Joules – rare but minor progress for metrication

After many recent setbacks, it is pleasing to report a small but significant bit of progress in the long campaign to make the metric system (SI) the default system of measurement in the UK.  This minor (but perhaps somewhat pyrrhic) victory concerns front-of-pack (FOP) labelling.

Examples are beginning to appear in the shops of FOP labelling such as the one illustrated below.  This is in accordance with EU Regulation 1169/2011 approved in 2011 and shows energy content in both kilojoules (kJ) and kilocalories (kcal).


Both package labelling and measurement units are matters of EU competence, and the European Commission consulted member states on new Regulations which would apply throughout the EU.

Unfortunately – and to their discredit – the UK government argued for FOP labelling to show “calories” only, with no joules. This was their comment in a response to their own consultation in 2012.


We recognise that the provision of energy information in two units of measurement may both restrict space available on pack and impact on consumer understanding of this information. The UK lobbied hard on this issue. However, the Units of Measurement Directive 80/181/EC (as amended) commits all European Member States to use internationally agreed units of measurement – for energy this is kilojoules. We could not secure derogation from the existing Directive during negotiations. The EU FIC therefore states that energy must be labelled in kilojoules as well as kilocalories.”

Note that, instead of explaining or defending the long-term benefits of changing to a scientifically based system, the UK document tries to blame the EU for overruling its attempt to undermine the Units of Measurement Directive.

Sadly, the UK Government were joined in their short-sighted and unscientific lobbying by the Consumers’ Association (Which), who wrote:

“When the energy content is provided, it is important that it is given as calories (Kcal) [sic] on front of pack and that this information is not confused by additional kilojoule (KJ) [sic] information. It is important that the interpretation of the EU Food Information Regulations allows for provision of Kcal [sic] and KJ [sic] information on back of pack, but that it does not over-complicate front of pack nutrition information. Providing energy in both units would negate the point of simplified front of pack nutrition labelling.”

[It is indicative of Which’s level of understanding that they cannot get the symbols right!]

The UK Metric Association (UKMA) had argued that the proper scientific measure, the joule, should be used exclusively and that the obsolete “calorie” should be discarded.  Regular readers of MetricViews will know that the joule is part of the International System of Units (SI) and that it is directly related to other units, whereas the “calorie” is an anomaly as its value is determined by experiment (basically heating distilled water) rather than by definition. See this article.

The problem of course is that the “calorie” is deeply embedded in the public mind, in the media, in the food, health and weight-watching industries and in many otherwise wholly metric countries.  Defenders of the “calorie” claim that since the general public is familiar with this unit, it would be confusing to try to replace it with a different measure.  They also argue that giving both units would be even more confusing.

UKMA would agree that giving both units is undesirable – but for a very different reason.  Experience in other fields (e.g. price marking and quantity indication in retailing) has shown that displaying dual units simply enables people to relate to the unit with which they are familiar – and ignore the unfamiliar unit.  No progress is made in achieving the changeover to proper metric units.  It is another example of the failed policy of “voluntary gradualism” that has bedevilled the UK’s metrication efforts for nearly half a century.

It is for this reason that UKMA favours a “clean break” with the obsolete units.  If people can learn to cope with the internet, smartphones and DVD recorders, then joules should be a doddle.  All you need to know is that the average energy needed by an adult is 10 000 kJ (10 MJ) per day (slightly more for a man, slightly less for a woman) – and relate your energy intake in kilojoules to that figure (obviously adjusted for your own personal lifestyle).

However, while we should be pleased that the European Commission has insisted on saving the joule, our pleasure should be tempered by the fact that the “calorie” has also been preserved indefinitely.  In practice this may make it even more difficult to delete it in the future.

Author: UK Metric Association

Campaigning for a single, rational system of measurement

35 thoughts on “Joules – rare but minor progress for metrication”

  1. UK Government: “… information in two units of measurement may both restrict space available on pack and impact on consumer understanding of this information”

    It’s refreshing to see official acknowledgement of what is already obvious to supporters of metrication – that the use of dual units hinders understanding and increases confusion. Previously, we have become accustomed to hearing specious arguments, from people and organisations who should know better, supporting dual units because they “add information” and “increase choice”.

    Judging from Cadburys’ website, it’s interesting to see that Australia seem to be ahead of Europe and the UK on the issue of kJ versus kcal. Their nutrition labelling includes no referrence to kcal. Energy content is exclusively in kilojoules.


  2. Outside scientific circles, calories were seldom used in the UK for measuring heat energy. Boilers were rated in British thermal units (Btu)/hour and gas was sold by the therm, equal to 100 000 Btu. On the continent, in contrast, the calorie ruled and the Btu was unknown. It makes British enthusiasm for the Calorie for measuring food energy and in the slimming business even more surprising – as an outdated metric unit, you would think we would be happy to kill it off. Another example of US influence, perhaps.


  3. This rather sad tale appears to mirror the political climate in the UK. Currently, it seems, the voice of the unenlightened, the jingoistic or just plain bigoted is ringing loud and clear whilst that of the moderate, rational and informed is suppressed. Evidence for this latter opinion may be found in the heavily politicised comments of the Food Standards Agency, etc. that seek more to appeal to a eurosceptic audience than to offer a considered, politically neutral, rationale regarding the merits of consigning the Calorie to history or not.


  4. Thanks Asda, when are the other supermarkets going to do it?

    Aldi, Booths, Budgens, Co-op, Costcutter, Eurospar, Eurospar, Farmfoods, Filco Foods, Heron Foods, Iceland, Lidl, Londis, Mace, Marks & Spencer, Morrisons, Nisa-Today’s, Ocado, Sainsbury’s, SPAR, Tesco, Waitrose, and Whole Foods Market

    With apologies for any left off this list – taken from Wikipedia:


  5. I received this comment from a well known journalist/broadcaster:

    “My understanding is that in France they use calories.. so this seems likely to confuse with no real benefit. “


  6. Great article, thanks. It prompted me to see more about Australia. Here is a website and mobile phone application that educates people about joules:


    8700 reasons to change the way you think about fast food
    New South Wales (NSW) Government media release – 1 March 2012

    Minister for Primary Industries, Katrina Hodgkinson today launched a new education campaign to encourage consumers to make informed choices about fast and ready-to-go food.

    Ms Hodgkinson said the 8700kJ campaign is focused on educating the public about their kilojoule intake and giving them easy access to information in order to make balanced food choices.

    The 8700kJ campaign follows NSW legislation which has seen the introduction of kilojoule labelling on menu boards since 1 February 2012.

    “Fast food chains with twenty or more outlets in NSW are now required to display the kilojoule content of all items on their menus.

    “It is a first for Australian consumers and NSW is leading the way when it comes to ensuring the public have the right information at their fingertips to make more educated decisions about their kilojoule intake.

    “The average Australian consumes 8700 kilojoules of food and drink each day, yet only five per cent of people are aware of how many kilojoules they should be consuming.

    “From today, to complement the legislation and new labelling system, consumers can visit to calculate their ideal kilojoule intake, search food outlets to see how many kilojoules are in the food they are eating, and learn about how exercise can help burn kilojoules.

    “To further help consumers make good decisions about what they eat, the NSW Government has launched an 8700kJ app which will be available on iPhone, iPad and and Android.

    Download it from:
    iTunes store
    Android Marketplace.


  7. The retention of the calorie, and its confusing symbols, cal, Cal, kcal, kCal, is not confined to the UK. It also occurs in another country, that has also partially metricated. That is the US.

    The following link connects to US blogger, “The Metric Maven”, and an interesting article of nutritional labelling from a US point of view. It compares nutritional labelling in the US, to labelling in Australia, which has metricated (but not totally metric) and have only SI units on their nutritional labels.
    Note: kilojoules are mandatory on nutritional labels in both Australia and New Zealand, but kilocalories may also be displayed as a supplement but are not mandatory.

    The link:


  8. I am elated that the EU has finally tired of giving the UK derogations and the practice is ended. What are the names of the people who sit in on these negotiations and demand such nonsense? I would be even more happy if the EU would review all of the past derogations and reverse them.

    Obviously Australia and New Zealand and possibly others have the smarts to know how to teach what is not understood. By introducing the 8700 kJ campaign they not only introduce the joule into the national mindset, they give a reference number that everyone can relate too. So, why can’t the UK, the US and any other nation clinging to calories do the same?

    I have to agree though that the EU regulation to require both serves no purpose unless it is just an intermediary step. Even though transition steps taken where both are used simultaneously never promote learning of the new, there is a comfort for some people to see the old. It then becomes their problem if the don’t take the opportunity to learn the new way when the old is finally dropped. At least though for those that prefer proper SI, the numbers are there and in rounded form.

    What can the UKMA do to promote the 8700 kJ program into the UK?


  9. When will you people learn? We want to keep pounds and ounces. We are British, not some kind of third rate quasi-communist European (god forbid, a Frenchman) who counts in tens, and that is precisely why two thirds are opposed to the slow degradation of our values through metres and litres. Why can’t you leave well alone?


  10. Wrong target, Mr Neece.
    The calorie is a metric unit – the energy needed to raise the temperature of one gram of water by one degree Celsius. Over the years, its disadvantages have become apparent, and it has been superseded for scientific purposes.
    No one is suggesting, as far as I know, that food energy should be measured in British thermal units.
    Incidentally, it was an American scientist who, in the 1880s, suggested that the calorie should be used to measure food energy.


  11. @James Neece
    Don’t we all count in tens then? I find that anti EU rhetoric a bit pathetic. Please do not include ‘me’ in your ‘we’.
    James Prescott Joule, a Salford brewer, was very much an English man, and the unit of his the joule was derived in his attempt to make English beer cheaper. It was I believe based on the foot – pound before calculating the electrical units which have never had Imperial definitions.
    The Calorie on the other hand was the work of one Nicolas Clément, a Frenchman, and is based on the gram and degree C.
    Now which one was it you wanted ‘us’ to use? The usual French aka EU stupidity falls flat on its face on this issue. Never mind, don’t let any facts nor common sense get in the way of a bit of EU bashing.
    Before anyone reminds me, I am fully aware that metrication in the UK has nothing to do with EU nor Europe. It pre-dates EU by some years. ‘WE’ invented it!


  12. First of all James, your “we” does not include me or others who support the final completion of metrication. What I want to know, is where have you been hiding for the past 30 years? Except for some minor hold-outs, the British economy is fully metric.

    You obviously don’t shop in supermarkets or you would have discovered a long time ago metric only packaging. You obviously don’t visit the deli counter, or you would have noticed the scales are in grams, not pounds and ounces. You obviously don’t buy petrol or you would have noticed the pricing is in litres. And you don’t obviously listen to weather reports for they are given only in metric.

    So how is it you have been able to avoid a culture of metric for decades?

    Communist European? Where did you dig that one up? The last time I checked, communism died in Europe in 1989, some 20 plus years ago. Are you sure your name isn’t Rip van Winkle?

    You may be surprised to know that since the metric system was developed in France in the 1790s, it has spread across the world, not just France or Europe. Every country once under English rule as part of the British Empire is now metric. They aren’t complaining, so why are you?

    You can keep your old ways if that is what makes you happy, but you will not keep me from moving forward and enjoying the benefits of the metric system and the economic wealth it brings me and those like me.


  13. @James Neece:

    James – you are way, way off-base here. Firstly, all is NOT well with the current hodge-podge set of imperial measurement units some in Britain (but less than the two-thirds you assert) persist in using. Imperial is simply not fit for purpose in the 21st century (and wasn’t in the 20th), which is why the British government of the day in 1965 committed the UK to make SI the only official measurement system for this country – and this was BEFORE we thought about joining the common market, as the EU was then known.

    Secondly, you make the all too common common error of equating conversion to the metric system with Europe (which of course includes countries besides those in the EU). Going metric has NOTHING to do with Europe, but everything to do with getting this country using a modern system of measurements that almost the entire WORLD uses. Why you think that using the metric system makes 95% of the world’s population like “some kind of third rate quasi-communist European” boggles the mind – I’m sure that any Australian who’s proud of his country (one of the most metric English-speaking countries in the world) would not take kindly to hearing you use that expression about him or her. My advice would be for you to stay well away from Australia!

    Finally, you appear to imply (though you don’t actually state) that the current Imperial collection of measurement units is somehow British. Nothing could be further from the truth. Whether using miles (Italian), pounds and ounces (ditto), degrees Fahrenheit (German), and possibly other imperial units, their roots are very European. The roots of the metre are however very British (just that the French adopted the metre centuries before we did), while the modern Celsius temperature scale is a subset of the kelvin scale, created by Lord Kelvin – just how British can you get?

    I suggest Mr Neece you do a little research before calling metric supporters “some kind of third rate quasi-communist European” – nothing could be further from the truth.


  14. I have a question..

    With reference to EU Regulation 1169/2011, I have looked through the document that you have linked to, and its my understanding that the displaying of energy content in calories (kcal), is not mandatory. Can I ask that one of your legal people confirm that please?

    Also, if the EU Regulation 1169/2011 states that the displaying of kcal is not mandatory, is there any UK regulation, or law that states that kcal must be mandatory?

    In other words is it the law within the UK that packaging/labelling companies must display energy content in kcal or it optional?

    Thanks in advance.


  15. @WJG

    American here, so don’t take this as authoritative. Annex 15 appears to require both:
    “The units of measurement to be used in the nutrition declaration for energy (kilojoules (kJ) and kilocalories (kcal)) and mass (grams (g), milligrams (mg) or micrograms (?g)) and the order of presentation of the information, as appropriate, shall be the following:” (table follows)

    In addition, the calculation method in Annex 14 appears to support both. By contrast, American nutrition label rules require kilocalories (marked as “Calories” with capital C), and allow supplemental information in kilojoules.


  16. @WJG here is a copy of my post on the Which? comments page. The link no longer works, but a search on “” finds the document.
    Re-post: –
    In answer to my own question the link is

    Article 6 on page 6
    1. The declaration of the energy value and of the proportion of
    nutrients or their components shall be numerical. The units to be used
    are the following:
    — energy — kJ and kcal
    — protein
    — carbohydrate
    — fat
    — fibre
    — sodium
    — cholesterol milligrams (mg)
    — vitamins and minerals the units specified in the Annex

    2. Information shall be expressed per 100 g or per 100 ml. In
    addition, this information may be given per serving as quantified on
    the label or per portion, provided that the number of portions contained
    in the package is stated.

    This comes into effect on 12th December 2014
    Report this comment
    Posted 3 February 2013 at 3:46 pm
    1 – 0″
    Hope this helps.


  17. Perhaps Mr Neece would care to have a read of this web page:

    It spells out clearly the extent of British involvement in the development of the SI and the fact that historically pounds and ounces originated elsewhere.

    I am British and proud of it but that does not mean I have to stick with awkward, illogical and outdated measurement units. Our traditional strengths lie in many other things such as common humanity and a free democratic society. It also embraces the freedom to express our view that Britain should complete metrication for sound practical reasons.


  18. Having re-read James Neece’s comments, and looked over all our replies to his post (including mine), I wonder if he wasn’t just winding us all up. He must have known the nature of the replies such a comment would elicit, so why post it in the first place? If his comment was to wind us all up, I suppose you might say he succeeded in a way, but what a pathetic thing to do.


  19. @WJG

    Annex XV begins as follows:

    The units of measurement to be used in the nutrition declaration for energy (kilojoules (kJ) and kilocalories (kcal)) and mass (grams (g), milligrams (mg) or micrograms (?g)) and the order of presentation of the information, as appropriate,
    shall be the following.” It then lists kJ/kcal (in that order of precedence).

    So there is no doubt that both are required. In any case the UK could not (legally) override a mandatory EU requirement.


  20. Metric Views has heard from Mr Neece before, on the thread re London 2012, for example, where he also implied that the UK move towards the adoption of modern metric units of measurement is a European or EU plot, a claim refuted by Erithacus.

    Not only was the proposal for a decimal (metric) system of measurement first proposed by a Briton (Bishop Wilkins) in the 17th century, but more metric units are named after British scientists than scientists of any other country in recognition of their contribution to the metric system and, as pointed out above, the remaining Imperial units in use today are anything but British in origin.

    The metric system is British through and through.


  21. The British Heart Foundation – perhaps there might be progress before Christmas

    Heart Matters, a magazine produced by the British Heart Foundation regularly has recipes which only show Calories. The latest edition also contains an article with this inKorrect symbol: Kcal shown many times.

    I wrote to the editor pointing out not only the wrong symbol but also explained the need to give energy values in kilojoules (kJ). I provided the example of the Asda packet.

    The reply is below:
    “Thank you for your email to the British Heart Foundation.
    At present, the term kilojoules is not commonly used by the majority of our readers, nor are these the units that are used on the front of pack labels they use to inform their food purchases. Which is why we referred to calories in our article on portion sizes.

    However, we are aware of the European regulation and change to use kilojoules for nutritional information on packaging and as this begins to be implemented more widely by manufacturers and retailers we will also play our part in helping consumers to understand what this means. In addition to this, once the thresholds and format for front of pack nutritional information have been confirmed by the department of health, we will be using these to present the nutritional information that accompanies our recipes. This will include information on their energy content presented in kilojoules.”

    This raises a query, when will the Department of Health confirm the format for front of pack information? I thought that a voluntary agreement has already been sorted out.


  22. Jake,

    The concept of a base 10 decimal system did not start with John Wilkins. It goes back further to pre-Norman Britain. It was the Norman French, and other European invaders that brought the ancestor of imperial to the UK. Such hypocrisy to bad mouth Europeans for bringing metric to the UK and then support a more ancient system that was forced on the UK by the ancestors of modern Europeans.

    I’m sure everyone is familiar with the term wand. It is in reality a pre-Norman unit of length equal to about a modern metre and formed part of a decimal measuring system similar to the one John Wilkins came up with.

    In the Anglo Saxon language the word Wand was a pre- Norman unit of length used in the British Isles equal to approximately the modern metre, apparently dating from an early use as a yardstick. The old English unit of 1007 millimetres was called a ‘wand’, and although the ‘yard’ was created to replace the wand the wand was still used for some centuries because of its convenience as part of an old English decimal system that included:

    10 digits (base of long finger) about 20 millimetres
    10 digits = 1 small span (span of thumb and forefinger) 200 millimetres
    10 small spans = 1 armstretch (1 fathom from finger tip to finger tip) about 2 metres 10 fathoms = 1 chain about 20 metres
    10 chains = 1 furlong about 200 metres
    10 furlongs = 1 thus-hund of about 2000 metres

    The wand that has survived today as part of folklore may in fact be a rendition of the ancient British length unit. Thus a true wand would be a metre in length and not 30 cm.

    Once the yard was fully established, the Wand came to be known as the ‘yard and the hand’, and then it disappeared, either slowly or by being banned by law by the Normans.

    I believe that John Wilkins was aware of the ancient decimal system used in pre-Norman Britain and made an attempt to restore it. But it took the descendants of the Normans who brought Babylonian units to Britain to bring an updated version of historic British units to the world. In more ways than one, metric is truly British in origin.


  23. John,

    I don’t think James Neece came here to wind us up. I think he came here out of anger and frustration. It is obvious from his post that his personal resistance to metrication is failing and he is lashing out at the very people he blames for making his life miserable.

    If you look at the questions I posed about encountering metric everywhere in one’s life, it has to frustrating to have to pretend the metric doesn’t really exist or to have constantly convert every metric dimension to imperial. I can’t imagine having to do that all day.

    One would think it would make more sense just to adopt and go with the flow. But, some people would rather get angry and blame others.


  24. @Philip
    I find it very strange, not to say bizarre that so many large organisations (including government) take this chicken and egg attitude. “No one else is using it so we won’t; we are not using so others won’t either”.
    Now, if no large, public sponsored organisation will start the ball rolling then how do the general populace start using it? As the general populace don’t see it, they cannot start using it, therefore the big organisations won’t start using it … so it goes on add infinitem.
    Dual labelling will do little as the vast majority will continue to use what is ‘familiar’ to them so the new will never come to the fore.
    I can’t myself start using it because my friends don’t (and won’t), they can’t use it because I don’t know I want to.


  25. John Frewen-Lord is maybe correct, Mr Neece is just a wind up merchant, he is certainly no historian thats for sure.


  26. Having said all that about the ‘wand’ (very interesting, I didn’t know about that before), it must be noted that if the wand was part of the Anglo Saxon weights and measures system, then surely it too is an import! An import from about the 6th century maybe, but an import all the same.

    The Romans had left, and in came the Saxons, Jutes and Angles bringing their measuring systems with them. Strange then that pre-metric Germany wasn’t still using a derivative system based on decimals if the Saxons, Angles and Jutes already had such a system that far back.

    Unless of course, you’re suggesting that the Anglo Saxon invaders developed their decimal wand-based system after they got to Britain? In which case the people left back in “the old country” would never have heard of it.


  27. Two of the arguments of metric opponents against metrication is that imperial and all of its variations is it time honoured and that metric has been forced on the population against their will.

    I don’t know where the wand originated and by what nation, but the fact is a decimal measuring system close to modern metric goes back about 1000 years, showing that metric is just as time honoured and natural.

    It also shows that conquering powers forced a change over from this early metric system to the pre-imperial of Continental Europe. The very thing in reverse that the present opposition is complaining about. The conclusion being that metric is more British than imperial and imperial was forced on Britain by outsiders not the other way around.


  28. Still and all, the changes in the UK put you folks kilometers ahead of us in the States.

    There is a move afoot to shove the “calorie” aside:

    Unfortunately, it’s not about introducing “joules” but instead adding an exercise equivalent to help consumers supposedly get a better idea of the energy value of the food they’re ingesting. This smacks of the use of time to indicate distance as some signs (in London?) now do. This is clearly a step backwards for us in the USA.

    Maybe some day we’ll joint the rest of you folks and finally ditch the “calorie” for what its replacement ought to be: the “joule” and Americans can actually learn to think about energy correctly. 😉


  29. Ezra,

    That someday won’t happen in my life time if those running the US government have a say. They are totally opposed to metrication as was recently shown in a response to an online petition to complete metrication. Here is their response:

    So, in their own words, you are free right now to measure your energy usage in joules and the rest are free to continue to use the calorie. Of course your freedom does not extend beyond the walls of your own home, for you will receive no support for your choice to personally use metric in the streets and markets.


  30. No progress in education.
    School examination papers are still ‘promoting’ calories – unit: Kcal …
    Exam Board WJEC CBAC June 2017
    Food Science & Nutrition Exam Paper
    One question provided information which included:-
    “Weekday & Weekend Daily Intake” – the values given were only in ‘Kcal’
    We know The Royal Society recommended doing away with calories in 1972; see link:

    No more consultations are required. Just strong government legislation – with enforcement. And sadly, don’t expect cash-strapped local authorities to do any of the enforcement. Also note – if a local authority’s trading standards dept. fails to enforce regulations, it’ll probably be a waste of time making a formal complaint to the Local Government Ombudsman because the LGO doesn’t have the necessary powers to ensure Trading Standards do their job.


  31. It seems that those countries that went metric a hundred or so years ago and adopted pre-SI units that were in time deprecated never stopped using these units. It isn’t just the joule that suffers from slow acceptance, it is the newton, the pascal and the watt too. The only use for the watt is where it has been for the past 10 years, a measure of light bulb power.

    The gram and kilogram are still pushed as force units, the kilogram per square centimetre is still found on some tyre pressure gauges. In some countries the psi is used instead of the pascal.

    It isn’t just the English counties that need to complete metrication, it is the metric countries too. They need to get rid of deprecated non-SI units as much as the new metric countries need to get rid of remnant traditional units.


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