First metrication reversal since Napoleon?

If the current Government implement their proposals to remove the requirement to use metric units for trade, it will be the first reversal of metrication in the UK and probably the first reversal in Europe since the days of Napoleon over 200 years ago.

France was the first country to introduce the metric system to replace a bewildering number of different measurement systems used across the country. They introduced it during the French Revolution in the late eighteenth century. This was accompanied by a public education campaign to familiarise the general public with the new measurements. The French Emperor Napoleon saw the metric system as an inconvenience and the populace continued to use the old measurements. For these reasons, Napoleon issued the imperial decree of 12 February 1812. He introduced the mesures usuelles (customary measures) where old units were redefined with rational metric sizes.

Under the mesures usuelles, the following units were redefined as follows:

  • toise (fathom) = exactly 2 metres
  • aune (ell) = exactly 120 centimetres
  • boisseau (bushel) = exactly an eighth of a hectolitre
  • livre (pound) = exactly 500 grams

In the mesures usuelles system, these newly defined units plus the litre, the metric unit we are all familiar with, were divided as follows:

  • The toise (fathom) was divided into 6 pieds (feet) and 72 pouces (inches). The pouce was divided into 12 lignes (lines).
  • The aune (ell) was divided into the demi aune (half an ell) and the tiers aune (third of an ell).
  • The litre was divided into demis (halves), quarts (quarters or fourths), huitièmes (eighths) and seizièmes (sixteenths).
  • The boisseau (bushel) was divided into the double-boisseau (double bushel), demi-boisseau (half bushel) and quart-boisseau (quarter bushel).
  • The livre (pound) was divided into 16 onces (ounces), each once was divided into 8 gros and each gros was divided into 72 grains (grains).

Ever since the Weights and Measures (Metric System) Act legalised metric measures for ‘contracts and dealings’ in 1864, the UK has never gone backward on metrication. The UK has made erratic progress on metrication, sometimes making a lot of progress, such as the 1960’s and 1970’s after the start of the UK Metrication Programme in 1965, and making little or no progress at other times, for example, since the year 2000.

It is hard to think of other reversals of metrication because they are rare. John Frewen-Lord has commented on Canada’s reversal of metrication under huge pressure from the USA when Brian Mulroney was Prime Minister of Canada. You can read his comments in these past MV articles:

The outcome of these measures was to make Canada’s unsatisfactory situation worse. Like the UK, Canada is still in a measurement muddle. It is not an example to follow nor is Napoleon’s imperial decree of mesures usuelles.

If the Government is looking at mesures usuelles as an important precedent, they will be disappointed to learn that the reversal of metrication was not permanent and ended in one generation. Twenty-five years after Napoleon’s imperial decree, King Louis Philippe I revoked the use of traditional and customary measures by the law of 4 July 1837. This came into force in 1 January 1840 and the metric system was fully reinstated. This ended the use of mesures usuelles.


23 thoughts on “First metrication reversal since Napoleon?”

  1. I often wonder if it would help if there was a mesures usuelles for the anglosphere. Not official along the lines of Napolean, but unofficial for the sake of those Luddites who can’t or won’t learn SI and move forward. For centuries, the various pounds in Europe were standardised as 500 g. All of the scales were legally only in grams. No issue with the masses as they could still ask for a pound or half-pound and they would have 500 g or 250 g measured out on the scale or balance.

    In England and maybe also elsewhere, the pound is an odd 453.592 370 g often rounded to 454 g. It has to be a mess to convert this as well a confusing expense to businesses that fill jars and cans to metric sizes in increments of 5 g or 5 mL for liquids. How much more sense would it make if the government announced that all market pounds would be 500 g and if you ask for a pound, you will get 500 g. The price for 500 g would be based on either one half of the kilogram price or 5 times the 100 g price.

    This could also carry over to other units as well. An ounce, both liquid, dry and troy would be set to exactly 30 g. Thus 10 ounces would be measured out as either 300 g or 300 mL depending on whether it was dry or liquid.

    Inches would be in increments of 25 mm and a foot 300 mm. This way you dispense with the expense of sell inch based or dual tape measures for measuring. The yard could be abandoned for the metre. Quarts would be abandoned for the litre and pints for 500 mL, except for beer and ales where it would continue to be 570 mL based on the 570 mL standard glass size.

    The mile could become just 1500 m or maybe 1600 m for sports. It wouldn’t matter as these units would be illegal for trade and use, just for estimation. If the Luddites can easily estimate old dimensions there wouldn’t be a need to revert the market scales to pounds.


  2. @Daniel The best way to get people to get use to metric is by getting them used to metric as it is and relating to things in metric, not redefining old units in slang terms. A good thing about the metric system is that all the units relate to each other which makes it easier to understand things in context of others. E.g if you know a box weighs 40 kg and you weigh 80kg you know the box weighs half of what you do which makes it easy to make an assessment relevant to that. While with rounded pounds people would still be thinking in pounds and would still be converting to and from that.

    I am also going to say in the UK at least people who can be considered luddites are quite a small minority. Most people are ambivalent and use imperial out of habit rather than because there is a strong attachment to it. The whole metric martyrs thing was 20 years ago and gathered media attention due to the absurd lengths one individual was willing to take to avoid getting a new scale.

    Metric only food packaging was introduced a few decades ago without much issue and this recent push was a desperate attempt to appeal to party members as well as a way to distract from other things. With it proving that there is little appetite to revert back. I wouldn’t be surprised if Truss just moves on to other things and it is not brought up again.

    Liked by 1 person

  3. Daniel, UK is supposed to be a high tech modern country. The idea of some set of ‘customary measures’ belongs to the 18th century, before electricity proved it was useless for modern living.
    Let there be but one set of units, throughout the planet Earth, and even more so on the Moon, Mars and beyond.
    If the human race cannot manage that vital yet so simple a task I wonder how we get anything done other than by accidents.

    Liked by 1 person

  4. Alex said: “The best way to get people to get use to metric is by getting them used to metric as it is and relating to things in metric, not redefining old units in slang terms.”

    This is only true in the case of those that WANT to learn and use the metric system. No matter how much you try to teach these Luddites about how SI is better and easier, you’re wasting your breath. They don’t want to hear about it.

    Recycling old unit names to modern metric values has worked in other countries and reduced the resistance towards metrication. In the anglosphere countries that didn’t do this , with some exceptions, the population still resists.

    Yes, we the choir all want to see a completion of the metrication process, but it isn’t going to happen if the old units are still in use with their odd conversion factors to SI. Instead of promising a return to imperial, redefining the old units to rounded metric values would have prevented this problem from ever erupting.


  5. The key to becoming familiar with metric is to see and use it every day. Road signs in metric are the ideal tool to accomplish that. Virtually all the world has them. Why can’t we?


  6. metricnow,

    To answer your question, that is because the people who have run the DfT over the past 50 years have a personal hatred of the metric system and have gone out of their way to make sure the road signs stay imperial. Be thankful though the metric system is used behind the scenes in the engineering , construction and maintenance of roads and bridges.


  7. @Daniel with the possible exception of the pint when it comes to pubs I really don’t see how doing that would improve the situation. Nearly every food item is sold in metric quantities and people are use to it by now. The two bigger sticking points is the road signs and personal measurements. Road signs are wholly the responsibility of the government and it wouldn’t be helpful at resolving personal measurements.

    An easy way to help the situation when it comes to such personal measurements would be to stop supporting the usage of conversions and give it in metric only. The NHS BMI calculator still defaults to imperial despite working wholly in metric internally.

    “To answer your question, that is because the people who have run the DfT over the past 50 years have a personal hatred of the metric system”

    The DFT is a governmental department. As such it is held accountable and is set up to reflect the policy of whatever government is in power at the time. If the government was committed to seeing the completion of metrication on road signs, the DFT would be made to reflect that. The failure to do so is because of the lack of interest from successive governments.


  8. The Government’s proposals, if implemented, won’t be the first reversal of metrication in the UK. In 2001, road signs at each end of new traffic calming measures installed outside my local school read, “Humps for 300 Mtrs”. About 2 years later they were replaced with signs saying, “Humps for 300 yards”.

    Re-introducing pounds and ounces in the UK, 23 years after they ceased to be legal for trade, would be a much more significant reversal of metrication than the set backs in Canada in the 1980s.

    The move would necessarily lead to an increase in complexity of weights and measures legislation, and an increase in the number of regulated weights – the very opposite of deregulation. It would obviously also cause a lot of confusion. These days basic imperial conversion factors are deemed worthy of questions on Mastermind.

    Using different pounds and ounces from the ones a lot of people still use when talking about baby weights would be doubly confusing.

    For traders still using optional supplementary unit prices marked in avoirdupois pounds, alongside official metric unit prices, there is zero chance of them switching to more expensive looking mesures usuelles prices.

    Napolean’s measures, and UKMA’s views on adopting them, were discussed in a previous Metric Views article:


  9. Alex M wrote “The NHS BMI calculator still defaults to imperial despite working wholly in metric internally.”

    This really is quite scandalous given that the vast majority of the British public are metric-educated. There’s not better place to start using it than with your own body weight and height. That’s where you actually have to think a bit as opposed to simply buying something marked in metric or filling up the car in litres, where you eye is probably more on the price than the quantity anyway.

    Should UKMA be lobbying the Department of Health to change their BMI calculator and to encourage people to start using the same units as the medical staff? I’m sure many more people know their weights and heights in metric than is often assumed.


  10. Alex M wrote “The NHS BMI calculator still defaults to imperial despite working wholly in metric internally.”

    What I think is also scandalous about this app is that when you do use metric, height separates out m and cm, weight separates out kg and g, in the same manner as you would feet and inches. It really is frustrating to use.

    Thankfully for those of us with iPhones, BMI is now calculated when you go to update it (the fact it doesn’t update automatically when you change your weight is more an annoyance).


  11. @Free Thinker
    What a crazy way for an app to present metric as if it were Imperial instead of using metric appropriately with the right unit prefix along with a single number (including maybe a decimal fraction after the decimal point). Calls into question how metric really should be used.


  12. We have departed somewhat from the subject of this thread with our comments on how metric units are displayed on the NHS’s BMI calculator. I am all for displays being correct, but the focus should really be on getting people to use the metric rather than being overly concerned about the precise way the information is displayed. If it is any consolation, I know from other European countries that they do not always display metric figures or symbols correctly either. I have seen the ‘xx m xx cm’ format before in another perfectly and fully metric country, so no ‘imperial contamination’ there I would have thought. I wonder if this helps or hinders the discussion.


  13. Metricnow,

    I disagree with your assessment. How metric (actually SI) is used is as much important or even more so important then getting people to use it. SI needs to be taught and used correctly or else you end up with misunderstanding and confusion. SI is the standard system and is quite different in format than either FFU (Fake Freedom Units) and old cgs metric which is still in common use in long time metric countries.

    Everyone who supports metric claims it is based on tens or is a decimal system. The only thing 10 about metric is the relations of the six prefixes around unity. In SI, however, those prefixes aren’t used and the rest of the prefixes are based on increments of 1000. Also, all of the SI units are related to each other on a 1:1 basis. Many units in old cgs don’t have this simple relationship with each other, such as calorie, atmosphere, torr, gauss, etc.

    In old cgs metric, like FFU, the prefixes are restricted and the addition of counting words are used to measure outside the range of prefixes. Old cgs metric and FFU have equivalent units that make neither set of units advantageous over the other. You have centimetre and inch, gram and ounce, kilogram and pound, kilometre and mile, litre & quart, etc.

    In SI, you use all of the prefixes to scale any measurement into the range of 1 to 1000. In old cgs metric the moon is 384 000 km, in SI it is 384 Mm. The sun is 149.5 Gm in SI, in old cgs it is 149 500 000 km. The practice of most people who use metric is to use it just like FFU. So, what is the advantage of changing?

    We need to discuss the importance of using SI correctly to its advantage and not just push others to use old cgs metric in the same way they use FFU, otherwise there is no reason to change.


  14. Daniel:

    Thank you for your reply and I take your point entirely. I also think we have disagreed on this issue before. The priority is to get people using and thinking metric. The tidying up exercises and all the symbols less used in ordinary life can come later. You have to learn to walk before you can run.


  15. Metricnow,

    The priority is to get people using and thinking in correct SI from the beginning. If they “learn” bad SI or use SI in an inefficient way, they will never want to relearn the correct way at a future date. There won’t be a tidying up later. Just a lot of complaints about having to learn metric then having to learn it differently because they learned it wrong to begin with. Then the outcry would be they should have stuck with FFU.


  16. Agree with Daniel. As the old saying goes:
    “As the twig is bent, so grows the tree.”


  17. @metricnow I’m with Daniel on this too… some use the excuse that they find metric measures difficult to understand and having official sites and apps with nonstandard usage does nothing more than perpetuate the myth that there is something complicated about SI.



    An interesting article. Here is an excerpt:

    In certain ways, the UK was dragged kicking and screaming towards metrication; the use of ‘supplementary indications’ (use of equivalent imperial units) continued far longer than intended due to public resistance to their removal. Logical arguments for metrication can fall flat in the face of a nationwide emotional attachment to imperial units, which seem to evoke an inexplicable sense of organicity and a more explicable sense of Britishness (especially when compared with the seemingly technocratic and French metric units). Imperial units are more than a nostalgic element of national identity. They are associated with a time when the British Empire quite literally ‘ruled’ its colonies in imperial units: an age that a vocal part of the population looks back on fondly.

    The problem is, no one today was alive when the empire was at its peak. Very few have any idea of life was really like for the masses. In the time of the empire, the vast majority were impoverished and lived in want and squalor. It was a time of prisons for those who fell into debt. Only a few had wealth and privilege. You can’t bring back imperial without bringing back poverty.

    Maybe today’s collapse of the English economy and increased economic instability and poverty is just another aspect of the return to empire. There’s an old saying. “Be careful what you wish for, you just might get it” and boy are they getting it.


  19. If things keep going the way they have been for the new government, there could be another general election before a switch back to Imperial gets implemented seriously. In that event a Labour government is quite likely, resulting in the scrapping of Imperial back into the rubbish bin. One can only hope that’s what is coming!


  20. It was the French law of 1840 July 4 that mandated the return of France to the metric system from 1840 January 1. The Netherlands took the gamble of going metric in 1820, thus in fact becoming the first metric country in the world – an oasis in the desert of rejection. It was from 1840 onwards that the metric system began to spread all over the world. And sometimes I still read that we owe the metric system to Napoleon!
    In 1810 The Netherlands became was annexed by France and thus the attempt was made to bring in Napoleon’s customary system; however, in 1813 the French were expelled and that was the end of Napoleon’s system in our country.
    It is also my conviction that US Customary is the successor of Napoleon’s customary system (Mendenhall Order 1893). And even Imperial went this way in 1959. Customary systems are therefore second hand metric systems and are as such totally redundant. When I found out that the US standards of length and mass are the metre and the kilogram I was shocked.


  21. @Han. When the metric system was introduced in France in 1799, many people were illiterate and did not understand the “new system”. To make things simpler, “new” units were introduced in 1801 – the “palm” (or hand) could be used instead of 10 cm, the “el” instead of the metre, the “thumb” (or finger) instead of 1 cm and the “line” instead of 1 mm. These units could be used instead of the official units. (Obviously, the French equivalents of these tersm were used).

    After the Kingdom of the Netherlands was established and the metric system re-introduced by Willem I, the French terms for “palm”, “el”, “thumb” etc were translated into Dutch and could be used as an alternative to the “official” metric units. These can be seen in a classical Dutch arithmetic book dated 1824 at

    Off-topic: When Napoleon absorbed the Netherlands into France, he required that everybody in the Netherlands should have “proper” surnames. (In the northern provinces of Friesland and Groningen, the use of patronyms was still common). As a result, in December 1811, one of my ancestors adopted the surname VLIETSTRA.


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