A problem with symbols

A quest by one of our readers for a new washing machine has prompted a look at Britain’s confused approach to the use of symbols.

In Britain, there are many activities where the use of symbols is taken for granted.

For currency, we use the symbols £ and p without a second thought. We would not dream of writing £s5, P5 or 5 £s instead of £5. We are familiar too with the US dollar, $. And we take the euro, €, in our stride.

On traffic signs, we can recognise many symbols such as those for cycles, lorries, deer, roundabouts, humps or historic houses. Not to mention the steam locomotive warning of an un-gated level crossing and the letter P on a blue background for parking.

Even the non-scientific among us know some of the symbols from the periodic table of elements: H2O – that must be water; CO2 – watch out, carbon dioxide; and so on.

But when it comes to measurement units, we revert to the free-for-all that goes with abbreviations.

One of our readers, Philip Bladon, reports as follows:

“Does Hotpoint realise its mistake?

When visiting two different stores both specializing in white goods, on every new Hotpoint washing machine and condenser tumble dryer the inKorrect symbol ‘Kg’ was clearly visible.

Here is a list of the models seen:

1. Hotpoint Ultima S-Line   SWMD9437
2.  Hotpoint Ultima S-Line  SWMD 10637
3.  Hotpoint Aquarius 7Kg. WDD750
4. Hotpoint 9Kg HULT 943 Experience
5. Hotpoint 7Kg HULT 742
6. Hotpoint 7Kg HULT 763
7. Hotpoint 7Kg HV7L 1451
8.  Hotpoint Aquarius 7Kg TCHL 73
9.  Hotpoint Aquarius 8Kg TCFS 83
10.  Hotpoint Aquarius 8Kg TCM 580
11.  Hotpoint eco TECH 7Kg At WM 1/L 7151 STYLE
12.  Hotpoint Aquarius  AQC9 BF5E 9 kg; this had a ‘9Kg’ sticker on it.

On the 8Kg TCM 580 machine, ‘Kg’ appears about nine times.”

Other readers have probably encountered misused measurement unit symbols on numerous occasions: kgs, KG, KM, KW, kw, Kwh, and so on.

Which is unfortunate, as the SI use of symbols can be a powerful tool, conveying a precise meaning that should be understood everywhere.

So how did confusion in Britain arise, and what can be done?

Imperial is a measurement system without symbols. Perhaps Imperial usage has crept into the measures that replaced it. This may be an example of the maxim, old habits die hard.

(In passing, it should be noted that the Latin word libra, plural librae, provides the abbreviation, lb, for the Imperial pound weight and also the symbol for the money pound.)

So, is there anything that can be done?

Clearly, the continued use of Imperial measures on road traffic signs does not help: m for miles – that is an abbreviation, the legal symbol for mile is mile; yd and yds – one a symbol, the other clearly an abbreviation; ft and in are legal symbols but the DfT also uses ‘ and “ contrary to international conventions. Confused? So am I.

Education should lead to greater knowledge, although there is little evidence that current school leavers are better informed than their parents.

UKMA has published a Measurement units style guide, which sets out British and internationally agreed standards for the use of symbols in SI. It may be found here:


Copies of the Style guide were distributed to national and local newspapers, with little apparent effect.

Perhaps our acceptance of confusion around the use of symbols illustrates how difficult it is to persuade us to take measurement seriously.

Footnote: ‘inkorrect’   see: http://simetricmatters.com/inkorrect.htm

57 thoughts on “A problem with symbols”

  1. My biggest gripe is the use of ‘kph’ for kilometres per hour, instead of the correct km/h. All the British newspapers use it. Even the Sunday Times, to which I wrote protesting its use of this solecism. The ST commented at the end of my letter that the Oxford Dictionary specifies ‘kph’ as the abbreviation (sic) of kilometres per hour, and that therefore there was no reason to change.

    I browse many forums and blogs, some of which are measurement-oriented, or at least involve the use of measurements in some manner. I am encouraged that a large percentage of contributors do actually write ‘km/h’ (or at least some variant of this, such as ‘km/hr’, which while still incorrect, is at least is closer to the correct symbol). I guess it all comes down to education. Considering how many people mis-spell my name, the UK seems particularly sloppy in getting the written word right – including metric symbols.


  2. It’s only been the last year or so that weight limit signs on roads have started to use the correct letter “t” instead of “T” despite them referring to the metric tonne and I’m sure we’ve all see the not entirely legal road works signs pop up from time to time indicating “mtrs”. It’s easy to imagine how a population who see incorrect usage in “official” usage might go ahead and repeat incorrect usage too.

    It’s also disheartening to see some shop chains (and market stalls who actually comply with the law) using things such as grms, ltrs and kgs on displays and on packaging.

    To some extent I blame the growing trend of using text talk when writing things long hand. After all, if you can’t stop people from using things like “ur” instead of your/you’re (ignoring the fact that they probably wouldn’t get the apostrophe in the right place either) then you’re going to be on a loser if you expect them to use the right symbol for metric measures too.


  3. @John

    at least in the UK, it is possible to write either John or Jon (I know people who go by both – that’s confusing!)

    I must confess that whilst it does irritate me seeing things like kph, I’d much rather see that than mph. Having travelled abroad a fair amount of time and seeing localised versions of the symbols (such as km/t in Scandinavia for km/h, or cyrillic lettering used in Russia and Belarus) – perhaps I’m just desensitised to uses of abbreviations over symbols.

    I’m personally just happy to see metric used; I’m sure we’d all agree that seeing “5 ltrs” is ultimately preferable to seeing “10 pints” and “110 kph” to “70 mph”. I know many will disagree as this eliminates the usefulness of symbols, but I just prefer to see metric used over imperial.


  4. @ Charlie:

    I agree that seeing incorrect metric units is better than no metric at all, although ‘kph’ still jars. But it’s just not us Brits who can’t always get metric symbols right. This is from a Spanish website:

    ” La concesión de los 33 Kms entre Pontevedra y Carril…”



  5. In Ireland the correct symbols are used on road- and distance signs, including in the Irish speaking regions.
    I have seen a ludicrous objection to metric some time ago: the names of metric units contain too many syllables, so SI should be condemned. Yes, it is true, many Imperial units have only few syllables: inch and foot, (each one), mile (two), etc. However, I would rather pronounce a few more syllables than having to calculate an invoice with Lsd/ton.cwt.qr.lb. And when writing, everybody can use the symbols, so this syllable-argument is trumped-up nonsense.


  6. Well, for example, in Italy, which is one if the first fully metricated countries in history, sadly there is still a rather (subconscious) chaotic situation: for example, a restaurant or pizzeria could be advertised as distant “200 mt”, “200 mt.”, “m 200”, “m. 200”, and so on; also Km (the Metric Maven, however, would say that this is more correct, which we could even agree upon, from a rational point of view…) instead of km is quite easy to see, even on official road signs; and quintals (100 kg) are still widely used: a rather total (even if only formal) mess, thus, even in a fully metric country!

    Considering that Hotpoint (Ariston) is a subsidiary of Indesit… well, who knows, the Kg could perhaps be of Italian as well as of British origin?

    Anyway, the K (a magnifying prefix) could even be a good thing, if the SI were further rationalised in the future…


  7. Use of the “T”


    When the incorrect symbol T is used for bridge loading, I assume that in the unlikely event of a bridge being damaged by an HGV the vehicle insurers and driver can avoid liability. Does anyone know what the legal position is?


  8. To be fair, the source of the problem lies in the poorly thought out unit naming and symbol definition schemes used in the SI system. With the resulting, mostly case-sensitive, symbol system being unsuitable for everyday use.

    The prefix system leads to long, similarly starting names. For example we have: millimetre, millilitre, milligram. Human nature will tend to abbreviate them all to something like “mil”, which obviously isn’t optimal.

    Then we have the SI banning abbreviations and insisting on standard official symbols. This means everyone, including the illiterate, the stupid, the stubborn and the disruptive, have to be effectively trained in their use. mm, Mm, Mt and mT are all different things and must not be confused – on the other hand, ml and mL are the same thing! And more importantly, not only does everyone need to appreciate the subtleties of the symbols, but they also need to religiously comply with them at all times to avoid confusion.

    Additionally, the case-sensitive issue and the need for Greek letters means that not all the symbols can even be rendered correctly with standard industrial upper-case only labelling machines and stencils.

    It’s as if the SI doesn’t belong in the real world, but in some idealised mathematical utopia!


  9. A quick search of the online Oxford Dictionaries has yielded the following: “While kph is widely used as an abbreviation of kilometres per hour, the correct SI unit is km/h, and this is the generally preferred form.” So if the Sunday Times is basing its statement that kph is the abbreviation of kilometres per hour on that entry, it is deliberately choosing to ignore the rest of the advice, namely that km/h is the correct SI unit and is generally preferred. I had a minor success about ten years ago in convincing the Concise Oxford Dictionary (paper version) to drop its entry of kph for kilometres per hour and to include the proper SI unit km/h, which can be seen on the inner ring of speedos on UK-registered cars, so it is not particulary alien or strange to Britons. In their defence, it has to be said that dictionaries often reflect what the general public use and write rather than what is strictly speaking correct, certainly in their recommendations on grammar, but they do not normally extend that to including common misspellings as the ‘correct’ form just because so many people tend to misspell a word in a certain way. One wonders therefore why they quote incorrect usage for symbols for units of measurement.


  10. “kph” is certainly a valid abbreviation in English, but will mean nothing to an Italian who would write “chilometri all’ora”. The symbol “km/h” is of course meaningful to everybody regardless of language.


  11. @Rob, regarding “T” vs “t”

    I did some personal research on this a few years back (some of which may have even found its way onto this site at some point)…

    On the one hand the imperial ton is close enough to the tonne to not make a great deal of difference so I couldn’t see it ever being an issue, however on the other hand I did stumble on a document (I think it was Derbyshire Council but it was some years ago now) that made the point that signs labelled “TON” should be altered to avoid that council having any liability if anything bad ever did happen.

    Unfortunately the latter argument didn’t impress Peterborough City Council who are responsible for a sign outside Wansford Cambs which, 4 years after I reported it, still states “Weight limits 7.5 tonnes & 2 tons in Wansford village” (in all fairness they did actually replace the “TON” signs with newer “T” ones which were the prescribed ones at the time.

    You can see that sign in Google Street View here


  12. I raised the issue of the Daily Telegraph using “kph” over a year ago. Tom Chivers and Peter Hall were the worst offenders. I repeatedly pointed out this wrong usage to the Telegraph, finally getting banned for my trouble. Although on sober reflection it could have been expression like, “Call yourselves profession journalists? I’ve known smarter washerwomen.” And, “Where’s the metre, Muppet?”
    However, “‘km/hr’, which while still incorrect”: I dispute this as “h” is not the correct abbreviation of hour. Although obviously, metres per second would be far more appropriate as a measure of velocity.
    Next target; to stop the Daily Mail using “lbs” as an abbreviation of pounds weight.
    But hey, par for the course in UK trash culture. Hate it and leave it.
    Jack, the Japan Alps Brit


  13. HOTPOINT isn’t the only company which doesn’t seem concerned about using the wrong symbol for the kilogram.

    Early in May this year, during a telephone call to the NANTWICH CHEESE COMPANY a senior member of staff at this company assured me they were happy using the symbols Kg and KJ as they appear on their product labels and website.
    Examples include:
    Residence Reserve Vintage Cheddar 2.5Kg Block
    [‘If you’re looking for a cheddar with distinction that Residence Reserve is the cheese for you’.]
    Cheshire Cheese Energy KJ/Kcal 1536/371

    He added, their food consultants and trade organisations have not raised any concerns about the labelling.


    AND another …
    SMART cars produced in Slovenia, (and perhaps elsewhere), have the wrong symbol for the kilogram (Kg) on the vehicle identification plates. There is a bit of good news; in the owner’s handbook the correct symbol is used. But, unhappily when the Mercedes-Benz & Smart Technical Department was contacted about the wrong symbol (Kg) on the car’s ID plate, the response received was “ to contact the Smart Retailer requesting clarification, it is the Smart Retailer who can raise the issue with the factory for further investigation”.

    How many other vehicle identification plates have the inkorrect symbol (Kg)?


  14. Philip,

    There are those that believe that all prefixes for multiples of a unit should have a capital symbol. All of the prefixes from mega on upward do and so to be consistent the deka, hecto and kilo should too, thus D, H and K respectively.


  15. Tesco’s Delicatessen Counters
    I rarely visit a Tesco store, however yesterday I was in the largest one in Redditch (Worcestershire), and purchased something from their delicatessen counter.
    As expected the label that was printed off had the inkorrect symbol Kg.

    This is a problem I raised with the company many years ago; the reply from the Chief Executive’s Office said they do not intend to change it.

    I had the opportunity to mention this problem of the wrong symbol on printed labels to ‘Mike’ one of the store’s managers. He at least promised to contact the software engineers at Tesco to try and get the error corrected.

    So, IF a change occurs in the future – and the printed labels produced after weighing items on Delicatessen Counters always show ‘kg’ instead of ‘Kg’ – then some credit should go to Mike!



    Today I returned to the local store and saw a major problem with many of their shelf labels. Throughout the entire store – many different products – where there is a shelf label that has a symbol for the kilogram you’ll see the inkorrect Kg.

    It certainly looks like the company has adopted a slightly different shelf label, probably not only changing the font, but also introducing this error.
    I complained to one of the store managers while I was there.
    I added ‘who was responsible for this mistake?’ and ‘why wasn’t it spotted earlier?’

    [In a few places and on some products you’ll also see: ‘KG’]

    Later I phoned Tesco [0800 50 55 55] to complain about the inkorrect use of ‘Kg’ on the shelf labels. Initially I asked the person I spoke to ‘a simple test question’; would she kindly tell me the correct symbol for the kilogram? Her answer: ” kay gee”. Then I quickly enquired, ‘is it a capital letter k, or lower case?’ Her answer – after much hesitation – “a capital letter k, a big k”. I politely told her the correct symbol is ‘lower case k and lower case g’; then I added to reinforce it: ‘small letter k and a small g’. Then I went on to complain about the shelf labels I saw, and looked forward to the error being corrected as soon as possible.


  17. Some years ago the offices where I worked were being reconditioned. During the course of the works, the contracting company sent out a briefing update in which they stated that “2 mW air conditioning units” were being installed. I replied to the editor of the briefing respectfully suggesting that 2 mW air conditioners might not be powerful enough for the office and suggested that they install 2 MW units instead.

    This is an example of where it is important to get the upper and lower case letters correct. (BTW, my hearing aids probably consume about 2 mW).


  18. Phil,

    The problem you encountered is fully understandable. It comes from the poor teaching of SI units in schools world-wide. There needs to be a standard teaching method based on BIPM and CGPM style rules. If everyone was taught to these rules, the number of these mistakes would virtually disappear. But, who to your knowledge is?

    A proper teaching of SI units would break the bad habit of mixing prefixes with counting words. Those being taught would learn all of the prefixes and apply them such that no counting words are needed. Thus the it would feel normal to say the earth is 150 Gm from the earth and not 150 million km. We would also see an end to the dreaded kph.

    This push to teach SI correctly has to be initiated from the BIPM itself. The BIPM would need to work with each country’s measurement standards organisations and through them to the national education departments. Without this type of coordination, the problem will continue and just add more confusion instead of consistency and coherency.


  19. A large Tesco store [see above 2017-10-16] .
    I briefly visited the same store again and was glad and surprised to see many shelf labels had the correct symbol ‘kg’.

    I don’t know if all the shelf labels now show ‘kg’ and not the inkorrect symbol ‘Kg’.
    As I didn’t purchase anything from the Delicatessen Counters I don’t know if the ‘Kg’ error that appears on the printed labels has been corrected.


  20. 18 Nov 2017 (above) Phil’s effort to get Tesco to correct its error …
    The printed labels from the Tesco Delicatessen Counters still have the inkorrect symbol ‘Kg’ on them. These labels also show the correct symbol ‘kg’.

    If you visit a Tesco store, you might like to try this test question on members of the Tesco staff – including store managers …
    Show them a printed label from the Delicatessen Counter, and then ask them which symbol is correct, the one with a lower case letter k, or the symbol with the capital letter K?

    Then if you want to engage in more chat, ask when the inkorrect symbol (Kg) is going to be changed?

    Thanks. “Every little helps”


  21. Liam one of the managers at the TESCO store in Redditch, when asked, he did know the correct symbol for the kilogram is ‘kg’; however he wasn’t aware of the problem with the printed labels on their Delicatessen Counters. And he wasn’t aware of the inkorrect shelf labels in the area for laundry detergents eg. ‘Bold Wash Powder, Kg’.

    In another part of the store I saw ‘Tesco cheese everyday value £2.36 per lb’; it did not have a metric unit price (£X per kg).


  22. The Royal Society, & By appointment to HM Queen …
    You might like to think that a lift company which displays ‘By appointment to HM the Queen’, would get symbols correct – perhaps it’s just wishful thinking.
    At the Royal Society’s HQ in London the following symbols are in the Apex Lifts:
    Motor Power: ‘KWh/day’ ‘KW’ and Weight: ‘KG’
    Some good news: Speed is shown correctly: ‘m/s’.


  23. @Mary
    There is little that surprises me these days.
    From their own web site “We are the independent scientific academy of the UK and the Commonwealth, dedicated to promoting excellence in science, from Wiki description of the Royal Society “… the Royal Society, is a learned society.”

    OMG, ‘promoting the excellence of science’, what a disgustingly pathetic effort. Maybe they have some more learning to do before trying to enlighten others (or whatever they do).


  24. More inkorrect symbols, this time on ‘Polyfilla’ on the containers ‘Kg’.
    Polyfilla is a brand marketed by AKZONOBEL.
    [ https://www.akzonobel.com/en ]
    (A major international company)

    I bought a different brand, one which had the correct symbol on the packet (kg).

    IF everyone informed brands that use inkorrect symbols AND also boycotted their products, then companies like Hotpoint, Apex Lifts, and Nantwich Cheese Company, MIGHT eventually get the message and use lower case letter k.


  25. Under the following Metric Views comment – there is reference to AMAZON
    using the inkorrect symbol (Kg) for address/shipping labels.
    On an Amazon website where the weight of a product is shown –
    the inkorrect symbol (Kg) appears to be used most if not all of the time.
    An example:
    Product Dimensions 240 x 240 x 235 cm ; 4.52 Kg
    Shipping Weight 5.1 Kg
    Why is Amazon so ignorant it fails to get the symbol correct?


  26. Joe’s comment about Amazon …
    I followed this up and contacted Amazon; the reply is below:

    This is Praghashni from Amazon Customer Service Department 🙂

    I understand your concern regarding the incorrect symbol for weight specification (‘Kg’ instead of ‘kg’).

    I’ve forwarded this to the concern department, so that this is looked into and updated.

    Thank you for bringing this to our attention.

    Please be rest assured necessary actions will be taken and this will be corrected.

    As always, please feel free to contact us should you have future suggestions, questions or feedback. We have team of experts who takes into consideration each and every feedback of our customers and brings them into practice.

    If there is anything else that we can help you with, please reply to this email, we’ll be glad to see you again and always happy to help you.

    Thank you for being our valued member and shopping at Amazon. We look forward to seeing you again soon 🙂

    Best regards,
    Praghashni M
    Your feedback is helping us build Earth’s Most Customer-Centric Company.
    So, IF Amazon correct this (which they say they will), let us hope other companies, including Tesco with its inkorrectly printed labels on their Delicatessen Counters, will do the same.


  27. These problems with inkorrect symbols falls in line with people treating SI structure like it was USC or Imperial. Using only centimetres, metres, and kilometres for length measuring, grams, kilograms and tonnes for mass/weight measuring and millilitres and litres for volume, etc applies the same limits on SI that are on USC and imperial.

    SI is not just a clone of USC/imperial. It is a whole different concept. When measuring length for example, one picks the unit metre, measures in it and scales the result with a proper prefix. Thus one is not stuck just with three “units”. Distances can and should be expressed in nanometres, micrometres, megametres, terametres, zettametres, etc as a means to keep the values between 1 and 1000.

    Each prefixed unit is not a separate unit to itself but is one unit with a scaling prefix attached. We are still using the metre when we speak of millimetes of terametres.

    SI is inkorrectly taught in schools world-wide. Whether it be the unit symbols or the lack of use of the prefixes. You can’t blame Amazon for getting it wrong, as the korrect unit symbols are not taught in school korrectly to the people making the choice. In fact most people are taught that these are just abbreviations and not symbols. SI is so badly taught most people have no clue that it matters and makes a difference.

    The BIPM really needs to work with every countries standards organisations, who need to work with each countries school systems to assure SI is korrectly taught.


  28. @Daniel Jackson

    As we used to say here in America back in the sixties: “Right on!” 🙂

    Math and science curricula should include correct instruction in the use of the SI year after year to gain full acceptance of proper usage.


  29. Ezra,

    I believe that SI & measurement should be taught as a totally separate course in grade school. Maybe around the 4 grade or so. It should not be taught as a part of maths or science. By the time a student starts to study maths and science they should already be versed in proper usage of SI. Time would be wasted in maths and science classes teaching something that the student should already know and the time in these classes would be better spent teaching the student those subjects.


  30. Re: Amazon’s inkorrect symbols (Philip 2019-08-05). ‘Kgs’ and ‘Kg’.
    Amazon still haven’t corrected their shipping labels and websites.
    I recently contacted Amazon again and was told that they are aware of the problem and do intend to deal with it. I asked, ‘WHEN would Amazon use correct the symbol?’ , I didn’t get an answer.


  31. Philip,

    I think your barking up the wrong tree. Whoever at Amazon is intercepting your complaint most likely is totally clueless about proper unit, symbol and prefix use when it comes to SI. The real problem is they were improperly taught.

    I blame both the BIPM and the national standards bodies for this. The BIPM has a published set of rules and the national standards bodies copy these rules as part of their publications, but it ends there. The BIPM needs to set up a department that will formulate the teaching of proper SI for all regions of the earth and integrate this department into the various national standards bodies to work with the educational bodies in the production of teaching materials and methods for all levels of education.

    SI needs to be taught as a separate subject under the heading of measurement science and would be taught as young as possible and reinforced up the educational ladder until graduation. SI has to be taught as an advanced form of measurement, not just as a copy of imperial/USC where the units are the same but different.

    If this isn’t done, SI will NEVER be taught correctly and never be used to its full advantage. Errors will just continue and in many cases get even worse.


  32. Philip, Daniel

    Is this not just a case of automatic first letter capitalisation? Maybe, maybe not.
    I have just been doing some experiments with this (Libreoffice). Whilst I can get it to auto-correct Kg, KG, KGS, and KGs to kg, and have added this to the auto-correction dictionary, (which I never use anyway), it refuses to correct kw to kW, but just underlines kw as an error and will accept second letter capitalisation.
    Given that SI requires various first and second letter capitalisation (i.e. mW, MW) it would not be possible for the dictionary to decide which of those was correct.
    It really does come down to people using their own brains to learning and understand the correct usage of SI.


  33. BrianAC,

    I ran into this problem with Microsoft Word. For example, it would correct kW to Kw. Switching it back wasn’t easy as it kept switching it back to the wrong symbol. It took a couple of tries before it stopped. Even adding the correct symbol to the dictionary didn’t always help.

    This all falls back on what I keep saying about how SI is improperly taught. Those who write the software are not taught correct SI and don’t know to add the correct unit symbols to the spelling tables.

    Maybe the unit symbols need to be in a separate table that would include other mathematical symbols or even special characters. Symbols, not being words, should not be stuck into word libraries. Symbol libraries can even be expanded to recommend replacing spelled out unit names with correct SI symbols. If a writer uses the word kilometre, the program can suggest the symbol km be used instead. Symbol libraries can also be used to look for incorrect symbols like kph and change it to the correct km/h.

    Users should not be allowed to alter or add incorrect symbols to a symbol library or else the purpose of a symbol library would be defeated. Symbol libraries can be active in such a way that new symbols would be added to the local library when the computer is on line. If a user thinks a symbol should be added to the symbol library they would have to submit a request to the managers of the library for review.

    And as you noted it is not always possible for a program to know the contents and suggest the correct spelling or symbol, but at least a symbol library would weed out most of the mistakes and be more user friendly.

    One other note on spelling dictionaries. There should only be one dictionary for a particular language with all of the spelling variations incorporated. So, if an American wants to use the spelling litre and metre, the spell checker won’t try to change it to liter and meter.


  34. @ johnb78 says: 2015-04-02 at 16:12

    I do like these old threads being re-activated, this one took me on a tour (as many of them do) of the Guardian style guide ( https://www.theguardian.com/guardian-observer-style-guide-b ). Nice to see in there the use of hectare and other things. However, under “billion” (as far as I have got) it has only the US version, no mention of confusion with the UK billion. My issue here though is the use of “1bn litres of water” which I feel is totally wrong, for high volumes it should be Gl, Ml, m² or tonne. Our local reservoirs are listed in 1000’s of megalitres, but the area in acres.


  35. BrianAC,

    The word billion was contrived from the prefix bi, meaning 2 and the word million meaning 10^6. The prefix bi means to multiply the exponent for one million by 2, to get 10^12, thus a billion is correctly 10^12. To fill in the gap from 10^6 and 10^12, that being 10^9, the -iard suffix is used instead of the -ion and we get milliard.

    This is expanded up the line to the other numbers as well. A septillion thus is a 10^42, because the exponent 6 for a million is multiplied by 7 (the meaning of sept) to get 42. A septilliard would be three more zeros added, thus 10^45. A very logical and organised system that innumerates made a mess of .

    You are right in using SI prefixes greater than kilo to apply to litres and other units to eliminate the use of counting words. Megalitres, gigalitres, teralitres, etc make a lot more sense then billions of this or that.

    I think though for the volume of water, you meant cubic metres (m^3) instead of square metres (m^2).


  36. Daniel,
    I did indeed mean m³ (m^3) in my previous post, sorry about that, unfortunately I cannot correct it.
    I also agree that a billion should be 10^12 as it was in UK, not 10^9 as in US and now accepted world wide (except for me). For 1 billion to be 10^9 makes no sense whatsoever, not only makes no sense but is just plain wrong.
    “What happened to the British billion?” Although the question itself missed out a naught it does give some other opinions: – ( https://www.theguardian.com/notesandqueries/query/0,5753,-61424,00.html ) and attributes this to our Chancellor Dennis Healey in 1975.
    Of course this discourse could be avoided by using Giga (16^9 , US billion or Tera 10^12, UK and CORRECT billion). For those, even on here, that disagree with this should reflect on the common phrase “megabucks” and the ubiquity of gigabyte in the mobile phone era, it is no longer just rocket science.


  37. ASDA they cannot get it right. I visited their store in Redditch.
    On some shelf labels there is the inkorrect ‘Kg’.
    I asked one of the store assistants, (possibly aged about 20) which symbol was correct, ‘should it have a capital letter K, or a lower case letter k?’ She said ‘upper case, a capital letter K’.
    I asked her to tell her manager the ‘Kg’ symbol was wrong (inkorrect).
    Later I provided feedback on their website survey: tellasda.com.
    I’ll let you know if I receive a reply!
    I think, Hotpoint are still producing machines with ‘Kg’.
    Tesco; are still producing some labels with ‘Kg’.


  38. I understand Kg is wrong, but as you see a 20 year store assistant thinks it is right meaning the education system is teaching it wrong. This goes back to the BIPM which should but doesn’t involve itself in the proper teaching of metric world wide.

    The good thing though is they are using Kg and not Lb.


  39. As far as education is concerned, one aspect is poor marking schemes which fail to penalise a wrongly written unit name or symbol.
    If teachers told students they would not award marks for ‘Kg’ or ‘kgs’ it would help.
    A simple example to help illustrate this – if the problem is a calculation
    Use of the correct formula [1 mark]
    Correct substitution of values and working [2 marks]
    Correct numerical answer [1 mark]
    Correctly written symbol or unit name [1 mark].
    Some test/exam questions provide the unit symbol in the […answer space..]
    This means the student doesn’t need to write the symbol.


  40. Mary,

    The teachers themselves don’t always know the correct symbols. The BIPM has a style guide for proper spellings and symbol notation and usage but it needs to be converted into a teaching manual for all schools world-wide. There needs to be a separate class on measurement focused on the proper teaching of all SI units and prefixes.

    In addition to proper symbol usage the use of all the prefixes need to be taught and their use encouraged. There needs to be an emphasis on using prefixes other than just centi and kilo.

    Without this emphasis on teaching SI properly, SI will decay into the same mess that is imperial and its sister unit collections.


  41. @Mary

    I’m not sure if this is still the case, but when I was at school in the 1970s and 1980s, we were indeed marked down in Physics if we didn’t write unit symbols correctly. Unfortunately, not everyone studies Physics at school.


  42. BIPM are not in the business of education. The various NMIs are on the periphery of education in respect of their own countries so it is up to the NMIs to liase with the education departments in their own countries. Something that is far worse (in my view) than “Kg” is “KPH” for “kilometres per hour”. Unforunately I do not see that changing until we actually change over to kilometres per hour and somebody who is charged with driving at “100 KPH in a 60 KPH zone” gets a sharp lawyer who convinces the magistrate that “KPH” has no legal standing, hence the charge must fail.


  43. More inkorrect symbols:
    (i) Hotpoint are still producing machines with ‘Kg’ on them [seen in PC World/Currys in Worcester]
    (ii) Brewdog Brewery; I’ve no complaint with the contents of their 330 mL can of Nanny State, it’s really pleasant.
    The problem is on the outside of the can; the details include their symbol for energy shown as ‘Kj’.
    The brewery is in Scotland, [postcode AB41 8BX], I’ll write to the company and alert them to this inkorrect symbol.
    If I receive a reply I’ll let you know!
    Cheers, Philip


  44. Tesco are at it again! Inkorrect symbols.
    I’ve said it before – I rarely visit Tesco, however today I popped into the Redditch store.
    The shelf labels in the dried fruit section (mixed fruit, sultanas, etc), had both the inkorrect ‘Kg’ and the correct ‘kg’.
    I didn’t bother to raise this issue with customer service in the store, however I have mentioned it when completing their online survey. It’s over a decade ago when I first raised this issue with Tesco about their use of the inkorrect ‘Kg’. Will it take another ten years before they stop making this error?


  45. @metricviewer I usually fill my car at the local Tesco petrol station and every time my OCD goes haywire as I see the panel on the side of the pump, which allows you to limit the amount of fuel you are served, which gives you the chance to enter a specific number of “Lts”.


  46. If the label on the beer can says “330 ML”, you might have grounds for complaint!
    On the other hand, where would you store 330 ML beer? That is equal to 3.30*10^5 cubic metres which would half-fill a sports stadium such as Wembley or Twickenham!

    Liked by 1 person

  47. Tesco has been mentioned here a few times. Try going to Tesco’s web site and seaching for McVities. During the ensuing sequence of pages it will change to mcvities, then Mcvities.
    Try a search for AAA (batteries). The result is even more suprising. Some products come up correctly with AAA, others with Aaa – very strange.
    Microsoft Word automatically capitalises the first character of the first word on a new line (not a text overflow). This feature can be turned off but is on by default. Microsoft Excel has a function called “Proper”, which capitalises the first letter of a text string and forces everything following to lower case. These features and functions have their uses, but can be easily used incorrectly.
    The problem with Kg being used instead of the correct kg is therefore likely to be involvement with a computer system somewhere. These systems are managed by boffins working back offices many, many km from the sales floors. These boffins are very expert in their own technical field but many unfortunately seen to be less clued about social life on this planet. It is unlikely that shop managers can reach them.
    At least Tesco can capitalise my name correctly – unlike a certain up-market supermarket which does or does not at will. I complained about this. I was assured this would be put right and I would be sent a new store card with my name correctly represented. The replacement card arrived – but it was a duplicate of the previous one with the wrong capitalisation.

    Liked by 1 person

  48. @ Martin Vlietstra
    I have just browsed for a laser cutting head for my 3D printer. It seems some are 500 mW and others 500 MW. Not sure I can handle a 500 megawatt laser! And that is from China


  49. @Brian
    – Once upon a time … I think I can remember, it was fairly easy to contact ‘Trading Standards’ and they would say -they would investigate a complaint …of course, submitting ‘500 MW’ – AS A WRONG PRODUCT DESCRIPTION – when it is a 500 mW laser – is unlikely to be dealt with.
    – An interesting test case would be to [foolishly] attempt to get 330 ML for the price of 330 mL Cheers!


  50. Metricviewer, We live in a time when correctness is frowned upon and people feel they have the right to be wrong and doing things the wrong way is seen as some example of freedom, free speech and national pride. A complaint arising when we see M instead of m only generates a counter complaint that the context tells us that milli is intended despite the wrong symbol.
    This all falls into my constant complaint that metric is never taught correctly in any school in the world. The incorrect teaching varies not only with unit symbols, but teaching the use of deprecated units outside of SI, teaching that metric is all about 10, ignoring most of the prefixes, etc. In fact teaching metric as a parallel to FFU.
    Teaching metric, requires teaching all of the units that make up SI and to teach how they relate to each other on a 1:1 basis. 1 W = 1 J/s = 1 N.m/s = 1 kg.m²/s³. It requires teaching ALL of the prefixes and to use them, and avoid a lot of zeros. Such as the moon is 384 Mm from the earth, the sun is 150 Gm from the earth. The radius of the solar system is about 150 Tm from the sun (if you include all of the known objects orbiting the sun), the diameter of the Milky way is 1 Zm and the diameter of the observable universe is about 880 YM.
    The BIPM needs to involve itself in creating teaching guides for the SI for the whole world so that everyone over time knows and learns there is a right way to use SI and doing it the right way reduces costly errors and saves lives. Doing it wrong is not freedom nor is it an expression of national pride.


  51. @metricviewer 2021-12-13 at 18:12
    Once upon a long time ago I would say. I tried this a couple of years ago, detailed on this blog somewhere I think.
    Basically it is a total waste of time, effort and blood pressure. The company did take action, just, but nothing meaningful.
    Firstly with Trading Standards you actually have to trade, as with that infamous bunch of bananas the other side like to mention, then prove it was an illegal trade. Best of luck to anyone with that one.
    This issue would be the ‘advertising standards agency’, my opinion of which is not what anyone needs to hear. It is a case of “It is just a description, not a specification”. To my mind a description is (or should be) part of the sales ‘contract’. Other opinions vary.


  52. Yes, good points: Daniel 2021-12-14 at 14:20
    *”never taught correctly in any school in the world” … applies even in ‘good’ metric nations, like for example, Australia, and New Zealand.
    ** Although SI/metric is used in non-STEM subjects like geography, the teaching of skills needed to change, for example, km to Mm to Gm is left to physics and maths teachers.
    *** Occasionally in education you might hear things like ‘ x taught ACROSS THE CURRICULUM’ where x might be ‘health’, ‘social responsibility’ or whatever is the ‘flavour of the month’.
    Probably not a thorough coverage of all aspects of measurement etc.
    **** Has anyone ever heard of ‘measurement’ being a definite subject in a school’s curriculum/weekly timetable?
    Perhaps one small idea to stress the need for a much better coverage of SI [and measurement] might be to include it as a regular feature in comics, magazines, etc.

    Liked by 1 person

  53. @BrianAC – the problem with Trading Standards saying “It is just a description, not a specification” lay in the wording of the the original EU directive which was published in 1971, before the UK joined the EEC (as it was). The wording read: “The obligations arising under Article 1 relate to measuring instruments used, measurements made and indications of quantity expressed in units, whether for economic, public health, public safety or administrative purposes”. This wording was pushed to its limit by the Civil Service who were instructed to find every loophole that they could to keep the plebs happy (and thereby ensure that the government of the day did not lose votes).
    The EU extended the scope of the directive in 2010, but by nifty wording of the Statutory Instrument that implemented the revised EU directive, no minister was tasked with actually ensuring that the extended scope of the directive was implemented in the UK. The goverment was content to wait until somebody actually brought the matter to court (which would have cost the plaintif money). The only scenario that I could see where the matter would have been taken to court would have been a situation where somebody was badly injured or killed as a result of ministerial non-compliance with the directive.


  54. @metricviewer
    You can see a summary of the content of the maths courses in English schools at https://www.gov.uk/government/publications/national-curriculum-in-england-mathematics-programmes-of-study/national-curriculum-in-england-mathematics-programmes-of-study. “Measurement” is taught as a topic within maths.
    Year 2 pupils (7-year-olds) are taught to “choose and use appropriate standard units to estimate and measure length/height in any direction (m/cm); mass (kg/g); temperature (°C); capacity (litres/ml) to the nearest appropriate unit, using rulers, scales, thermometers and measuring vessels”
    Year 5 pupils (10 year-olds) are taught to “convert between different units of metric measure [for example, kilometre and metre; centimetre and metre; centimetre and millimetre; gram and kilogram; litre and millilitre]” and “Understand and use approximate equivalences between metric units and common imperial units such as inches, pounds and pints”
    Year 6 pupils (11 year-olds) are taught to “convert between miles and kilometres”.
    You will notice that pupils are taught to convert between centimetres and metres and between metric and imperial units, but are not taught how to convert between inches and feet, pounds and ounces etc. The real problem lies in the fact that as soon as they leave the classroom, they are exposed to mainly imperial units, so they regard metric units as “something weird that only happens inside the schoolroom”.


  55. Martin,
    I noticed that in the teaching of metric (not SI), there is no mention of prefixes outside of the 6 original prefixes surrounding unity. Where or when do they learn about mega, giga, tera, micro, nano, pico, etc? When and where do they learn the units of newtons, joules, watts, amperes, volts, ohms, farads, henrys, coulombs, tesla, etc?
    That something weird that happens only inside the schoolroom has too be extended to: at the petrol pump, on the weather reports, at the deli counter, on every market shelf, on the job, in the hospital, etc. The only place one is exposed to imperial is in the home, which would indicate their family are all weirdos, maybe including themselves.


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