A paradox of our measurement muddle

Should the UK have one measurement system or two? We highlight a paradox in UK government policy.

In 1789, France was sliding towards bankruptcy. In the preceding two years there had been three ministers of finance, none of whom had been able to obtain agreement on a way forward. In desperation, the King agreed to call a meeting of the Estates General, an assembly of representatives of the nobility, of the clergy, and of those who were members of neither. But in April, as the representatives headed for Versailles, finance was not the only issue on their minds. In particular, many were asking for standardisation of weights and measures.

This is not surprising. It is estimated there were about 800 different names for measuring units in France at that time. Each town and county had its own units, so that, with these regional alternatives, there were around 250 000 variations.

In contrast, in England Magna Carta had established in 1215 the principle of a single measurement system. It said, translated from the Latin, “Let there be one measure of wine throughout our whole realm; and one measure of ale, and one measure of corn …; and one width of cloth … .” This principle had then been extended to Scotland in the Act of Union of 1707. Trade and industrial development benefited immeasurably. However there has always been a tendency for new measures to appear, not least because traders often prefer confusion despite customers preferring clarity. By 1820, it was clear an overhaul was due – there were, for example, eight different gallons – and the Weights and Measures Act 1824 resulted. This initially applied to Great Britain and Ireland, but was quickly adopted throughout the British Empire – in trade, it helps if both parties are using the same measurement system.

Meanwhile, after its adoption by the Low Countries in 1820, the metric system had made steady progress around the world. By 1900, it had been adopted by scientists everywhere, and by the middle of the twentieth century was in use in most countries for most purposes. Then, in 1956, India announced it would be adopting the metric system. Imperial measures had outlived their usefulness, and had become a handicap not an advantage in trade and manufacture. In April 1965, the UK Government announced that the UK was to go metric with a target of 10 years. The 750 year-old principle of a single measurement system was upheld: metric would replace Imperial.

Most Commonwealth countries followed the UK’s lead and then pushed on to complete their transitions to metric measures. In contrast, successive UK governments dithered – the job was “too difficult”. So now in the UK we have a two-system measurement muddle and a Prime Minister who boasts in his New Year Message that he intends to add to it.

So here is the paradox. The present UK Government, English Nationalist in all but name, says “Let there be two measures” and pursues a very un-English policy of permitting the use of a mix of two systems.

An example of a muddle of measurement systems created by successive governments is described in the Metric Views article “Inconsistent motorway emergency features”, posted in December 2021. Our potential trading partners around the world are probably looking on with bewilderment and disappointment, our competitors with glee, and the French with a shrug.

17 thoughts on “A paradox of our measurement muddle”

  1. It is nice to have two systems of measurement same as there are different languages. Nearly everything now appears in shops as metric units,and, to some extent, we have got used to this,ie oz not seen now. However there is confusion with the metric system when its not applied correctly,ie to use litres when it should be kilograms.
    There are some units that may never change that is temperature we all use Fahenheit and we still use pints for milk etc so just leave it as it is!

    Liked by 1 person

  2. “We all use Fahrenheit”, er…. who uses Fahrenheit? The newspapers and TV news have used used Celsius for at least 20 years, the government itself uses Celsius, the Met Office uses Celsius, all schools teach Celsius, all scientists use Celsius (unless they use Kelvin, 1 K is the same unit as 1 C). In the general population, no one under 40 will have any experience of using or hearing Fahrenheit in daily life, and for anyone over 40 it is becoming a fading memory. Fahrenheit is far harder to understand (water freezes at 32 degrees, WTH? versus a nice simple zero Celsius). But yes, Fahrenheit is a symbol of nostalgia for older people (largely the current UK government’s supporters), and a symbol of nationalism = not using dirty Foreignistani measurements (ignoring the fact that Fahrenheit was a Foreignistani!)

    Liked by 3 people

  3. The problem with having two sets of units is the confusion and cost increases it brings. The Commonwealth countries decided it was best to switch everything so that in the end, everyone was speaking the same measurement language. A person is never going to understand both equally, one will be understood and the other will always have to be converted to and from. This is confusing if you are shopping and everything is metric and you don’t know it because you refused to learn. If you are on the job and you don’t know the metric units the company is using, you are a danger to the other workers as you will need to constantly convert and any mistake you make can injure or cost someone their life. There is also the possibility that a person is passed up for hire and feels discriminated against for not being able to function in a metric environment because they prefer to use imperial.

    Mistakes made when two systems are used can become very costly. Is it worth the price if when funds are not abundant? Nothing is gained with two systems and the only justification comes from the Luddites who are unwilling to move forward and expect to be pampered. I can’t imagine how many English jobs will be lost or businesses close just from the threat of a return to imperial.

    Liked by 3 people

  4. Imperialsys seems to be living in a fantasy world if he thinks foreignheat units are still in use, they aren’t. The media doesn’t even report them anymore. Celsius is the standard now.

    Liked by 2 people

  5. The replies are the result of obsession with the metric system, and is the misguided beliefs. ImperialNo we have had celsius for over 50years, never waned from use.As this website suggests this is an unbalanced view for metric fanatics. We are doing very nicely with what we have, no need for any more metric propagander!


  6. Imperialyes: this is not about an obsession with the metric system. It is about having a clear and consistent system that everyone knows and can be expected to understand. It is the system of measurement taught in schools, for goodness sake, and that system is the modern, international system of measurement. The fact that the government has not completed the conversion and schools are ahead in that sense does not alter that fact that a complete conversion is in the national interest. What people wish to use in their private lives, converting back to Fahrenheit, pounds and ounces or shillings and pence is their business, but the shambles that exists at present does not reflect well on the nation.


  7. @ImperialYes: You stated that “… we all use Fahenheit and we still use pints for milk etc …”. This is simply not true. The against Fahrenheit has already been argued.

    On a small legal point, milk may only be sold by the pint if it is sold in returnable [ie glass] containers. Otherwise, the containers are in multiples of 568 millilitres and the imperial equivalent is an optional extra. Furthermore, most shoppers are unaware that the price of milk at the farm gate [ie the wholesale price] is always quoted in pence per litre. If you try Googling “wholesale price of milk uk”, you will get a large number of hits, but the Daily Express and Daily Mail are unlikely to be among them.

    Liked by 1 person

  8. Martin,

    You said: “Otherwise, the containers are in multiples of 568 millilitres”

    This is only true as far as the label is concerned. But the actual fill is going to be in increments of 5 mL as all modern filling machines are metric and can only fill in increments of either 5 mL or 5 g. 454 g is an impossible fill, the closest being 455 g. I don’t know what the actual amount is for English products, but for US products 454 g is always filled to 460 g, to assure they never come up undersized.

    This may seem to some to be a trivial point so why bring it up, but if labels reflected the actual fill and not just a converted imperial fill, you would see more rounded metric friendly values on the labels, even if not ideal. Those who see 568 and 454 on packages know the size is “true” imperial pretending to be metric, but if they see 570 and 460, they know it is metric and intended to be metric.


  9. Daniel,
    The International Organisation for Legal Metrology document “OIML R87 – Quantity of product in pre-packages” (https://www.oiml.org/en/publications/recommendations/en/files/pdf_r/r087-e16.pdf) is a recommended legal text to be followed for verifying the quantity of product in a packet when the product is pre-packaged. In summary, the recommendation assumes that in a batch of N items, n will be sampled and on the basis of that sample, the remainder of the batch will be accepted or rejected. In the case of 568 mL containers of milk, the average contents of the batch must be at least 568 mL, no more than 2.5% of the individual items in the batch sample may have a shortfall of 17 mL and none may have a shortfall of more than 34 mL.
    The recommendation also describes the process by which these estimates are to be made and also cites the allowable probabilities of the process giving the wrong answer – for example, a good batch being rejected because, by chance, the sample selected for analysis happened to be biased towards those that had short measure or a bad batch being accepted because, by chance, the samples selected for analysis were biased towards those elements that were over-filled.
    In countries that use this recommendation as a legal basis for customer protection, it makes little difference if the system is tuned towards 568 mL or 570 mL because management might well set the fill level to 575 mL to accommodate any adverse results due to statistical variations.


  10. Martin,

    I understand what you are saying, but I think you missed my point. I was referring to labeling with numbers that don’t match the actual fill. If the machines are designed to fill in increments of 5 g or 5 mL, then labels should reflect this. If the machine is set to fill a package to 460 g, then the label should state that and not 454 g. If a bottle is filled to 570 mL, then the label should reflect that and not state 568 mL.

    Where I see your point coming into play is, for example, a returnable milk bottle would be filled legally to an imperial pint. If the machinery could do 1 mL increments and 568 mL was possible, technically though 568 mL is less than an imperial pint. An imperial pint is 568.261 mL which means a fill of 568 mL is undersized, but under OIML rules 568 mL is a legal fill as it falls within the acceptable fill tolerances.


  11. Sure having two languages is useful, but people especially Imperial fans forget that Metric is universal but the US customary units are different on certain weights and measurements, and Myanmar and Liberia are in the process of completing Metrication, so no using two measurement systems isn’t a good idea…

    Liked by 1 person

  12. Lee Kelly,

    Having two or more measurement systems never was a good idea, that’s why it is such a big deal in Magna Carta. In the spirit of Magna Carta there needs to be only one system, not only across the land, but across the world and there would be since SI is the universal standard. But, since the Luddites want to keep their deprecated units, they are the ones preventing a single system for the whole world.


  13. I have read the back and forth on fill regulations with some interest, and noted that no one has quoted the exact regulations yet.

    These are set out in the The Weights and Measures (Packaged Goods) Regulations 2006 ( here), Section 8 marks out the specific labeling requirements and Schedule 2 lays down the procedures of the reference test for statistical checking of batches of packages in order to meet the requirements of regulation 4(1)(a) and (b).

    Section 4 of Schedule 2 lays out the mathematical formulas and the criteria of measurement.

    A more succinct summation can be found ( here) , see section 6 of the pdf.

    Liked by 1 person

  14. Why, oh why did the BBC News web site list “gallons” as primary (and “litres” as secondary) in their article on the artificial snow used in the Beijing Olympics and the amount of water used to make it? Does China use “gallons”? Nope. Does even the UK use “gallons”? Go to a petrol pump and have a look. And they didn’t even say if the “gallon” is the US kind of the Imperial kind.

    What the heck is wrong with the BBC? Not only should “gallons” not be primary, it shouldn’t even be mentioned at all. (Yes, most Americans would have to look up the conversion and, yes, I’m beating a dead horse, right? 😦

    See it here:


  15. Ezra, more interesting it is written by a Chinese BBC fact checking team member.
    Facts, No, checking, NO!!!
    Gallons (UK) or litres, Americans would still be none the wiser. Strangely it is 49m gallons, very precise given the context.
    It does make one wonder, but I have given up on complaining now.


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