Goodbye Imperial. Hello British weights and measures

We, the public, are encouraged by some politicians, by the DfT and by elements of the media to pick and mix our measurement units – to use both imperial and metric. So why has imperial as a system fallen from favour among those resisting change, and been replaced by a hybrid?

Because, in short, it has been become unfit for purpose.

The imperial system and its US counterpart stopped developing about 200 years ago. They do not contain units to measure more recent discoveries such as electricity or radiation. For example, if you try to find the imperial unit of electrical current, you will be disappointed. So anyone living today will not know a time when only imperial units were used.

The imperial system has a limited range of size of units and is unsuitable for measuring the extremely large and the extremely small. For example, the chemical composition of a bottle of mineral water and the dosage of modern medicines are measured in milligrams, never in imperial. The imperial system’s smallest unit of mass is the grain, which is equivalent to approximately 65 mg. Imperial units of mass do not cover a sufficient range for such tiny quantities so it is no surprise that you never see any imperial conversions for them. Similarly, it is not useful for describing scientific concepts such as the size of atoms and the wavelengths of light. At the other end of the scale, the imperial system struggles with distances in space, the mass of planets or the power output of stars. The resulting strings of zeros can be difficult to comprehend.

But there must be other reasons why many of us can not be bothered with imperial’s quirky complexities.

For forty years, children have learned metric at school. Could it be that as adults we are now comfortable with metric measures and try to apply the simplicity and logical nature of metric to the imperial measures we encounter, not always by choice, from day to day?

Imperial has frequently, for example, several names for the same physical quantity. For volume, there are the imperial and US dry and liquid measures. Quantities in these systems are different, even for units that share the same names. Common unit names that represent different quantities create ambiguity and obscure simple direct comparisons. So the litre gradually supplants its imperial rivals in day to day activities.

On the other hand, some imperial units for measurement have limited applications. For example, British thermal units are not suitable for measuring food energy intake, nor are pounds per square inch suitable for barometric pressure in weather reports. Fortunately, there are metric alternatives in common use.

Furthermore, some imperial unit names have different meanings, depending on where they are used. For example, when miles are used on land, we think of the statute mile but when miles are used at sea or in aviation it is the nautical mile. In all cases, the word “mile” is used and it is assumed that the type of mile is implicitly understood. The barrel also varies in size, depending on the commodity being measured. Pounds and ounces have different meanings for grocers and jewellers. All interesting for the professionals, but perhaps confusing for the person in the street.

And so, the use of the imperial system fades away. Our collection of medieval measures, which was overhauled in the 1820s to meet the needs of Britain’s industrial revolution, is seen as no longer fit for purpose. That is why those who would like the UK to have its own unique traditional measurement system, and their friends among politicians and the media, now favour the use of a hybrid of imperial and metric which they have called “British weights and measures”. Traditionalists will be relieved that the horsepower is likely to be around for a while, but may regret that the foot-candle is almost forgotten.

28 thoughts on “Goodbye Imperial. Hello British weights and measures”

  1. Hi Ronniec and all,
    We in the United States of America try very hard to keep our units of measure to cover industry, commerce, and the sciences. Many traditional units are now defined by SI units such as the mill, 1000th of an inch, equal to 2.54cm or is it 2.45? May be the UK can adopt US Customary units. 🙂


  2. Ed, thats just crazy. In the UK we know what a millimetre is, use it constantly in engineering and science, and don’t need a bastardised version of an old measurement imported from the US. In this day of international co-operation in many major projects, why do the US insist on sticking to old measurements? is it just to stop the rest of the world being bothered to bid for US military contracts?


  3. There can be little doubt that the protracted period of change and indecisiveness has led to the ludicrous and incompetent handling of measurement so aptly described in the article. Politicians and civil servants have forgotten or are simply not aware of the purpose of the change or the intended outcome, initiated so long ago.

    For them, as with the public, the measurement muddle is normal. Like people who are born with a disability they don’t know any different and learn to compensate.

    However, in this case the disability is curable. The sad thing is that it takes some pursuading that the impediment exists and the unnecessary burden it imposes.


  4. If you want an example of imperial’s quirky complexities, then measurement of area is a good starting point.

    Begin with an imperial linear measurement, the pole aka the rod or perch, equal to 5.5 yards (forgive the decimals – they make the arithmetic easier). This pole should not be confused with another pole, the square pole, equal to a linear pole squared or 30.25 square yards. Now there are 16 poles (the square variety) in a square chain (similar to avoirdupois ounces and pounds), and 10 (yes ten) square chains to an acre, so that means 160 poles per acre. Not forgetting the rood (which should not to be confused with the aforementioned rod), equal to a quarter of an acre or 40 poles. Simples.

    It is no wonder that the DfT, the most influential proponent of old measures in the UK, has given up on this lot. I suspect also that, among these measures of area, only the acre of has been given the accolade of inclusion in ‘British weights and measures’.


  5. When people are changing from one system to another it is quite normal to mix and match units. In Australia, for instance, personal weights changed to kilograms long ago while heights are still quoted in both feet and inches and centimetres in conversation but not in official or sporting information. It’s similar with distances. Miles gave way to kilometres long ago, but for shorter distances, while metres are taking over, inches, feet and yards are still encountered in conversation.

    I think the same thing is also happening in the UK. Fahrenheit is giving way to Celsius and hectares are gradually displacing acres. Even with personal heights and weights, some of the sporting teams are giving the information in metric measurements, so progress is being made on that front, too.


  6. Oh you are so right Wilfred. I have mentioned on here before the people I encounter at my work in a shop. Customers asks for measurements of an item, and of course I give it in metric e.g. 160cm. They will sometimes then say ‘whats that in old money’ so I will say 5’4 and usually get the reply ‘whats that in inches’!

    I also make the point that no new Imperial measurements have been introduced for at least 100 years, and that all modern technology from the invention of the automobile onwards use units that are metric. Camera lenses, films size, data transmission, processor speeds, memory capacity.

    I was listening to a BBC programme the other night at about 10pm that was telling the story of ‘Workers Playtime’, that was broadcast from the 1940s onwards I believe. The clip they played from that period had a BBC announcer telling listeners that they were ‘tuned to the Light Programme on 330 metres and 908 kHz’. This just reinforced it all for me. We have been metric for many many years in most aspects of our daily life. We just need the Government to see sense and get the message that more and more people are happy with metric and the time has come to complete the transition by removing references on road signs.

    I do hope that the focus on the need to improve numeracy, as well as the need to improve our manufacturing and skills base will convince them that now may be a right time to do this.


  7. @Michael Glass it’s interesting you mentioning Australia, I have two friends who’ve moved there in recent years and while one has become very metric (with the occasional lapse) the other posted the following comment on Facebook on Friday:

    “weatherman says we should expect somewhere between 4 inches to a foot of rain in the next 24 hours.”

    It seems strange to me that he would take the time to convert a metric weather forecast in that way so what was actually said? Is the American influence that we struggle with having an effect on Australia too?


  8. Hi Alex

    I have a Facebook Friend in Sweden, a totally metric country. He is a keen amateur meteorologist and has lots of friends in the US, and so he always targets his comments at them by using degrees F. I’m not sure he would know how to do the mm to inches conversion. But maybe your friend knows that a lot of the folks in the UK expect to hear imperial measurements (think of all those birth announcements) and so is converting on that basis?


  9. @Alex Bailey

    Googling, I found a site that gives Australian weather by city/region. I randomly picked Darwin, but it looks pretty completely metric:

    The page appears to be a script, every city follows the same format but local details plug into the spaces.


  10. Hi Alex,

    I’m surprised that anyone would say that an Australian weatherman would mention inches of rain. It’s all in millimetres, now. Chances are the weatherman said that there would be between 100 and 300mm of rain and your friend just changed it into inches for the sake of his American friends.

    But Australia is not the completely metric nirvana that some people fondly believe it might be. Inches linger on in the diagonal measurement of screen sizes from little mobile phones to giant flat screen televisions, though for the TV screens it shares the space with centimetres. And feet are still used by balloonists and other aircraft. Acres also linger in country areas, even though hectares are replacing them. But for most other things it’s metric all the way, especially for the young.


  11. Interesting to note Michael that the Australian exceptions you mention coincide with world-wide tendencies, probably due to US dominance in the past. Aviation use feet by international agreement, and display screen sizes are overwhelmingly in inches in Europe and probably elsewhere.

    If the US were to make the big push non-metric would die out globally.


  12. Living in a metric country, The Netherlands, I saw how the inch came in for screens (and computer disks) when the home computer made its debut. I suspect that it was an anti-metric global marketing campaign. In that time computer shops were also stacked high with packs of 11 and 12 inch paper, threatening to undo the international paper-sizes. The inch paper sizes disappeared when the inkjet replaced the dot matrix printer. When I bought an ink jet I immediately reverted to A4 from 12 inch. I could not use A4 on my old dot matrix printer.
    Manufacturers of air conditioning equipment are also at it. Full of glee, the former German Euro-commissioner Verheugen, wrote in an anti-SI text in 2009 that these manufacturers were replacing the kW with the BTU/h. He makes me think of Napoleon; he saw in the SI nothing but a cost causing entity and thus he proposed as many derogations on its use as possible. As I see, it, the BWMA could nominate Verheugen as an honorary member. The enemies of SI are still very dangerous.


  13. It is one thing to ‘pick’n’mix units, but the whole problem is that different people pick different units to mix their own language and no one else knows what they mean. It has seemed to me this is just fine as few people seem to understand measurements anyway. A grand niece of mine recently proudly posted on facebook the weight of her little sister as ‘6.15lb’, I doubt if she has any idea what her mummy meant when she was told it weighed 6lb 15oz., but that don’t seem to matter. If I know I have the ear of a metric sceptic or worse I will measure something like 2m and 2 inches just to take the mick. On a more serious note, I loathe and detest the universal use of inches for all forms of video display, despite cameras and film being mostly mm from day one. Even in France TV’s started to be displayed in ‘pouces’ (inches) soon after the EU gave up on metricating the UK. Interesting comment though from Ed the Yank on UK adopting US customary units, well, they are!! All our old 5l cans of liquids are now 4l cans, i.e. American gallons. Dual calibrated torque wrenches are now supplemented with the American inch pounds rather than the British foot pounds of the last 100 years and recently I have seen kitchen measuring jugs with the American 16 fl oz to the pint instead of the UK 20 fl oz to the pint. So there you are BWMA, out with metric, in with US measures, well done, we love you really. I look forward to the day black mains wires go from being neutral (UK standard) to live (American standard) could be fun.


  14. It’s true, that when people are changing from Imperial measures to Metric measures, there will be a hybrid period of mixed measures. Mixed measures meaning, for example, using centimetres for short measurements (less than a metre), and miles for long distances. People don’t generally become familiar with the new system as a whole. They learn in parts, and it depends on their exposure to the measures. For example, someone who shops becomes familiar with kilograms, but if they are not a road user they won’t be familiar with kilometre distances.

    In my opinion the UK hybrid situation is undesirable, and has occurred because of 2 main reasons:
    1…Dual labeling, dual tape measures etc, have made the process voluntary.
    2…Political interference in the process has made the process very slow, and it’s still not complete.
    Here in New Zealand, we had very little dual labeling, no political interference, and a supportive media, which meant that for most people the learning curve occurred over a period of about 2 to 3 years.

    Momentum is slowly building for change in the UK but it will require political will and leadership.


  15. WJG:

    Congrats to NZ for having done such a good job of converting to metric!

    Just curious … now that it’s been many years since the conversion, what evidence is there of Imperial hold-overs in New Zealand in 2012 whether in the workplace, in the media, or in everyday conversation? And are there any patterns as to who (age groups, social groups, etc.) or where in the economy these hold-overs persist?


  16. One of the quirks of human nature of course is to, in general, resist change. But the level of resistance is not, I believe, a straight line – it rises and falls in waves.

    In the period of, say, from the mid-1950s to the mid-1970s, the UK (as well as much of the world) seemed much more open to change than today. The ’50s and ’60s saw the explosion in rock-and-roll and pop music; cars changed from recycled pre-war models to new ‘tin boxes’ (as my father used to call them); the ’60s and ’70s saw new styles of architecture (and the now regretted demolition of some notable structures in their wake); and of course the formal decision for the UK to convert to SI. At the time, I seem to remember we actually embraced this change – I remember my mother (on a visit to the UK in the early 1970s – I was now living in Canada) being quite happy at using millilitres – em-ells, she called them. It was indeed a brave new world.

    But then, it seems a long period of resistance to all those changes occurred, mostly in the late-1980s, the 1990s and beyond. As well as resistance to the use of the metric system, we had Prince Charles ranting against modern architecture, traders were actively opposed to ‘the common market’ (it meant of course that they had to change the way they did business), buildings became ‘listed’ by the million, and so on.

    Today, perhaps we on the cusp of a new wave of change. Many new buildings now dot London’s skyline (including the tallest yet). British companies, small and large, compete with the best in the world (Rolls-Royce for one). The realisation is starting to register that, if the UK is to maintain its standard of living, it is going to HAVE to change the way it does things if it is to compete with the rest of the world, especially the far east, where they no longer have to look to the old world for technology transfer – they can now develop their own new technology, thank you very much.

    With this realisation that change must occur, is it too much to hope that a new generation of British young people – many from a multicultural background – will usurp the ‘old guard’ and finally end the silliness of trying to retain two sets of measurement units, and that one of them – the old Imperial one – must finally go? One can but hope!


  17. Metrication as part of multiculturalism and the erosion of national distinctions? Throwing out Imperial as part of ‘getting with the programme’ of becoming yet another member among many of the ‘global village’? Thank you, Mr. Frewen-Lord, you’ve just convinced me of the rightness of the anti-metric cause.

    I’m 34 years old but I don’t want to see Britain and Britishness melt in the multiculturalist pot. Use metric if that’s what best suits your purpose, but don’t foist it on an unwilling nation.


  18. @Aetheling
    I discovered when I first visited Denmark, over fifty years ago, that the Danes use metric measures. This does not appear to make them any less Danish. And when I visited Australia in 2006, I observed that Australians had taken to metric measures with enthusiasm and without obvious difficulties. This does not seem to have made them any less Australian. So why does using metric have to make the English any less English?
    BTW, a Danish King, Canute, ruled both England and Denmark in the eleventh century and is buried at Winchester.


  19. I am interested that Aetheling in Suffolk fears that metrication erodes Britishness. In fact, one of the glories of Britain, the English language, gets a lot of its power from its adoption of so many words from all over the world. The British are no less British because they use lb as a symbol for the pound weight, even though it is the abbreviation of a Latin word. Nor are they any less British because they measure roads in miles, even though the very word comes from the Latin and means a thousand double paces.

    The British are no less British because they use a Latin alphabet and Arabic numerals, adopted printing from Germany and use personal computers that were often designed in the United States and manufactured in China or Korea. And when they sit at the table (French word), eat off china plates, believe in a religion that originated in the Near East they are no less British than the Druids.

    Nor are the British any less British because they buy petrol in litres or weigh groceries in grams and kilograms and pay for these items in a decimalised currency. As for temperatures, whether you measure them in Fahrenheit or Celsius, you are using a system that was devised somewhere else.

    In time I believe that metric measures will become universal, like the Arabic numerals, the way we measure time and the way we write music. But despite a common notation for music, English music still remains distinctive.

    But why change the measures? Because the metric system is better than the alternative jumble of measures. And that is why it has been adopted by most of the world.


  20. I would like to add to the comments directed at Aetheling in Suffolk with regard to Britishness.

    The British Isles have always been a target for invasion, the fact the last one happened nearly 1000 years ago tends to hide the fact that much of what we define as “British” is actually imported by those invaders wether it be the French in 1066 who are probably responsible for much of our current language and way of life, the Romans who seem to be responsible for the way much of our infrastructure has developed… add in the influence of Germanic and Scandinavian invaders in the last 2-3 thousand years and you start to realise that what we refer to as “British” is really something that has been invented in the last century.

    So many of the things that are held up to define “Britishness” are actually imports… such as chips coming from the potato that was brought to us from South America, our royal family who’s current members are predominantly of German descent, and as mentioned elsewhere our “British system of measures” is actually a hotchpotch of things taken from other cultures (particularly the Romans) and even they often differ in use and definition to those used even in the last few centuries!

    It often seems to me that since the Second World War and the loss of it’s empire (and more so in the last couple of decades), that Britain as a whole seems hell bent on defining itself as something specific and different to the rest of the world, so much so that as a nation we’re losing the ability to change and evolve, to embrace ideas that come from other parts of the world (or, indeed, our own people in many cases) merely because “it dilutes our culture”.

    If our culture depends on trying to retain a vision of a nation stuck in the 1950’s then to be honest that culture needs to be consigned to the dustbin… if our culture is a symbol of a progressive Britain in a modern world then we need to be embracing change, not for the sake of change, but because it will be good for us. Metrication is a good example of that.


  21. @Ezra Steinberg

    I don’t want to go to far off topic. So I will try to keep my response brief.

    Present day Imperial hold overs in New Zealand.

    Weather forecasts (Marine only): Wind speed, knots; Visibility, Nautical Mile
    Groceries: Imported US packaged foodstuffs, for example, Californian Grape juice US customary sizes and dual labeling (US customary/Metric). However US imported foodstuffs are not very common.
    Education: Children are taught some knowledge of Imperial units mainly as conversions.
    Media: US TV programmes, US movies, and one or two UK TV programmes (eg Top Gear)
    Cars: Wheel diameter (inches) and tyres mixed measure (width metric, inside diameter inches); tyre air pressure (pounds per square inch) although some gauges are dual (psi/kPa). This is one area where we have not fully metricated.
    Dual Units: Cheap dual tape measures and thermometers from Two Dollar shops (ie Pound shops). These are imported from China and probably made for the US market as well. Electronic weighing scales for kitchen and bathroom are now dual unit.
    Body measurements: Sports and Medical organizations measure and record body height (metres), body weight (kilograms) and body waist (centimetres) in metric. New born babies are measured and recorded in grams.
    However because some older people find it difficult to grasp metric units, conversions to Imperial are available.
    Older people accept the metric enviroment around them, but the last bastion is their own body measurements which some prefer as Imperial units. I believe that these measurements are the last to change to metric.

    I hope this answers most of your questions.


  22. Dear Aetheling

    You wrote:
    “Use metric if that’s what best suits your purpose, but don’t foist it on an unwilling nation”

    If only it were that simple. That “unwilling nation” you talk about cannot make up its mind when to use imperial and when to use metric – not that it’s wise to mix them in any case.

    British society, like any other, needs a single system of measurement that everyone can understand and use. It has nothing to do with multiculteralism or trying to be like everyone else just for the sake of it. It’s a simple practical issue.

    You do what you like at a personal level but don’t fool yourself into thinking that you speak for the whole nation.


  23. I would like to raise a question on the selling of milk by the pint in supermarkets (in my case Tesco, I have no issue with them).
    Comments here indicate milk can be sold in pints in returnable bottles. Does that mean that supermarkets should not be selling by the pint (or two pints in this case) in non returnable containers? Or that I can take the container back and ask them to refill it? It seems stupid to see all the milk in liters, except the ordinary cows milk which is in 2 pints, 1.136 liter. My guess is that this makes 1 liter ‘special milks’ look cheaper against 1.136 liter of cows milk.


  24. @BrianAC

    This is an issue of ‘hard’ metric packaging (1 L, 2 L, etc) versus ‘soft’ (1.136 L, etc).

    There are now few legal requirements for ‘hard’ metric packaging in the UK, and certainly not for milk. The use of the pint for supply of milk in returnable containers is optional – your milkman can use 500 mL or any other amount if he wishes. However, all milk packaging except the pint in the so-called returnable container has to be labelled with the metric amount, with imperial as an optional supplementary.

    The prevalence of ‘hard’ metric packaging of fresh pasteurised milk in corner shops and ‘soft’ in supermarkets is a mystery to me. The British Retail Consortium, of which the major supermarkets are members, may be encouraging a united front.


  25. The thing that is odd about Tesco’s, Sainsbury’s and Co-op’s milk is the inconsistency even on their own shelves. Own-brand milk from these supermarkets tends to be packaged in multiples of 568 mL but dairy-branded milk on the same shelves is (mostly) in sensible multiples of litres. The trouble is, a 2 pint bottle and a 1 litre bottle look pretty much the same, and you don’t know what you’re buying until you read the label – which is usually on the back or the side of the container. And you can’t compare prices unless you can find the relevant “unit-price” labels on the shelves. There are often misaligned with the products themselves, so it call all be a right pain in the arse.

    Things are much better in Spar, Costcutter, Best-One and many other smaller outlet chains where the own-brand milk is as rationally packed as the dairy-brands.

    One Welsh dairy that I’ve seen buck the trend with the unique situation of selling milk in a progression of 1 pint, 1 litre, 2 litre bottles! That one really does take the biscuit!


  26. I mentioned the word ‘confused’ in a recent post.
    Today I was browsing for a metric only tape measure and came across the “Stanley 30-405”, 8m/26′ metric only tape.
    Now confused.Brian would like to know why a metric only tape would be labled by the manufacturer as a 8m/26′ tape.
    Here is a good photo from Tesco direct

    To be fair, I did search in more detail and it now seems to be ‘unavailable’ from most stockists, I wonder why?


  27. @Brian AC

    Actually it’s worse than you reported. If you study the picture you will see that, although the tape is apparently metric only, the calibrations are only on the BOTTOM edge of the tape (if you hold it the right way up, with the start on the left). This makes it slightly more difficult to measure and mark accurately as you would normally take your reading from the top of the tape (unless you turn it upside down with the start on the right).

    The standard Stanley tapes are of course dual metric/imperial, with imperial on top. So all Stanley have done is produce their standard tape with the upper markings omitted. There has been no attempt to produce a tape to the requirements of the user. No wonder nobody stocks it. They will probably conclude that there is no demand for metric-only tapes and stop making them!

    UKMA’s website gives some advice at Or buy your supplies while on the Continent. In France the big hypermarkets stock them – also kitchen and bathroom scales, although even these sometimes are switchable.


  28. @BrianAC

    Stanley manufacture the following metric only, 8 m measuring tapes.

    Stanley Fat Max 8 m Part number 33 732.
    Stanley Max 8 m Part number 33 966
    Stanley Leverlock 8 m Part number 30 528

    These are readily available in both Australia and New Zealand.

    I recommend the 30 528. I have one myself. It’s a true millimetre tape. After looking at various UK Internet sites, it seems as if its difficult, to source metric tapes, that are true millimetre tapes. Most are centimetre/millimetre hybrid tapes, in that, although the markings are millimetres, the numbers are centimetres. Millimetres are “King” here and most people only use centimetres to measure their height.
    I hope this is of some assistance.


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