The battle for measurement supremacy

In December 2015, television weather forecasters expressed our record rainfall in millimetres while the national newspapers stubbornly stuck to inches. Apparently, the use two different measurement systems for the same phenomenon is alive and well in the UK. Ronnie Cohen looks at other aspects of British national life where two competing systems are used for measuring the same thing.

Car park signs


The UK Department for Transport (DfT) insists on using yards for car park signs while private sector car park signs are normally metric. The left sign contains an official-looking P sign in a square box.

Vehicle dimension signs




It is common to see both the imperial and metric versions of vehicle dimension signs alongside each other on many of Britain’s roads. However, the vast majority of private-sector vehicle dimension signs are exclusively metric. By insisting that the metric-only versions of these signs cannot appear by themselves on official traffic signs, the DfT is out of step with private practice.

Dual versions also exist for width and height vehicle dimension signs on British roads.

Walking and cycling signposts


The signposts are intended for cyclists and walkers. Most signposts are in imperial units. However, there are a few in metric units.


There are also a few dual signposts like the one shown above. One thing that is notable about the imperial and dual signs is the erroneous use of “m” for miles, influenced by the DfT’s use of “m” for miles on official traffic signs. The symbol “m” should only be used for metres, not miles, but some might argue that it is merely an acceptable abbreviation.

Tourist signposts


I took this picture outside Baker Street underground station in London. It was one of the most bizarre pictures I have ever found relating to British measurement muddle. That picture shows two signs to Madame Tussauds tourist attraction, one giving a distance of 100 metres and the other giving a distance of 370 yards. Surely, one of these signs is wrong. Once again, the private sector opts for metres which will readily be understood by overseas visitors while Transport for London uses yards, no doubt influenced by the DfT use of yards on all official road signs. I wonder what tourists would think of such muddled signage.

Fruit and vegetable prices


I found all three signs shown above in the same shop in Golders Green, London. I could not believe that a single shop uses imperial-only, metric-only and dual pricing. This is unbelievable. I have seen this kind of thing in different places but I have never seen it all in a single shop. I pity the poor shoppers who have to mentally convert prices from kilograms to pounds or from pounds to kilograms to compare prices just to find out what is better value for money. This could be avoided by using just one system of weights for pricing. Legally, kg must be used but lb can optionally be used alongside kg.

Gold sales

Gold bar - 1 g

I found a vending machine at Westfield White City shopping centre where gold bars were on sale in quantities of 1 gram, 2.5 grams and 5 grams. Gold is sold and priced in troy ounces in commodity markets. Turn to the financial pages in almost any British national newspaper and you will find gold prices quoted in troy ounces. Before I saw this vending machine, I did not know that gold was also sold in metric quantities.

Tyre pressure

Tyre pressures are commonly measured in bars and pounds per square inch. You can find both for tyres. This is a good example of two competing systems, neither of which is widely understood.

Railway systems

Railway use of miles and chains

I took the picture above at a train station. It shows a measurement in miles and chains. While legacy railway systems use miles, chains, yards and miles per hour, modern railway systems such as the Channel Tunnel Rail Link (a.k.a. HS1) and tram systems use metric units.


Some sports such as rugby union, swimming and athletics use metric units worldwide while other sports such as football and horse-racing use imperial units in the UK.

Fuel efficiency

Fuel efficiency is given in both litres per 100 kilometres and in miles per gallon. You can find both in car advertisements.

Land areas

For large areas of land, especially farmland, acres compete with hectares for describing land area. While hectares are used officially, acres are in common use for farm sizes and among estate agents.

Similarly, when describing the floor area of offices and residential property for sale or rent, agents will use square feet or square metres.



Of all drinks products sold in British shops, milk is the only one where the word “pint” appears. It is now rare to find pint-based sizes for any other drinks in the shops. Milk is the notable exception where litres and pints are both used for ranges of rational container sizes.

Beer, wine and spirits


While pubs serve draught beer and cider in pints and half-pints, as they are legally obliged to do, packaged beer and cider drinks are predominantly sold in rational metric sizes. Pubs commonly sell beer and cider in bottles too, which are sold in metric sizes. It is awkward to compare value for money when some pub drinks are sold in metric quantities and others are sold in imperial quantities.

Wine and spirits are of course sold in pubs in metric measures.

This is a reminder that the measurement mess in the UK is alive and well and shows no signs of disappearing by itself. Without government action to resolve it, this mess will remain. Despite the fact that 50 years have passed since the start of the UK metrication programme, so many aspects of life remain a mixture of metric and imperial, including estate agents, small shops and market traders, official traffic and other public signs and much product advertising and descriptions. Currently, there appears to be no end in sight to this UK measurement muddle. When the authors of Magna Carta wrote “let there be one measure” could they have imagined the mess that would exist 800 years later?

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42 Responses to The battle for measurement supremacy

  1. Rob says:

    Another very interesting article, maybe your local newspaper or even a national newspaper needs to publish it or email it to your MP!
    It seems to me that most members of the public (and MPs) do not recognise that a measurement mess exists.

  2. John Frewen-Lord says:

    I was under the impression that height and width signs had to be posted in both imperial and metric, especially on routes experiencing trucks and lorries from mainland Europe. There are a number of sections of the A180 between Barnetby (end of the M180) and the exit to Immingham (a very busy international port), where there are currently extensive road works, including an 18 month long interchange reconstruction. Astonishingly, these road works have outside lane width restriction signs in imperial only (specifically 6 ft 6 in, or about 2 m). Now the typical truck is 2.5 m wide, which means they should not be using the outside lanes at all.

    But the non-British ones are. And in doing so, they run into the problem of insufficient width when two of these trucks end up side by side where there is just not sufficient room for them. I was recently in the outside lane following a lorry on Polish plates. Not only was he exceeding the 50 mph / 80 km/h speed limit through these road works, but he all but side-swiped the lorry beside him as the lanes narrowed down. He then braked sharply, causing me to brake heavily also - and I was all but rammed from behind by the car following me.

    Once again, I say - time to end this madness of a country using two sets of measurement units. Metric is here to stay - 95% of the world's population uses it, and it is often the only official measurement permitted in almost all areas of life in the UK, and even in many areas of life in the USA. The DfT needs to be brought into the 21st century, and made fit for purpose by outlawing non-metric measurements on road signs.

  3. BrianAC says:

    I can pick up on the gold price issue.
    Gold coins are, as 'the other lot' would say mostly in 'traditional' troy ounces (toz, 31.1 g). Only the Chinese gold coins will be all metric from 2016 onwards. As coins are historic, this is perhaps understandable.
    Most gold bars are now in rational metric measure. Eleven sizes of rational gram (includes the famous 12.5 kg brick), only 4 sizes of ounce and 2 of Tola (11.66 g). All weights are supplemented with the metric gold content leaving no doubt that a toz is 31.1 g.
    Once again, I would say this is the difference between the printed media and the real world.

  4. Ronnie Cohen says:


    The UK Metric Association (UKMA) has lobbied extensively on clearing up the measurement mess and continues to do so. As well as UKMA publications, countless Metric Views articles have been published about the measurement mess and the problems caused by running two competing, incompatible systems in parallel. UKMA continues to raise this issue with politicians and other decision makers. They know about the measurement mess but there is a lack of political will to do anything about it and the media lacks interest in raising this issue. I would be delighted if the media published my articles and if politicians took an interest in what I write on Metric Views.

  5. Charlie P says:

    @John Frewen-Lord

    You seem to be implying that it is only non-British trucks breaking the width restriction and that they are only breaking it because the driver doesn't understand the units on the signs. Do you have an evidence to show that these law breaking foreign drivers would be more compliant if the signs were in metric?

    Because surely if they were, they would slow down to 50 km/h (or less) when they saw a "50" (they don't even have units on them) speed limit sign, not going at more than 80 km/h! You can't have it both ways.

    Perhaps they have a different attitude to road laws where they come from, or perhaps they just think they are outside of the reach of UK road law enforcement, so don't attempt to comply when it doesn't suit them. We need to know which it is before jumping to ill-conceived conclusions.

  6. Alex Bailey says:

    I was under the same impression… I noticed the same imperial-only restrictions in roadworks in Northumberland a few weeks ago - I can’t recall the exact roads and locations but one may have been the A1(M) and many of the signs looked new.

    I also saw many of the same on the M3 near it’s junction with the M25 towards the end of last year.

    Years ago when I pointed out to the Highways Agency in Hertfordshire that, although not mandatory the Traffic Signs Manual actually recommends dual-unit signs I was told “Our contractors don’t like to use them because they are larger and heavier to move so cause health and safety issues”. I wonder if this is still the excuse. What about the health and safety of drivers?

  7. Jake says:

    Charlie P asked JFL: 'Do you have an evidence to show that these law breaking foreign drivers would be more compliant if the signs were in metric?'

    That isn't the point. It would certainly be a mitigating factor in legal proceedings if a driver maintained that he did not understand the imperial width restriction sign. It does not follow that the driver would automatically assume that '50' meant 50 km/h and be driving at that speed in such a marked area. No responsible driver assumes he is outside of the reach of national road law enforcement, whatever country he is in. What bothers me is that the outside width restriction of 2 metres in roadworks is generally standard across the EU. Any foreign haulier driving in the UK should know that. And the converse applies to British drivers on the continent. I would hazard a guess that the Polish driver was simply in the wrong lane. No only do foreign hauliers have imperial signs to contend with but they are driving in a mirror-image of the road layout in continental Europe where traffic drives on the right side of the road.

  8. Martin Vlietstra says:

    I am surprised at the number of vehicles that break the 6ft 6in width limits around the countryside, especially when I do not think that the drivers concerened are aware that they are doing so, for example the Range Rover Sport - width with mirrors folded in - 2018.5 (79.4). Dimensions (taken from their website) are in "mm(in)".

    BTW, is 79.4 inches less than 6ft 6in? On the same topic, is 2018.5 mm less than or greater than 2.0 metres?

  9. Americans for Customary Weight and Measure says:

    The notion that Poles are only capable of figuring in metric amounts is both absurd and insulting! Are you saying there is something to the "Dumb Polock" stereotype? B)

  10. John Frewen-Lord says:

    @Charlie P:

    You are conflating two entirely separate issues. Foreign drivers probably, though perhaps not always, know quite well what a '50' sign means in the UK - and probably also understand what it means in terms of what speed they should be travelling at. OTH, while foreign drivers MAY know that 6' 6" (which is what is shown on the width signs) means 6 imperial feet followed by 6 imperial inches, they quite likely have little idea what it means in terms of determining the width available to them.

    As for exceeding the speed limit, it would seem that this particular driver didn't even know what 50 meant - this stretch of road has SPECS average speed monitoring, the police patrol it quite heavily, and you routinely see foreign-registered LHD lorries pulled over into lay-bys with a police car in attendance. Didn't stop this Polish driver slowly pulling away from me as we entered the 50 zone, until he had to slam on his brakes else he would have hit either the median barrier or the truck beside him. In short, imperial measures are not fit for purpose on Britain's roads.

  11. Martin Vlietstra says:

    @CharlieP: If a driver who is not familiar with the imperial system uses the simple conversion of two kilometers equals one mile, then they will interpret 70mph as 140 km/h which, although it will attract a speeding ticket, does not automatically cause an accident (unless accompanied by reckless driving). On the other hand, an HGV driver who makes the assumption that there are three feet in a metre is just looking for trouble when they approach low bridges - a 12 ft bridge could cause a lot of problems with a 4 metres high HGV.

  12. Jake says:

    @ ACWM

    As usual, you have gone off on a tangent and missed the point. First and foremost, no one here, as far as I can see, is trying to insult Poles in any way. The fact is that unless a Pole had had regular and prolonged exposure to imperial or customary units of measurement, for example by living in the UK or the USA, he or she would very likely not understand them when confronted with them. I say this even though in the UK there is a saying that 'ignorance of the law is no defence', i.e. you can reasonably be expected to understand the road signs if you are driving on the roads in the UK, even if in actual fact you don't understand them because you have never been exposed to or taught imperial units. That would be a reasonable defence in law if you failed to observe a particular sign, as it would be a defence if you didn't understand a sign in English. (I wonder how many Americans visiting Poland understand signs in Polish unless they have Polish roots? How many Americans understand road signs in any language other than English?) The Polish lorry driver in the article should have known that the outside lane was only going to be 2 m wide, whatever the sign said. You remark about 'figuring in metric amounts' is however absurd: how long does a 'truck driver' moving at speed have to convert an imperial sign in his head to the metric he knows, or to consult a conversion chart? Not very long. It would help if the sign carried the information in metric units. Most drivers in the UK are now of an age where they have learnt those units at school. So I agree with JFL above who writes that imperial measures are no longer fit for purpose on UK road signs.

  13. BrianAC says:

    @Americans for Customary Weight and Measure says: 2016-03-01 at 15:45
    "The notion that Poles are only capable of figuring in metric amounts is both absurd and insulting! Are you saying there is something to the “Dumb Polock” stereotype? B)"

    Now I say, "Why would you expect a Polish truck driver to be able to understand what 6'-6" meant in the first place?"
    Now assuming he (or she) had driven far enough in UK to sort of work out what 6'-6" did meant, there is no way on God's Earth he would be able to relate that to the width of his own vehicle, he would simply not have a clue.
    It seems totally bizarre to me that you seem to assume that 'everyone in the world' can estimate and calculate in Imperial units!!!
    Nothing dumb about it whatsoever, please do come back and explain (and anyone else for that matter) why you, me, we or anyone else should expect a 100% metric educated truck driver to understand, estimate and/or calculate in feet and inches.

    You may be hard pressed to find a UK educated truck driver that could do all three of those things (and whilst driving on a UK motorway to boot). They are after all 100% metric educated (supposedly).

  14. Bonus Miles says:

    The TfL sign pictured must be quite old - London Underground maps show distances between stations in metres and there are many instances of station signs showing distances to other landmarks in metres too.

  15. Ezra Steinberg says:

    The point is effectively made in previous posts that there is not nearly as much room for error when it comes to width restrictions as there is for speed restrictions. And calculating widths from Imperial to metric on the fly is quite the challenge for most people, especially when you are driving a heavy-goods vehicle at speed (or more!)

  16. Charlie P says:

    Wrt foreign truck drivers disobeying UK road signs, it's all down to training and professionalism. If they cannot cope with the UK's road system they should not be using it.

    The UK, who generally use imperial measures on road signs, consistently appears at the top of the IRTAD tables of road safety by OECD country. On the other hand, Poland and Lithuania, who use metric measures, consistently appear at the bottom end of of the tables.

    I would contend that it is NOT the units of measure used on road signs that are the root cause of any safety issues with these drivers.

  17. Alex Bailey says:

    Interesting that the intelligence of the Poles is brought into question here since it’s often the intelligence of Brits (and Americans) being insulted by suggesting we’re too stupid to learn metric.

    My own experience travelling the world is that, having been educated almost entirely in Metric during my education in the UK, I have zero issues in almost all countries. In the UK I manage by approximating 1 yard to 1 metre in most cases but clearly width limits in feet and inches start to become more interesting, more so when the owners' manuals for my last two cars (both Vauxhalls) only show vehicle dimensions in mm.

    Worse when I travel to the USA, I always seem to get a mental block the first time I have to fill a rental car, having to pre-pay because the gas pumps won’t accept UK credit and debit cards, I’m always stumped when trying to figure out how many gallons the tank will hold (I never have this issue in Canada). And then having to cope with those “lane closes in 100 feet” signs too; seeing one of these at 75 mph on the interstate when you’re trying to pass somebody is always a joy. And I’m in a country that some try to convince me still uses those measures (the same people who seem to ignore the fact that the gallon is different and then go on to complain that American pints of beer are weaker because it takes more of them to get drunk).

    I also now think of the German HGV driver who just last week, in road works on the M1 in Bedfordshire, passed me in lane 3 at a speed far higher than the 50 mph maximum. Drivers from all countries do stupid things because they’re impatient (or just idiots) but at least having consistent warning signs on the roads would reduce the chance of unintended error by the less experienced.

    Then there’s the stupidity of those green emergency exit signs that have been installed in tunnels throughout the UK being in yards. I’ve actually seen some of these in one tunnel somewhere recently (I don’t recall where) where they were actually in metres!

  18. Ronnie Cohen says:

    @Bonus Miles

    You are right about TfL's use of metres on London Underground maps. I have also seen metres used at the station exit of Sloane Square station and on pedestrian signs in Greenwich. However, many TfL public signs in London streets and at and near station exits show yards. There are others that show minutes to destinations for pedestrians. So there is a mixture of yards, metres and minutes for expressing distances for pedestrians in London. TfL measurement usage is a big mess. I wonder what the millions of tourists who visit London think about our measurement mess.

  19. Ezra Steinberg says:

    Given the apparent prevalence of metric on private distance signs, one can only imagine how decisive a switch by the DfT to metric signs on UK roadways would be when it comes to moving the UK to being almost entirely metric in short order (especially in the light of how things played out in that way when the Irish Republic converted their road signs to metrtic).

    A task for the next government I presume (whenever that might be).

  20. Jake says:

    Alex B wrote: "Drivers from all countries do stupid things because they’re impatient (or just idiots) but at least having consistent warning signs on the roads would reduce the chance of unintended error "

    Having warning and advance notice signs in consistent units would also remove the legal defence of not understanding the signs or, more to the point, the units on them. The UK is part of a Europe-wide road network. Many continental HGVs are simply driving through the UK on their way to Ireland. It is really insanity to have an island of road signs that most continental European (and increasingly British and Irish) drivers do not understand. That insanity is doubled when it is considered that most UK drivers have been taught metric but because of the road signs probably quickly forget it all again after leaving school (unless they work in a job that involves measurement). If you were setting out with a blank piece of paper to create a Europe-wide road system you would not start by putting an island into it with a different set of units on the signs to the rest of the system. It is not the case (as Charlie P) maintains that if they 'cannot cope' with the UK's road system roads signs they shouldn't be using it. That is like saying if they can't speak English they shouldn't be in the UK. Metric units are an international language. We learn it at school so why don't we use it on the roads?

  21. Michael Glass says:

    People brought up using metric measures do not automatically understand imperial measures just as people who are used to imperial measures don't automatically understand metric measures. This is most critical in issues involving heights and widths. Hence the disproportionate number of foreign trucks crashing into low bridges on UK roads.

    This has prompted the authorities to provide dual signing for heights and widths on roads. it's a case of practicality outweighing tradition. However, it's certainly a cause for concern that this is not always put into practice.

  22. Martin Vlietstra says:

    The document "Impact Assessment of the Traffic Signs (Amendment)
    Regulations and General Directions 2010 and of the
    Traffic Signs (Temporary Obstructions) (Amendment)
    Regulations 2010" at states that "Based on records from Network Rail’s incident logs since April 2008, approximately 10 – 12% of bridge strikes involved foreign lorries. This is disproportionately high in terms of the number of foreign lorries on the road network." (para 55).

  23. Jackthesmilingblack says:

    How about a ruling on the plural version of abbreviations: As example, yd(s), oz(s), kg(s), km(s) ...

    Editor. Abbreviations are rarely used for metric/SI, which prefers symbols. These do not change in the plural eg 0.5 m, 1.5 m, 15 m. The SI brochure, downloadable from the BIPM web site, explains all.

  24. John Steele says:


    As mentioned above the SI defines symbols which do not use periods or change in the plural; abbreviations are not permitted.

    In the US, the FPLA (net contents law) states plurals and periods are optional for abbreviations of Customary units, but are not permitted for SI units. Not sure if the UK has direction on Imperial abbreviations.

  25. Martin Vlietstra says:

    The UK law has not, as far as I am aware, issued any directives on the use of symbols for imperial units, but if there a legal dispute were to arise, then EU directive 80/181/EEC (text at could come into effect. The last two pages catalogues the symbols "min", "h", "d", "mile", "yd", "ft", "in", "pt", "oz tr", "fm", "pt", "fl oz", "gill", "oz", "lb" and "therm" as being allowable symbols in circumstances where the units themselves are allowable. I believe (though I am open to correction) that these symbols all came from an early version of ISO 31 (but are no longer used by ISO).

  26. Daniel says:

    @John Steele

    To the best of my knowledge, there was, is and never will be any common, completely acceptable unit symbols or either imperial nor USC units. It's a free for all. Pick what you want and as often as you want, nobody cares. The bad part is when this attitude is brought into metric with such trash as kph.

  27. Percy says:

    Martin's comment [2016-03-30]

    I note that for the 'mile' the symbol is 'mile'.
    As far as I'm aware this is the first time that an official document gives a unit name as the symbol for that particular unit.
    We all know that 'm' is the symbol for 'metre'; so therefore, IF 'm' appears in any official document or on a road sign perhaps legally it does not, or should not, be regarded as the symbol and/or the abbreviation for 'mile'.

  28. Mark Williams says:

    @Ronnie Cohen:

    Possibly the `yds' are thinly obfuscated imperial feet intended solely to benefit visitors from the USA and baffle everyone else, including the natives. That whole TFL sign is a case study of illegible London. It is what you get when you put committees of liberal arts graduates/ PR types in charge of signage instead of scientists and engineers---fanatical attention to detail when it comes to typeface and colour palette, but no apparent interest in accuracy of information or clarity of expression. The planetarium is no more, and which way are those arrows at the bottom pointing?

    The presumably private sign could do better, too, by using the internationally understood symbol `m' instead of the English/ French word `metres'. But, as you rightly point out, use of `m' as an anachronistic and heavily contrived abbreviation for imperial miles on DFT-style signs is a recipe for confusion. Parenthetically, the only obvious explanations for the relatively recent introduction of that into TSRGD (supposedly limited to some motorway signs, IIRC) are monumental ignorance or deliberate nastiness on the part of its liberal arts graduates/ PR types.

    I suspect many tourists ask `do these people clean or maintain' before, during and after seeing these examples.

  29. John Steele says:


    Well, people can pick what they want and nobody cares, but, in my opinion, there is an official set. On 1968-07-29, NBS (now NIST) read into the Federal Register their authority, delegated by the Secretary of Commerce, to define and interpret both Customary and metric systems as used in the US (it is also App. 8 of NIST SP 447). That original publication uses no abbreviations, only full words for units. However, NIST annually publishes substantially the same document as NIST Handbook 44 Appendix C, where abbreviations for each unit are included (they are in agreement with rules for FPLA and UPLR). I consider those the official abbreviations for the United States, even if random, made=up ones aren't a criminal act. FMVSS 101 designates MPH and km/h as the only allowable units and markings on a speedometer, it would be a criminal act for an automobile company not to comply. Sorry, Charlie.

    The US uses largely the same list of abbreviations. Exceptions: "mi" for mile, never "m,", "oz t" for troy ounce, and we apparently don't have an abbreviation for fathom. (Source: NIST Handbook 44, App C)

  30. Charlie P says:

    @Daniel 2016-04-02 at 01:02

    Let's try to be clear with our terminology here - "kph" is an abbreviation, NOT a symbol. As such, it is widely (and correctly) used in prose (if it were used in scientific and technical papers that would be an entirely different matter) - as with "kilo" for kilometre or kilogram, "sec" for "second" .

  31. John Steele says:

    @Charlie P,

    The SI is not just for scientific and technical papers, it is a measurement system for (nearly) all mankind. It forbids abbreviations. If you are not going to use SI, just use Imperial, don't misuse SI.

  32. Charlie P says:

    @John Steele 2016-04-08 at 00:49

    You wrote "The SI is not just for scientific and technical papers", as if I had suggested something different!

    Please don't confuse or conflate the SI per se (the system of physical units) and how it has been incorporated into British lore and language with how the style guide presented in the "SI Brochure" recommends it be used or written in scientific and technical papers.

    Outside of specific regulated domains, there are no restrictions on how the English language is used in the UK, so please do not try to suggest otherwise, and certainly don't try to imply that the SI realm is somehow more important than any other realm in English or that the SI Brochure, or its recommendations, has some sort of special status or weight where it has not.

  33. Alex Bailey says:

    I personally believe the use of kph instead of km/h in places like newspapers or text books where facts and spelling should be properly checked to be no different than if those same publications allowed text speak such as “u”, “ur”, “thx”, “gr8”, etc.

    It does nothing more to me than indicate either ignorance, poor education, laziness, or a combination of all three.

  34. John Steele says:

    @Charlie P

    Your insistence the Style guide (chapter 5) in the SI Brochure ONLY applies to scientific and technical papers implies EXACTLY that. It is a part of the Brochure and part of correct usage of the SI.

    If you don't follow it, you are not really using the SI but rather some mutated version of it. As far as I am concerned, that is equivalent to misusing English, bad spelling, bad grammar, and also, I suppose, math errors. Certainly many people misuse English, writing and speaking bad English. so I suppose you have a right to misuse the SI as well. However, people are far more understandable when they use both correctly (more bluntly, they look foolish when they don't). Deliberately misusing it when you know better seems to be a tool of pro-Imperial people and a way to poke their finger in the eye of the SI.

    We also only regulate speech in certain domains, but it leads to inconsistencies. Automotive writers speak of speeds in kph because the AP Style Guide REQUIRES the SI to be misused, while motor vehicle law requires the metric ring of the speedometer (if the car has one) to be labeled as km/h. No US driver has ever seen a "kph" in a car. Does that provide clarity or prove the AP are idiots? (my answer is "B.") If a unit is consistently labeled one way in cars and on signs, by law, does it really make sense to call it something else in the media?

  35. Charlie P says:

    @John Steele 2016-04-15 at 11:10

    The SI style guide only applies to those who choose to adopt it or in situations where its adoption has been mandated by regulation or contract.

    It even makes its intended scope clear in its introductory paragraph: "Compliance with these rules and style conventions, the most important of which are presented in this chapter, supports the readability of scientific and technical papers." It doesn't mention other situations, or even purport to have a wider audience, so why should we pretend anything different?

    People aren't (generally) idiots or machines. We can understand both "km/h" and "kph", "kg" and "kilo", "km" and "k" and even "kms", "mtrs" and "ltrs" - from context.

    Concentrate on the real issues and UK acceptance of metrication may well happen sooner, but this continuous knit-picking over the irrelevant trivia will only delay acceptance further.

  36. Rob says:

    Just viewed the all new BBC TV Top Gear motoring programme.
    With the up to date programme and a new set of presenters we still have imperial performance attributes for vehicles quoted. Is this against the BBC charter?

  37. Jake says:

    Charlie P wrote: 'We can understand both “km/h” and “kph”, “kg” and “kilo”, “km” and “k” and even “kms”, “mtrs” and “ltrs” – from context.'

    We can also understand *mis-spellt* words, wee duh eet al the thyme.

    Seriously: taking the examples given, 'km/h', 'kg' and 'km' are proper SI symbols in their own right, even if the average reader may mistakenly think they are abbreviations. 'kilo', 'k', 'kms', 'mtrs' and 'ltrs' (and let's add 'mls') are shortened forms of whole words and, yes, can be recognised and are commonly used as written forms of the names of metric units (e.g. 'a 2 kilo joint, a 5 k race, 'turn left after 100 mtrs'). They are metric units as they are spoken and often written and, frankly, I have no great problem with them. But I do, and I suspect others may too, harbour a particular loathing for 'kph'. From the brief research I have done it seems it is more widely used in the USA (even appearing in published fiction), often with stops between the letters, so 'k.p.h.', probably because Americans use stops between the letters 'm.p.h.' and thus follow the same pattern. I am sure my loathing of 'kph' stems from the fact that I so often see it in articles published in the UK on subjects such as motoring which, in a broad sense at least, can be called 'technical' articles. Technical authors generally tend to get things right, but there seems to be a block when it comes to kilometres per hour. And supporting the 'wrong' side of the debate, by claiming that people understand things 'in context', doesn't really clarify anything, but only serves to entrench the mistake and make it seem acceptable.

  38. Ronnie Cohen says:


    I share your frustration with the continued use of medieval units in so many aspects of British life, including car performance statistics. Despite the fact that all modern cars are designed and built exclusively in metric units, they are almost always advertised using medieval units in the UK. One thing that is concealed from the British public is that none of these non-metric units is ever used for designing and building modern cars. Speedometers and odometers are only calibrated in statute miles to meet British legal requirements. The use of non-metric medieval units on official traffic signs and in British legal requirements and, as a result, what the British public is used to and perceived to understand well are all factors that strongly influence the usage of particular units for advertising cars in the UK. The strange thing about the use of medieval units on official traffic signs is that even the digits showing the medieval units are exclusively designed in metric units and so are the all the legal requirements for all aspects of these traffic signs.

    I could say the same about advertisements of property, roads, computer monitors and so many other manufactured items. The units used to advertise them are not used to make or build them.

  39. Ezra Steinberg says:

    BBC seems to be all over the map. The nature shows I watch narrated by David Attenborough are mostly metric and in some cases entirely metric (even back in 2009, the earliest show I have watched with no Imperial whatsoever).

    If they could be consistent and 100% metric, that would be awesome!

  40. Daniel Jackson says:


    That all depends on the personal preference of the presenters and/or commentators. To be consistent the BBC has to either force the metric system on everyone or hire only personnel who prefer metric units to be consistent.

  41. Ezra Steinberg says:


    Honestly, the only thing I see the BBC forcing on everyone is a muddle. To me that seems like the worst of both worlds.

  42. Ezra Steinberg says:

    Since the original post here starts out by contrasting the metric measure of the intense rainfall in the UK on TV while the newspapers used Imperial, I thought I would poke around online and see how the Irish are providing weather info these days.

    The weather section of the Irish Times online is 100% metric, with the only slight oddity being the use of hPa instead of kPa for barometric pressure. The official weather site of the Irish weather service is also 100% metric. This makes me wonder if weather in the Irish Republic is always reported in Irish media purely in metric, no matter how hot the temperature or heavy the rainfall.


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