All too often, mystified when we measure

John Frewen-Lord recalls several recent examples of difficulties with measurement and asks if common measuring devices actually inhibit using the metric system.

It is said that constant exposure to the metric system (and its associated measuring devices) will gradually make us ever more comfortable in using the metric system on a day-to-day basis. But is this true?

When it comes to measuring devices, most of us have used the simple metric ruler, whether in school or at home. It is invariably easy to understand – a simple clear scale graduated in millimetres, with the 10-mm graduations marked off in some fashion. But does that simplicity and clarity apply to all the common of measuring devices we use or otherwise encounter in our (adult) daily lives? Not necessarily.

Some devices make it downright difficult to understand how to read them, while others actually invite you to not bother to measure in metric units at all, which no doubt pleases the metric sceptics in our society, but does nothing that actually benefits the country. Compounding all this is the fact that many people have a less than adequate understanding of the metric system itself, in spite of it being exclusively taught in schools for the last 40 years.

I noticed this recently when I went down to my local post office to post a parcel. I had already weighed it on my electronic kitchen scales, which displayed a reading of 482 g. Armed with this knowledge, I suggested to the lady behind the counter that we could see how accurate my kitchen scales were compared with the post office ones. “Probably not,” she replied. “Our scales measure only in kilograms.” Quite how she copes with grams and kilograms in her private life will remain a mystery.

More serious in terms of being able to measure in metric units was when a flying tree branch in a recent wind storm broke one of the windows of a nearby house. The tenant is a young man in his late 20s, who would have been educated at school entirely in metric. On being asked to assess the damage to the window, I phoned a window repair company, who asked me the size (in millimetres) of the sealed double-glazed unit in the hope that it might be a standard stock item. As I tried to manipulate the steel tape measure while still holding my phone, the tenant offered to measure the window. He gave me the dimensions in inches. I asked him for the dimensions in millimetres.

His response was that he didn’t actually know how to read a standard dual-marked steel tape in metric units – he could only do it in inches. And when you look at the typical steel tape available in the UK, perhaps his difficulty is partly understandable. For a start, and has been mentioned many times elsewhere both in the UK and in the USA, dual-marked steel tapes, which are the only type easily available, invariably have the imperial scale uppermost, which is the edge most people measure against. This applies even when the tape is labelled on its case in metres only (as many are, especially those intended for the building trade).

That in itself makes measuring off in metric units more difficult than it need be, but what makes things even more complicated is the number of different ways that metric units are displayed on various different tapes. My favourite tape is a surveyor’s 30-m metric-only tape that I bought in Germany.   It is marked off in millimetres (not centimetres) in 10-mm increments. Thus a measurement of 2163 mm would be measured or read off by going to the 2100 mark (in red, with the ‘2’ a larger size), then moving to the next 60 marking (in black), leaving you to just count off the final 3 millimetres.  It is very easy to read the right dimension, in millimetres, with no chance of error.

But the other steel tapes I have are much more confusing. They are all dual-marked, with the lower metric side using a variety of formats (centimetres only, separate metres and centimetres, but never just millimetres). No wonder people find it easier to use the upper imperial part of the tape. (Interestingly, I have an old wooden folding rule dating from the 1930s, given to me by my late uncle who was an engineer, and which, like my surveyor’s tape, is marked in just millimetres on the metric side, making it just as easy to read. Unusually the other side is marked off in decimal-feet.)

Other measuring devices might well also inhibit a true understanding of how to measure in metric units. The late Pat Naughtin extensively documented how dual tapes, thermometers, and so on retarded metric learning. While it is easy to buy a Celsius-only thermometer (my local garden centre sells nothing but), that seems to be about all. My electronic kitchen scales can be switched between imperial and metric, while my electronic bathroom scales can show three readings – kg, pounds, and the dreaded stones (and arrived originally set to stones, meaning that anyone wanting to use something else had to then find the switch and change the setting). Even my car can be switched between metric and imperial for nearly all its computerised functions (and arrived set to imperial, except for the climate control and outside temperature displays, which are Celsius-only, no doubt reflecting the fact that the British public really do appear to have embraced metric temperatures).

It seems to me that there is a decision on the part of manufacturers of measuring devices to make using metric measurements as difficult as possible, thus prolonging the unnecessary use of imperial in our mostly metric world. Can all this be changed? Technically of course, yes – manufacturers could easily make metric scales and markings much easier (and the default), as well as giving us a choice as to whether we want metric-only devices or dual-marked ones (after all, we have a choice in most other things we can buy). In practice, however, for some reason, such choice in measuring devices seems non-existent, and will probably stay that way unless either the British public starts demanding metric-only (or at least metric-friendly) measuring devices across the board (not very likely), or the government mandates some proper metric-only standards at the consumer level (even less likely). All part of our Very British Mess.

Editor’s note: Details of metric supplies, including measuring tapes, can be found at the UKMA web site: 

13 thoughts on “All too often, mystified when we measure”

  1. While I am no more than a metric-supporting bystander in this discussion, I don’t think you can lay all the blame at the door of equipment manufacturers for not making metric-only equipment. What the manufacturers of measuring equipment need is a clear sign from the government that metric really is the country’s national system of measurement for all purposes. Given that the metric system has been taught as the primary system of measurement for forty-odd years, it is amazing that this signal has not yet been given. Car manufacturers have obviously adapted to the reality of a mixture of metric and imperial units in the UK and simply pass the extra costs involved on to the buyer. I can clearly remember being told in the past that British cars are more expensive because they are built to a ‘higher British specification’. Of course they are not. They are simply more expensive to make because of the need to incorporate imperial units in the speedometer and display. And the same must surely be true of measuring equipment. The manufacturer makes what he or she thinks the market wants, or the government has decreed, and passes the extra costs of dual units on to the buyer. How often have I heard that kitchen equipment is so much cheaper on the Continent. Could it be something to do with the need to produce a more complex specification just for the UK market?


  2. A few years ago the Dutch chain of shops HEMA was bought by a British company. Then it started to sellkitchen scales with dual units, lb/oz and metric. The needle moved just over the metric readout, so that only the lb/oz readout was easy to read. I wonder, did HEMA want us to ditch metric in our kitchens? I haven’t seen these devices lately, thank goodness. Anyway, I would never buy dual measuring instruments. I bought a folding measuring rule, marked in mm ans cm only. Paradoxically we call those folding rules ‘duimstok’, translated ‘inch rule’!
    Inch rules without inches! Once I bought a thermometer and insisted to have a Celsius-only one. One exception: I would like to have a certified replica of a thermometer made by Fahrenheit and one by Celsius. I saw a few thermometers made by Fahrenheit in a museum in Leiden, and they were in good working order. They stood at 68 degrees, while the room thermostat showed 20 degrees Celsius.


  3. All this discussion leads back of course to the disadvantages to the UK economy of having a workforce that is not truly comfortable with mensuration in general and SI in particular. What a shame that this argument doesn’t seem to carry more weight with the present government!


  4. I’m always on the lookout for metric-only instruments. I have on occasion happened on some analogue kitchen scales that are metric-only and some measuring jugs.
    They are so much clearer and easier to read because of the lack of clutter, especially the measuring jugs.
    If people really are having trouble reading dual scales (I can quite believe they are) it is quite a serious matter. It must be causing a degree of incompetence and numerical illiteracy among UK citizens. When are the educators and politicians going to wake up to this?
    I am inclined to agree with Jake above that we can’t really blame the manufactures. If they think that metric-only markings will reduce demand for their goods they won’t make them. The change has to be lead from the top not left to market forces to do it for them.


  5. Article 4 of Directive 80/181 reads:

    “The use of units of measurement which are not or are no longer legal
    shall be authorized for:
    — products and equipment already on the market and/or in service on
    the date on which this Directive is adopted,
    — components and parts of products and of equipment necessary to
    supplement or replace components or parts of the above products
    and equipment.
    However, the use of legal units of measurement may be required for the
    indicators of measuring instruments.”

    I think this means that the UK Government could ban the manufacture, import and sale of dual unit measuring instruments – except that it could be argued that they are needed to service legacy imperial machinery and components. So it probably doesn’t amount to anything.

    As Jake says, the problem is that successive governments have failed to give a lead and have relied on the voluntary/gradual approach – which in practice means that the VBM will continue indefinitely until we have a Government prepared to take on the opposition and insist that imperial units are finally phased out. If only.


  6. But a government cannot really be better than the people “electing” it (often only by routine, conformism, etc. etc.): and if people don’t care so much about metrication (and maybe they also have other, much heavier problems), why should politicians care, then?

    Sadly, we don’t live in progressive times any more, where people – and governments inspired by them – direct the future……

    Just to be a little more clear: Australia, for example, could complete its formidable metrication in just a few years also and above all because the times were projected towards a future of common, worldwide prosperity and shared wealth: something that sadly isn’t the case, today, where everything and everyone rather incredibly tends to be self-referential – and thus think only about money and “power” (sic!), – yet another time.

    Well, if nothing else changes in the meantime, sadly probably the US and UK will really and fully metricate only when we will have a planetary society and government – and who knows when…


  7. It is not a question of the government being better than the people. It is about those in a position to bring about or encourage constructive change across society.

    For example, businesses won’t advertize and describe their products in metric only if they think it will put them at a disadvantage compared to those who use imperial. But, if the law required metric only it would solve the dilemma because they would then know everyone else has to do the same. Only governments can bring about that change in law and although it restricts what traders can do they would benefit from it.

    If the politicians were to point this out they might garner popular support for such a move. They don’t have to just bend with popular opinion they can and do influence it when they think it matters (q.v. the “no” campaign for Scottish independence).


  8. Well, maybe the question could be reformulated in this way, then: why don’t politicians care? why don’t people care? and why, finally, doesn’t society as a whole seem to care? about full metrication, of course, in this case.

    Evidently, there is some form of vicious circle preventing progress in this field (and also others, sadly): perhaps things like reciprocal distrust, ignorance, egoism, etc. etc.

    Anyway, there doesn’t seem to be much projection towards the future for ideals like metrication, while the so-called globalisation sadly seems to be mostly only in the economical-financial field.

    For the UK, the EU could certainly contribute towards accelerating a full metrication, if only it weren’t so bureaucratic and formal (and the British government too self-centered): but, again, if there isn’t a real “political” will to do so, what can one expect, then?

    (Personally, anyway, I think that people – the civil society of citizens – should count much more and governments less, but that’s of course only IMHO.)


  9. Here is another example of the confusion that dual (or, in this instance, imperial-only) measuring devices can create, this time with potentially serious consequences. I was behind a young mother at a coffee shop counter, who asked that her baby’s milk be heated to 50 degrees. The girl behind the counter replied that she could heat it to 120 degrees, and was that OK. The young mother, looking confused, agreed, but it was obvious she had no idea how hot 120 degrees was. I looked myself at the thermometers used by the coffee shop, and they were all in Fahrenheit (surely this should not be allowed). Luckily the two temperatures on this occasion were comparable, but it could have been catastrophic for the baby if a wrong conversion had been made.


  10. ITV news last night. Reporting the search for the missing Malaysian airliner (not a trivial matter), the Australian spokesman gave the current search area as ‘a 200 km square’ quite a sizeable area. The ITV translation into English, given so we could understand it, was shown in the caption as ‘123 sq miles’, which is about 18 km square! An all too common mistake.
    If the media people have no idea what they are talking about, and no idea of the difference between the sides of a square and its area, why do they consider themselves in a position to try to ‘educate’ their audience?


  11. The late Pat Naughtin said “don’t duel with dual” meaning that as long as the old Imperial measures are displayed, people will continue to use them, and fail to change to the new metric measures.
    Dual measuring tapes are prime example, of people continuing to use the familiar Imperial units.

    Why is it so difficult to purchase pure millimetre measuring tapes in the UK
    It’s not that tape manufactures don’t make them.

    It’s not difficult to purchase pure millimetre tapes in Australia or New Zealand.

    Stanley FatMax Xtreme 8 m Model number 33-894.
    Stanley FatMax Blade Armor 8 m Model number 33-732.
    Stanley LeverLock 8 m. Model number 30-528.

    These are pure millimetre tapes manufactured by Stanley.

    I am sure, there would be a market, as theses tapes are a “must have” for builders and construction workers.

    In a competitive business environment, is this a lost opportunity for tape manufacturers? Or is there some type of “metric embargo” which prevents the sale of pure millimetre tapes?


  12. @BrianAC I am assuming that you had a typo on the figure you quoted, as 123 sq miles equates to 318.57 km2.

    ITV should have realised that 200 km2 equates to 77.22 sq miles, not the 123 sq miles they actually quoted, perhaps it is time for them to employ someone who can use Google to work it out for them.


  13. 123 mile is actually 198 km.

    Brian’s point was that ITV converted a 200 km square (i.e. an area of 40 000 km2) to an area of ‘123 square miles’ rather than a 123 mile square (an area of 15 129 square miles).

    Hope that helps.

    In any case just another example of the confusion wrought by dual measures.


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