper way to write ‘kilometres per hour’.”

    You are wrong, it is normal English usage, and is fully documented, and accepted as such, in all the mainstream English dictionaries that I could find (unlike misspellings such as ‘accomodation’)

    It is true that the SI brochure frowns upon the use of such abbreviations in “scientific and technical papers”, which is fair enough, but that is an entirely different kettle of fish to normal everyday English usage.

    And no, English is not regulated; French is, and I believe some other languages are, but English is not. There may be certain conventions and recognised spellings, but these change as usage develops. There is no body or committee deciding what can and cannot enter into mainstream usage (which does exist for French). The dictionaries follow and reflect usage, they do not prescribe it. If usage of ‘kph’ ceases some day, then the dictionaries will eventually reflect that, but for now it is undeniably acceptable current usage.


  50. @ Charlie P

    Yes, you will find ‘kph’ in dictionaries, reflecting usage, as you say. The Concise Oxford dropped the entry some years ago when I pointed out to them that their book cover called the dictionary ‘the most authoritative dictionary in the English language’. It is true that people quickly turn to their dictionaries to prove a point, as you do, but unless a dictionary is genuinely authoritative it merely shows how people use words rather than how they should use them. That includes both spellings and symbol use. That dictionary now only lists km/h. Admittetly, I have not made a point of writing to all dictionary publishers. English is regulated by use, but that does not mean that anything goes. As for your continued insistence upon upholding the validity of ‘kph’, I can see no logical reason to support a mis-symbol when a real one exists. And please do not repeat that ‘kph’ is an abbreviation not a symbol; I know your view on that. I doubt whether that distinction is understood among the public at large. That is why people often write metric speeds as e.g. ‘xxx kph’. They can be forgiven for thinking that is correct if they see the symbol incorrectly written all over the place. But extensive incorrect usage does not make it correct, as extensive incorrect spelling of words does not make those spellings correct either.


  51. To return to the subject of the original article, whilst it was a good thing to encourage people to think metric, I would not agree with the approach taken by CITB.

    The poster featuring the human foot reinforces the myth that the imperial unit of the same name is representative of its size and a convenient way to visualize it. The measurement unit is significantly longer than a typical human foot.

    The bikini poster sends entirely the wrong message because it encourages soft conversion with no regard to the accuracy of the original measurement. The figure of 914 mm implies that the original measurement in inches was accurate to 1/25th of an inch.

    More generally, in order think metric properly, it is important to learn to visualize the world in convenient rational numbers. In the case of the lovely lady, 900, 600, 900 would probably be adequate.

    The exclusive use of the mm rather than cm is a good idea in the right context but its advocacy has led to some common misunderstandings, e.g. that cm is not an SI unit.


  52. Another useful exercise is to identify a road in your home area which is one kilometre in length. This is a simple exercise for Her Majesty – she need only go onto the balcony of Buckingham Palace and look up The Mall (or should that be “The Royal Kilometre”?) – measurements made using Google Earth suggest that the distance from the middle of the Victoria Memorial to the far side of the central arch in the Admiralty Arch is exactly one kilometre.


  53. @Philh I agree on the foot, anyone with feet of approximately a foot long would have serious trouble buying shoes!

    As for that bikini poster, sizes in millimetres are nonsensical. First of all it implies an accuracy that is not realistic, and the numbers are way too big for any meaningful use. That’s why clothing sizes tend to be given in centimetres. Look at this H&M size guide for instance: http://www.hm.com/nl/sizeguide/sizeguide_ladies All measures are in centimetres except occasionally inches for jeans, probably because they are an American invention.

    I think the only place where millimetres might come in handy would be in shoe sizes where that level of accuracy might some times be relevant.


  54. Actually, S, M, L, XL and so on (of “American” origin?) probably are more intuitive for clothing: they should be adopted by the SI 😉 🙂


  55. @Jake
    The current Concise Oxford gives “km/h (also kph): abbr. kilometres per hour.” The definitive full OED gives “k.p.h. n. kilometres per hour.” So kph is fully endorsed as current usage by the most authoritative dictionary of English usage. Hence it is by definition correct usage – what more can I say!


  56. One of the objections to metrication in the early years was the excessive use of millimetres. The start of the British metrication program was in 1965, only five years after the introduction of SI. The EEC (as it was then) was getting to grips with SI and in 1971 published Directive 71/354/EEC making SI the legal system of measurement within the EEC rather than CGS-based and gravitational-based systems of units. This required the discarding of a host of non-SI “metric ” units including the poise, erg, dyne, standard atmosphere, Pferdestärke (also paardekracht, cheval vapeur and cavallo vapore), calorie, kilogram force and many others. (The directive can be viewed at http://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:31971L0354&qid=1441144704069&from=EN). Like the EEC, the British Metrication Board was sailing in “unchartered territory” in judging how best to handle SI and whether or not the prefix “centi-” would die a natural death.


  57. @ Charlie P who wrote: “So kph is fully endorsed as current usage by the most authoritative dictionary of English usage. Hence it is by definition correct usage.”

    Listing a term in a dictionary is not the same as endorsing it and it certainly does not make it correct or preferred usage. You are right in saying that kph is included as it is ‘used’ as an abbreviation. I have no problem with that argument. But the problem is that the people who ‘use’ that abbreviation (e.g. journalists) are often the people who do not know that there is a proper symbol for kilometres per hour. I am not aware of this problem existing outside of the English speaking world. If metric usage on road signs were properly established in the UK, people would, I am quite sure, not be writing kph.


  58. CharlieP wrote “So kph is fully endorsed as current usage by the most authoritative dictionary of English usage. Hence it is by definition correct usage – what more can I say”. I remenber reading that somebody in Ireland got a speeding fine quashed because the ticket read “kph”, not “km/h”, so I checked what Google had to say. When I applied the filter “kph site:.ie”, I got 68,000 hits, many of which were related to a construction company KPH. Applying the filter “km/h site:.ie”, I got 1.1 million hits. This suggests to me that “kph” is not accepted in legal circles.


  59. @Jake

    In English, dictionaries do not endorse use, they simply document it. The entry is evidence of common usage – and who are we to judge that usage as correct, or otherwise?

    The only time we should be critical of usage is in technical scientific and engineering reports and papers. Journalists are not tied by the SI style guide, which as the SI brochure puts it, is for “scientific and technical papers”.

    And what makes you think that metric road signs would make much difference in the UK? Australians, Canadians, Irish, New Zealanders all also commonly use non-SI-endorsed abbreviations such as “kph”. And it isn’t only English speakers that treat the SI brochure with the contempt its inflexibility brings on it. It isn’t hard to find “k” (kilometres) and “kilos” (kilograms) being used in other languages too.

    If we are to progress, we must accept that insisting that everyone adopts that unrealistically inflexible writing style is a non-starter.


  60. Charlie P showed that the Concise Oxford Dictionary gave first place to km/h. This means that km/h is preferred over kmh. The fact that the OED gives k.m.h. demonstrates that it is behind the times.


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