Our awkward, dual measuring instruments

As a consequence of the “very British mess” with measurement policy, the public has to put up with awkward, cluttered, hard-to-read dual measuring instruments. Various types are used every day. In this article, Ronnie Cohen describes several examples and comments on their impact on our daily lives.


Do you drive on British roads? If you do, you probably have to put up with a cluttered speedometer like the one shown above. The speedometer and odometer display miles to satisfy UK legal requirements despite the fact that modern cars are entirely designed, built and manufactured using metric units and so are British roads and all objects related to them. The only thing that is imperial on British roads are the units displayed on official road signs.


Do you cook or sometimes need to find out how hot the weather is? You will find it tough to find a thermometer or cooker that shows only Celsius. They predominantly show both Celsius and Fahrenheit, despite the fact that most modern recipes and weather reports are metric. It is a sad reflection of the continuing measurement mess Britons face in this country.


If you cook, the cluttered display on your cooker is not the only problem you face. You also face the messy displays on measuring jugs and kitchen scales. The measuring jug on the left (shown above) was on sale in a major UK department store and shows measurements in four volume measures. When the pint lines are compared with the millilitre lines, it is clear that UK pints are intended. However, take a look at the misaligned pint and fluid ounce lines. In the UK system, there are exactly 20 fluid ounces in a pint so you would expect the 1 pint and 20 fl oz lines to be perfectly aligned. However, they are not. This suggests that the fl oz lines represent the US fl oz of 29.6 mL rather than the UK fl oz of 28.4 mL but how many users of this jug would expect this to be the case? The jug also displays volume measures in cups. How many Britons know how big a cup is? What a confusing and messy mixture of measurements on a measuring device!


Do you work in construction, design, surveying or DIY work? The scale that most want to use on the pull-out measuring tape is on the bottom. The scale on the top is of no interest to construction industry professionals. If you try to use the metric units on the pull-out measuring tape for drawing lines, you have to use it in an awkward, cack-handed way with the units along the bottom. Likewise, a user of inches would have to use the steel ruler in an awkward, cack-handed way with the inches along the bottom. Obviously, it is much easier to use the top sides to draw lines. However, when both imperial and metric units are shown with increasing numbers written right-side up, either metric users or imperial users end up being the losers because one of these measurement systems must use the bottom side. When one set of numbers is shown upside-down with increasing numbers on one side and decreasing numbers on the other side, this makes the ruler look odd.


Do you buy loose fruit and vegetables at your local supermarket? The weighing scale shown above is used at a major British supermarket. Look at how crowded the display is, where grams and kilograms are outside the circle and where pounds and ounces are inside the circle. The major and minor lines around the circle look congested.


However, take a look at the weighing scale on a mobile staff trolley at the same supermarket and compare it to the one it provides to its customers. What a constrast! It is so much clearer and easier to read. It shows how much clearer single-unit measuring devices are compared to the dual-unit measuring devices. Unfortunately, measuring devices provided and sold to the general public are predominantly dual. Single-unit measuring devices on sale are hard to find.


Metric_Pull-out_Measuring_Tape_DrMetric (1)

These images of metric-only tapes show more examples of how much clearer, more user-friendly, easier-to-read single-unit measuring devices are compared to the dual-unit ones that are the norm in the UK.

As a consequence of the UK measurement mess, the availability of single-unit measuring devices is very limited so we are compelled to use awkward, cluttered, hard-to-read dual-unit measuring devices. This is the price we have to pay every day for the failure of the UK to complete its transition to the metric system and a sad reflection of the mess of two competing systems we find ourselves with today. The important lesson that British politicians must learn is don’t duel with dual. It’s not worth it.


(1) Reproduced with kind permission of Dr Metric. Source: p9 of “How Big is an Acre?” booklet by Alan Young (a.k.a. Dr Metric). Website: http://www.drmetric.com/

32 thoughts on “Our awkward, dual measuring instruments”

  1. I hate the clutter you describe, as it just makes measurement difficult and error-prone. I would rather use something that is purely imperial than something that shows both at the same time. However, as metric is simpler I seek out measurement equipment that is either metric only, or which can be switched to display metric only.

    I find dual-unit tape measures particularly awkward to use, so I’ve bought replacements from Germany. I did, however, manage to find a Celsius only jam thermometer on amazon.co.uk, which is just so much easier to use than the dual-unit versions. I don’t actually need the temperature in Celsius (or anything else), but losing one unnecessary scale frees up space for the all-important markers, such as the jam setting point.


  2. Regarding speedometers, speedometers in Canada are often dual-marked – with the km/h scale predominant, and the mph supplementary (for use when visiting south of the border). They are seen most often from North American (Ford, GM, Fiat-Chrysler), Japanese (Toyota, Nissan, Honda), and Korean (Hyundai, Kia) makers – the Europeans (Mercedes, BMW, Audi, Volvo) tend to use km/h-only markings. I did once own a 1990 Jeep Cherokee in Canada that had a metric-only speedometer, but that was an exception.

    The standard dual-marked tape that seems to be the only type available in the UK is a particular pet hate of mine. As a surveyor and construction professional, I find it the most awkward and time consuming bit of kit I have. Even at a trade-only builder’s supply shop where I have an account, they can only sell me a dual-marked tape. I had to go to Germany to get a metric-only steel tape. That has now broken after many years of use, so I will have to look on the internet to find a replacement. I do have a folding steel rule that is metric-only (both sides), and that is very useful. I believe it dates from the late 1940s! (I think my father may have got it when he was on the Berlin airlift, though there are no markings on it to say where it came from.)

    Some people will never change (and that is their prerogative). But for those that do want to move on into the 21st century world, it very unfair for manufacturers and retailers to thwart that goal in terms of providing metric-only measurement units, on the (supposed) basis that they are only giving what the public wants. SOME public, maybe, but not this member, and I know many others. Give us a choice at least.


  3. Update on my previous post. I had occasion today to go into my builders supply shop, and there on the counter was a box of 2-m long metric-only steel tapes! And for a mere £1 each. I asked the lady serving what prompted that, and she replied that so many people have been asking for such tapes that the shop finally decided to ‘test the market’. Now a 2-m long tape I would suggest is hardly testing the market, especially some 40 years (!) after the construction industry converted, but it does show that the demand is there – and likely more than is realised, since most people probably just assume that the dual marked tapes are the only ones available.

    I bought three of these tapes – always useful, and small enough to carry around in a pocket. I had a short conversation with the lady who served me, and she was very gung ho on finishing the conversion process – to use her words, “We were supposed to be metric only by now. A big pain for us in having to keep converting back to imperial because some people can’t be bothered to learn metric!” My sentiments entirely.


  4. Dual measures sound like a good idea – until you use them. Then they’re a pain in the neck.

    In Australia the speedos are always metric only, but for some reason dual tape measures are often cheaper than metric only measures. However, there is some limited use of the older measures for such things as screen sizes, and the hectare is only making slow headway against the acre in describing rural land. Why some measures should linger on when other measures are replaced completely is curious but puzzling.


  5. @John Frewen-Lord

    In point of fact, there are quite a number of metric only steel tapes available now. A search of ‘measuring tape metric only’ on Ebay alone brings up 162 listings, and they are not tapes with the top half missing!
    Be wary though of the ‘4 way’ tape which is upside down in all 4 ways! I bought one of these and had to return it at my own expense. The seller said they had sold over 1000 of these, (now at 2428 sold) and I was the only one to complain. I found that hard to believe. There are a couple of good rulers also.

    The customer scales in the local Tesco veggie department are now metric only, identical to the ‘DETECTO’ one shown above (they still post price/lb on the shelves though!) Not so good on their back to school rulers, they are still dual.


  6. Today I have found and bought metric-only, fibreglass tailors’ tapes.
    At last I can measure myself properly!


  7. Such devices are also foisted on us. Once I bought a thermometer and I insisted it should be Celsius only. The shopkeepet claimed that they did not have such a thermometer. I would not buy a dual Celsius/Fahrenheit one; but then they did have the device I wanted and I returned home with a Celsius only thermometer.
    A few years ago a shop named Hema, now under British ownership, sold kitchen scales in The Netherlands with oz-lb on the outside, metric on the inside, which made them almost unusable. It is beyond me why such scales should be sold in metric countries. On a forum I advised people to boycott such scales, as I stated that they were difficult to read if you wanted to use metric and that we have no use for ounces and pounds. I have not seen these scales lately in that shop.
    Once I was helping to build an exposition. Someone was measuring with a dual measuring tape and it looked as if he was measuring with inches. Then he realized he was attempting to read the inch size by mistake and turned the tape around immediately, completing the measurement in metric.
    I make an exception for old authentic measuring instruments. A friend wants to give me a thermometer from the beginning of the twentieth century in Fahrenheit and Reaumur, and I will accept it gladly because I like such historic items. But present-day thermometers, no way, only Celsius or Celsius – Kelvin are acceptable for me.


  8. John,

    I would be curious to know how her market test is going. They can sell more of the metric only tapes if they advertise they have them. Customers may assume they don’t exist, so they don’t look for them in the shops. Instead they wait until they make a trip to to the Continent or buy them via the internet. A loss for local shops.

    The local shops have to be the effective force to tell their suppliers that customers want metric only tapes. I’m sure they will be cheaper than dual tapes as Chinese suppliers have to make an extra effort to stick the English market with these, selling a massive amount of metric only on the Continent. Keeping that shipment separate comes at a cost.


    Any reason dual tapes are cheaper? Is it a quality issue? Are the metric tapes artificially set at a higher price to subsidise the dual tapes? Unlike England, Australia is a trapped Market. Australians can’t go to neighbouring foreign countries like the European Continent to buy what isn’t available in local shops. Do the trades buy their tapes from the local shops and thus suffer with dual or do they have a network of suppliers that bypass the shops and supply their workers with metric only? If the latter be the case, then the shops should take notice. They are being by-passed and losing business when they can profit from low cost metric tapes if they would only order them and sell them.


    I would never by anything from Ebay for the reason you mention. If you don’t like the product, it costs a lot to return it. It may be in reality that others bought the tapes, found them useless but don’t want to bother with the cost to return them. Thus sending a false message to the supplier that no one is complaining. This type of novelty may find itself sitting in a toolbox collecting dust.

    Good to see that dual customer scales are starting to vanish. As for the rulers, I’m sure they just sell what the distributor carries. You need to pressure them to provide metric only. It would be interesting to see what would happen if every shop sold both dual and metric only and which ones sold the most. Maybe the shops are afraid that if they did, they would discover the metric would sell out and the dual just sit there collecting dust.


  9. @Daniel
    “I would never by anything from Ebay for the reason you mention.”

    Off topic yes, but returning an item to a store 30 km (or even 5 km) away does not come cheap, and you cannot claim transport and parking costs back from the store. Some do it on-line, some drive, horses for courses.


  10. @Daniel:

    Went into the shop again today. There were quite a lot fewer 2-m tapes in the box today than there were last week. This time a man served me. I asked him if he had any longer metric-only steel tapes, but the answer was not at this time. Maybe in the future….


  11. Can’t read this without popping in a positive word for the wonderful Clas Ohlson. Some of their stock is generic dual-measurement stuff – but they sold at least two types of own-brand metric-only tape measure last time I was there and at very reasonable prices. The only snag is that it’s not clear which ones are which on their website and they only have a few stores in the UK. Worth popping in if you’re near one, though.


  12. I’ve just checked, and amazon.co.uk now sell metric only tape measures:


    I noticed that “metric only tape measures” is in the list of pre-defined searches. However, be warned that the search turns up dual measure tapes too.
    There are no issues returning anything to Amazon, should your chosen product not measure up to your expectations.


  13. John,

    You can always remind the shop keeper, that if they don’t have the metric products on their shops that you have an alternative to buy on-line or on your next trip to France. I’m sure they don’t want to hear that and will make an effort to bring in more metric only tapes.

    But they also need to advertise that they have them, especially to the trade groups.


  14. Daniel,

    I checked at a local hardware store and found that the metric only tape measures were the same price as the dual models. However, there were some cheap spirit levels with inches on them. I suspect that dual tape measures and spirit levels are remaindered and sold at a discount to get rid of them.


  15. Michael,

    It seems nonsensical that a shop would stock a product that it has to offer at a discount in order to get rid of it. So in effect the shop is losing money because the customer is buying the cheap useless product leaving the more expensive quality product going unsold.

    If the shop carried only the metric only quality product, customer would buy it out of need and the shops profits will rise. If the shops stopped buying the non-metric junk, the importers wouldn’t order them and factories would eventually stop making them.


  16. Slight correction: “The speedometer and odometer display miles to satisfy UK legal requirements”.
    There is no legal requirement for the odometer to display miles. Only the speedometer should be capable of displaying miles or kilometres – normally both are on display on UK vehicles but the regulations do allow for digital speed displays provided they can be switched between units.


  17. You didn’t mention tyre pressure gauges. Mine has 4 units I think. I don’t even know what some of the scales are. Needless to say, it’s almost impossible to work out what pressure you have in your tyres, which is a basic safety concern.


  18. When I was importing vehicles from Japan, I was compelled to convert the speedometer to Imperial measurement (miles per hour). A simple sticker would surely have been adequate, by I had to solder an electric element on the back of the speedo head, also disabling the speed restriction control (chipping).
    At the same, that green grocer was being hounded into an early grave for selling his bananas in imperial rather than metric measurement.
    Mishmash UK: Hate it and leave it.
    Jack, the Japan Alps Brit
    Currently wintering in warmer climes


  19. I’ve recently seen relatively new cars being sold with MPH only speedometers (I’m ignoring the fact that some may have digital displays capable of displaying km/h), I avoided buying a foot pump in Tesco that only displayed LB/SQ IN with no other units and am past the point of frustration at DIY stores still insisting on packaging things like wood screws in imperial-only packaging.


  20. Han Maenan wrote “But present-day thermometers, no way, only Celsius or Celsius – Kelvin are acceptable for me”. A few years ago I spotted a Celsius-Kelvin thermometer in the Grote of Sint-Stevenskerk, Nijmegen. Is anybody aware of any other Celsius-Kelvin thermometers that are publically visible?


  21. A bit of good news: a British journalist for The Guardian was being interviewed by an American host on TV about the COPS21 climate change conference in Paris. The American presenter had been using Fahrenheit followed by Celsius to describe the various temperature rise targets and redlines for climate change. She then asked the reporter from The Guardian about his impressions of the conference. In his reply the middle-aged reporter made reference to the 1.5 degree Celsius target adopted by the conference and then added “Sorry, I don’t do Fahrenheit”.

    From the way he said it I took it to mean he didn’t understand Fahrenheit and didn’t know how to convert from Celsius to Fahrenheit. Finally! It seems like Fahrenheit has pretty much gone the way of the dodo in the UK.

    Reminds of a Canadian co-worker who had come down to work in the States. When I talked to him about temperature, he confessed that he had not yet gotten the hang of Fahrenheit even after living several years in the States. “I really only understand Celsius.” he told me.

    I heard something similar on the radio when an American presenter was interviewing someone in New Brunswick. The Canadian referred to a particular temperature in degrees Celsius, then apologized by saying she was sorry she didn’t understand Fahrenheit at all.

    Yes, Virginia, there is hope! 🙂


  22. Seem Vauxhall use “mls” as an abbreviation for miles (mi).
    Mishmash UK: not exactly chaos, for to have chaos you must first have order. More a mess.


  23. Indeed, that is a marvelous philosophy you espouse: Willful ignorance of a system still in common use.

    With the recent cold weather, it seems that B.B.C. has tweeted several times in both Fahrenheit and Celsius. It must be quite difficult in the summer ascertaining the temperature with a willful ignorance of the Fahrenheit scale!


  24. It is good to see that not teaching imperial in the schools in either Canada nor the UK is having a profound effect. This is really excellent news going into the new year. It also dispels the nonsensical rhetoric of metric opposition groups that imperial is still in common use.

    It is great joy when people in English speaking countries really don’t know either imperial nor USC. We can only hope this trend continues. We can also thank those teachers in the UK and elsewhere who do the right thing by not teaching that which will just add confusion to everyone’s life and make them unfit for modern jobs.

    Now let’s work on getting those road signs changed. We already have gotten through the door with height and width signs being added in metric. Next we need to get the rest of signs changed over. Full metrication by 2020 must be our goal.


  25. @ Active Resistance to Metrication says:2015-12-30 at 00:45
    Indeed, that is a marvelous philosophy you espouse: Willful ignorance of a system still in common use.

    Indeed it is. The general idea is to stop using the non-system, that is the whole point! There is no need for a mixed muddle of measures alongside the integrated system used throughout the world.
    I do wonder how you think the rest of the world manage without feet and inches, it must be real hard for them. Willful ignorance my foot.

    Now to this recent cold weather. I do not know which country you are in, but UK has just had one of the warmest Decembers on record, albeit a bit on the wet side. Here is the search info for 31st December 2015, 21:30 hrs, should you doubt me: –
    Warmest December on record and second wettest in more than 100 years. ITV News? – 7 hours ago
    This December has being the warmest on record, according to latest figures from the Met …
    Record lack of frost in England and Wales during warmest December ever Telegraph.co.uk? – 1 hour ago
    This has been the warmest December ever in the UK – and one of the wettest The Independent? – 5 hours ago
    More news for warmest december

    You say the BBC ‘seems’ to have tweeted … . Well, I personally am not into tweeting, but I do follow the news and weather. In recent months there has been very little of that F word on BBC, none at all that I have heard on the national channel. On our local channel there is one, and one only, weekend weather reader that does slip in that F word. If not for that, the F word would be totally dead. Again I find it difficult to understand your point.
    You really are stretching the point if you think (or can convince us that you think) that we will be somehow be lost in a sea of confusion over temperature come the summer. This summer gone, even the red tops hardly used the F at all. You leave me totally confused as to what you are thinking of. Fahrenheit is all but dead and buried in UK. I will stick with the safe bet of the Celsius scale TYVM.
    Whatever the media use, the Met Office uses degrees C and millimetres, that is where all the reports originate from.


  26. Happy new year to one and all.
    It is only the first of January and already it is the coldest night of the year.
    4.5 degrees Celsius, or errm, (32 + (4.5*9/5)) degrees Fahrenheit (I think).


  27. @ ARM

    Ascertaining the temperature? I simply read the temperature off my Celsius thermometer. I don’t have to ‘ascertain’ anything. Summer and winter. It’s easy if you try.


  28. Celsius has been in common use for decades and the only reason for Fahrenheit conversions in UK broadcasting is to cater for the wilfully ignorant.


  29. @ARM
    Since at least the 1960s, BBC TV weather forecasts have always shown maps with temperatures only in degrees Celsius.

    It doesn’t take much to willfully ignore Fahrenheit.


  30. I think the nonsense of using multiple scales for temperature was neatly illustrated by the story in the independent http://www.independent.co.uk/news/science/storm-frank-freak-weather-uk-north-pole-40-50-degrees-hotter-than-normal-a6789916.html reporting that the temperature at the North Pole would be 50°F above its normal. Many comments had translated 50°F as 10°C and said why couldn’t they report it as that value. The problem is that although 50°F is 10°C, the zero on the scale is in a different place. So a temperature difference of 50°F is actually a temperature difference of 30°C.

    Why would you want that degree of complexity in a report that simply says “it’s going to be 0 instead of 30 at the North Pole.”? Using different scales is a problem for understanding.


  31. I stated in a message above that a friend would give me an old thermometer with Fahrenheit and Reaumur. I got it recently: it was made in London in the beginning of the 20th century, a nice authentic device. I compared the scales on the thermometer and concluded that it carries Fahrenheit and Celsius, not Fahrenheit and Reaumur.


  32. The so-called Metric Tape measuring devices, which are shown on this site, are delusional in that they are NOT calibrated in millimetres and are. therefore, almost as useless as “dual measuring tapes”.

    Don’t “Duel with Dual.”

    Please look at http://themetricmaven.com/?p=411, wherein it is discussed that there is (in the USA) an “Invisible Metric Embargo,” produced by so called “Metric” measuring tapes which do NOT have the Millimetre as the basic unit for their measurements.

    PLEASE, change those illustrations to show only measuring tapes calibrated in Millimetres.

    Note that “US “METRIC DESIGN GUIDE (PBS-PQ260) September 1995”
    http://www.gsa.gov/graphics/pbs/Metric_Design_Guide_R2E-c-oW_0Z5RDZ-i34K-pR.pdf states : –

    Centimeters are typically not used in U.S. specifications. This is consistent with the recommendations of AIA and the American Society of Testing Materials (ASTM). Centimeters are not used in major codes.

    Also, note that, in Australia, the Australian Building and Construction Advisory Committee policy was:
    The metric units for linear measurement in building and construction will be the metre (m) and the millimetre (mm), with the kilometre (km) being used where required. This will apply to all sectors of the industry, and the centimetre (cm) shall not be used. … the centimetre should not be used in any calculation and it should never be written down. (Standards Association of Australia “Metric Handbook, Metric Conversion in Building and Construction” 1972)


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