We look at some of the consequences when there is more than one option for supplementary units on product labels.
In the UK, metric is the primary system of measurement for all purposes except for draught beer and cider, doorstep milk, and of course road traffic signs for speed and distance. It must always appear on those product labels that are required to show quantities. Labels may also show other units, so what are the rules for these ‘supplementary indications’ (SIs)?
The late, lamented LACORS provided advice on SIs as long ago as 31 July 1995:
“Neither the (EU) Directive nor the implementing UK legislation offer guidance on either the appropriate units to be used as supplementary indications, nor upon the accuracy of the indication in absolute terms.”
In other words, SIs can be in any units except metric and do not have to be accurate. That said, the UK Quantity Marking and Abbreviations of Units Regulations require that the supplementary indication should be in an equivalent type of unit – using grams and ounces together is OK, but using grams and fluid ounces is a no-no. Furthermore, there is a general requirement that product labelling should not deliberately mislead.
Since the 1960s, the pound and the foot have had the same meaning on both sides of the Atlantic (with a few unimportant exceptions pointed out by John Steele in a recent comment on MV). But this happy state of affairs does not apply to non-metric measures of volume. The US pint is less than as the UK pint (drinkers beware), and the US gallon and fluid ounce differ from their obsolete British counterparts. Confusion over mpg frequently traps the unwary, appearing to be about 17% less in the US, but what about confusion over fluid ounces on product labelling in the UK?
Some products sold in the UK use the US definition of the fluid ounce of 29.6 mL, presumably to meet US labelling requirements. The UK fluid ounce is 28.4 mL, so labels showing US fluid ounces are acceptable in the UK as the buyer will receive at least as much as expected and possibly more. (The opposite would be true were UK labels to show US quarts and pints. This would clearly be unacceptable and accordingly such labels appear rarely in the UK, and then usually on products intended to be sold in both countries with US measures clearly distinguished).
Examples of US fluid ounce labels are not difficult to find. A quick look around the shelves at Tesco recently revealed two containers of cream next to each other where the metric quantity was the same but the SIs differed. One was labelled “300 ml 10 fl oz” and the other was labelled “300 ml 10.6 fl oz”. Consumers might ask, “Are they the same size or is one bigger than the other?”
While such product labels may be legal, the use of two different fluid ounces can limit the usefulness of the information. For example, although recipes published over the past 25 years have usually been metric or have metric alternatives, cooks of the old school, accustomed to adding so many fluid ounces, might be well advised to measure rather than rely on the label. Better still, how about replacing those old cook books and scales with metric or dual ones?
Another mistake that further reduces the value of fluid ounces on UK product labels is the fact that some products contain incorrect conversions, even after allowing for rounding, using either the UK or US definitions. There are, for example, some aftershaves sold in the UK that use a conversion factor of 30 mL per fluid ounce.
Possibly, the most annoying occurrence of the US fluid ounce is its use as a description rather than a measure. That “16 oz grande” in Starbucks – just how much coffee am I getting? Actually, it will be about 473 mL.
Clearly, multiple definitions of measurement units are not helpful. Supplementary indications are likely to be with us for many years to come, but perhaps producers can be encouraged to abandon fluid ounces and use only millilitres and litres – the litre is the same all over the world unlike the fluid ounce! However, it may take a change in US labelling laws to allow metric-only labels before we see a further decline and the eventual disappearance of supplementary indications.
27 thoughts on “The use and abuse of fluid ounces”
The 30 mL definition of the fluid ounce is defined by the FDA for use on nutrition labels, where quantities of energy, fat, etc. are stated per fluid ounce. They have a similar definition for the ounce (mass) of 28 g exactly.
A solution is for the UK to join us and embrace USC units. On another note, a problem in the United States with fluid ounces is with taking medications. Although dose cups sold with cough medication has both mL, fl oz and sometimes drams there is confusion. In California, milk products can only be sold in pint, quart, and gallon sizes with dual SI labeling.
You may certainly be seeing US fluid ounces used by mistake. I would like to present a case that you are NOT seeing them as a result of a plan to produce a package salable in both the US and UK. I think there would be issues with those packages complying with US net contents declaration and nutritional information.
US Net Contents must be declared on the principal display panel (PDP). For a rectangular package, that is the obvious front where the manufacturer’s logo, product name, photo, etc appear. For a roughly cylindrical package it is the 40% of the circumference containing the same information, centered on the identity declaration. I need a more frontal view, but I think on those packages, it is too far to the side to be within the 40% of the circumference obvious “identity” face. Also, the one on the right does not have adequate “white space” around the net contents zone (equal to letter height) and the left one is at least marginal on the lower edge.
The nutrition information is too fuzzy to read, but it does not appear to closely match the required US style, and may not match our concept of serving size, which must be declared according to FDA rules.
I don’t know how to include this inline, but a link to some US dairy products (unfortunately all in rectangular cartons) showing style of net contents on PDP, and nutrition panel:
(all four faces are shown for each example. Note that some products have two identical PDP faces)
As the cartons in your example would probably not be salable in the US, any fluid ounce mistake presumably has some other cause. I would love to see us allow metric-only labelling, but I am not convinved it would help your problem.
Alternate theory: Could that tri-color flag I see on one carton have anything to do with not precisely understanding the units?
But wait, don’t you buy your yoghurt in megaliters and your candy in kilogauss? No?
I was a bit suspicious when the shampoo bottle contained 250 ML of shampoo, all of which I was able to hold in my hand. Man, I must have become superstrong since I ate that highly magnetic candy. All 0.5 KG of it. How about distances in kilomolar, KM, don’t that just make your day? Ah you know, I’m running 5 KM today, it helps me concentrate for that test later.
They might not be perfect, but neither are we.
I am glad to see that dual labelling on products is the exception rather than the rule these days.
As for ounces used for drinks, it was ony recently that I discovered that when a restaurant menu describes a soft drink served “in a 16oz glass”, it is not referring to the weight of the glass.
P.S. Don’t you think that “SI” is an unfortunate abbreviation to use for “supplementary indication”?
US nutrition labels are not per ounce, etc. The fat, salt, protein etc is stated per serving size. Under some circumstances, the serving size is dictated by FDA (many classes of product), for some it is at manufacturer’s discretion, especially when only a few servings in the package). The serving size is described in both metric and Customary. It is likely not well understood, but the metric is correct and the Customary is rounded or approximate.
The actual analysis is done on 100 g (or mL) samples, and the stated values are those results times stated metric serving size over 100. The Customary must be rounded in accordance with FDA rounding rules. Also the actual numeric values must be rounded in accordance with FDA rules. (I’m not defending either of those rounding rules; I have some issues with them, but they are the rules).
It should be noted there is no connection between the nutrition rules and the net content rules as to acceptable rounding or accuracy. When dual labelled net contents are specified, the values are converted to the same unit, using either exact conversions or at least six significant figures, the larger claim determined, and tested against a lot sample which must meet or exceed claim.
If I applied US law but Imperial ounces to the photograph, the 10.6 fl oz bottle must contain at least 301.18 mL (contents may never be rounded up) so it might be larger than the 300 mL bottle, but there is no way to tell how much either might exceed its required minimum.
I was referring to this. In Title 21 – Food and Drugs from the Code of Federal Regulations, it states:
“(viii) For nutrition labeling purposes, a teaspoon means 5 milliliters (mL), a tablespoon means 15 mL, a cup means 240 mL, 1 fl oz means 30 mL, and 1 oz in weight means 28 g.”
I was mistaken about the use of serving size, but that means where the serving size is stated as a multiple of (fluid) ounces, then it should use those definitions, rather than the normal definitions of 1/16 pints or pounds.
I agree with Peter K above. In my (limited) experience, supplementary indications are disappearing slowly. For instance, I’m very sure the label on my favourite marmalade jars said “454g/1lb” until recently. Now it just says “454g”. Indeed, a quick look along the jams and marmalades on sale in Tesco recently showed most with metric-only labels.
As far as I can see, this strange business of US Fl.Oz appearing as “Fl. Oz” markings on goods only seems to apply to cosmetrics and toiletries, and then only on “branded” items, never supermarket own-label stuff. And it always seems to be appearing on produce that you’d expect might be targeted at the US, or from companies owned by the US (like King of Shaves, Gillette, etc).
I’d assumed it was so that the same packaging could be used in both markets, but the comments above from U.S commentators seems to dispute that. Interesting. Maybe the U.S companies didn’t 100% understand British labelling laws, and just never realised that they could get away with metric-only markings over here. And maybe they didn’t know that a U.S. Fl. Oz isn’t the same as a British one.
I absolutely agree you are quoting it correctly. However, the wording is a bit misleading. What it REALLY means is a serving of 5 mL will be CALLED a teaspoon, 30 mL will be called a (fluid) ounce, 28 g will be called an ounce for purposes of the stating the Customary serving size.
A curiosity of the US law is that “fluid” or the symbol is optional because the metric marking in milliliters makes it “obvious” (really??) by association that volume is meant. Some manufacturers use it, some do not. Cross-labelling (one unit of weight, the other of volume) is not permitted.
My comments were primarily directed to food, where nutrition labels are required and have somewhat different formats. I think a common package would be more feasible on toiletries and cosmetics (and other non-food products). It would be necessary to lay out all the little details on letter height, case of symbols, clearance around the net contents zone, location of declaration, etc. Sorry if I over-generalized.
I’m not saying we have 100% compliance, but US labelling law requires correct case for SI symbols, and provides an exemption to the letter height rule for lower case SI symbols. Otherwise the required letter height is based on capitals if all-caps is used apart from SI symbols, otherwise x-height (law actually cites a lower case o) if mixed case or lower case is used. Letter height requirement is based on area of principal display panel.
(If anyone cares about all these details, USMA site has excellent summary and links to relevant sections of US CFR.)
This topic has been raised before but the real reason that supplementary indications persist across Europe is American businesses insisting on their retention for imported and exported goods. The UK retail sector also have an interest because of the lack of a clean changeover domestically.
There is little prospect of their demise until the US makes sufficient progress to tolerate metric-only labelling and the UK recognizes that people will not move on until imperial indications are removed.
Fluid ounces are one thing that resist metrication in Ireland. Smoothies and other drinks sold in cups are almost always measured bij that unit. The Irish fast food chain Supermac uses it (US or Imperial, that is not indicated), but American fast food chains like MacDonalds mark their cups in litres! Drinks sold in bottles are metric, so is milk in milk cartons. I do not understand why the fluid ounce won’t go to oblivion in Ireland.
Re: Han Maenen’s post
I contacted my personal contact in Ireland about the issue of fluid ounces in Ireland and got this reply:
“I had not heard about this use of fluid ounces at Supermac, so I went down to my local Supermac here. The drinks are labelled as Regular, Medium & Large. There were no other indications of size either in ml or floozies.”
“I doubt if many people here are familiar with fluid ounces, as I haven’t come across this unit myself, nor have I heard anyone referring to it. The Imperial unit that is the most resistant here is the pint – but only in the sale of beer in bars (bottled beer, milk & pretty much every other liquid is sold in liters or ml). Draught beer is still sold in pints (Imperial pints), and it is one of the few exemptions to metric labelling regulations (others being specialist stuff like feet in aviation). ”
“The ‘pint of plain’ will probably be the last imperial unit in trade to be done away with.”
If Han or anyone else has photos they can put on a web site or other sharing platform with instances of fluid ounces on the label on a product sold in Ireland, that might be helpful.
Reading this I see a fair amount of irony… the over-riding reason why the European Units of Measurement law continues to allow supplementary indications is to allow products to be sold in both European and US markets without expensive re-labelling, however it is clear that other labelling requirements such as nutritional information means that manufacturers have to print different labels for different markets anyway which very much makes the whole argument redundant.
That being the case I have myself also seen a move towards single unit labelling on UK-produced items, McCain oven chips are one example which always used to be labelled “1.81 kg 4 lb” but are now merely “1.81 kg”. However despite the clear labelling the consumer still isn’t helped by the fact almost every other brand are sold in 2 kg packages but look about the same, great for those who just compare the price of a “big bag”.
I’ve also had experience in recent years of the continuing use of the “fl oz” on US items that find their way to the UK, particularly cardboard cups used by takeaways for drinks. Until a year or so ago some branches of Subway insisted on pricing their soft drinks in using that unit but because they weren’t selling “per fl oz” it was deemed legal. In the same way I was recently told by a friend who’d worked in Starbucks that one thing they learned on the drinks size was the phrase “venti is twenty”, meaning 20 fl oz. Most of us generally see this as a “large” but it’s clearly a good way to hide the use of a US unit.
Brief article about the push to weigh infants and children only kilograms in the USA. This makes me wonder how the NHS is doing in that regard (actually, weighing *everyone* only in kilograms).
Going metric: The Arizona Department of Health Services e-mailed a link about a movement to start weighing pediatric patients in kilograms. Seems odd, given how much America hates the metric system. But if you see it on your kid’s chart someday soon, you’ll know why: pediatric medications, unlike adult medications, are administered based on a child’s weight in kilograms. Docs fear kids could get the wrong dose if the conversion from pounds to kilograms goes awry.
Position paper of the Emergency Nurses Association:
Click to access WeighingPedsPtsinKG.pdf
“Of all the ways that pediatric patients can be harmed during treatment, medication errors are the most common and most preventable”.1 Developmental differences and dosing complexities unique to pediatrics put children at high risk for both medication errors and for serious consequences as a result of these errors.1,2 In contrast to adult medication doses (which are often standard, unit-doses), pediatric medication doses are weight-based; based specifically upon the patient’s weight in kilograms. Determining the correct dose of a pediatric medication typically requires multiple calculations, and adult concentrations of drugs must often be diluted for pediatric administration. A 2009 analysis of 479 medication errors involving wrong weights discovered that over 25% were due to “confusion between pounds and kilograms”. Weighing and documenting pediatric weights only in kilograms has been repeatedly recommended in the literature as a strategy to decrease medication errors not only in the emergency department, but throughout the inpatient encounter.
It is the position of the Emergency Nurses Association that:
1. Pediatric weights only be measured and documented in kilograms .1,4,5,6,8,9
2. Scales used to weigh pediatric patients only be configured to record weights in kilograms .5
3. Pediatric weights are recorded in a prominent place on the medical record.8
4. Electronic medical records are standardized to allow only kilograms for pediatric weight entries.
5. The pediatric patient’s actual weight is considered part of the mandatory nursing assessment unless they require resuscitation or emergent stabilization.
6. For the pediatric patient who require resuscitation or emergent stabilization, a standard method of estimating weight in kilograms is used (e.g., length-based system).6,7
7. The pediatric patient’s weight in kilograms is included in any inter or intra disciplinary patient handoff report.
It is my understanding that all records on the NHS database are in kilos. The NHS is metric internally and weighs new born baby in kilograms. Furthermore, follow up visits from health visitors also quote any weight gains in grams. Given the number of NHS personnel who are from overseas, this also means that all medical staff are talking the same language. So far, so good. The problem is that the majority of the UK public do not seem to want their new born babies weight in metric measurements as they claim that no-one can understand it. They say that no-one knows that 2 kg is underweight, 3 kg is healthy and 4 kg is large. It doesn’t take long to get your head around it – but that’s the attitude that we are up against in the UK. They see metric as being for the scientists, geeks and pedants (and in my opinion quibbling over kmph or km/h, kg or Kg etc all add to this image of metric being for geeks)
Not sure where to post this but there was an interesting conversation on the Radio 2 Breakfast Show with Chris Evans, Monday morning September 10th. You can hear it here:
http://www.bbc.co.uk/iplayer/episode/b01mk0sw/The_Chris_Evans_Breakfast_Show_Robbie_Williams_joins_us_for_Breakfast/ – at 2:25:00 until September 17th but I will summarise it thus:
To those who don’t know, Chris Evans show on Radio 2 is the UK’s most listened to Breakfast show, with an audience of over 9 million.
Chris Evans was speculating with his sports reporter Vassos Alexander, on Andy Murrays’ chances against Novak Djokovic. Chris was wondering how much Djokovic weighed, to which Vassos replied “76 or 77 kilos”. Chris, a frequent user of kilos to refer to weight, replies “That can’t be right, I’m 82 kilos” – reference then turned to Djokovic’s height where we return to Imperial “He’s about 6 foot 5 isn’t he?”. Vassos quickly corrects this to 6 foot 2 inches, pointing out that this is the same height as Chris Evans himself. After checking the stats, Evans confirms ‘Djokovic’s weight is 80 kilos
Things then turn for the worse when traffic reporter Lynne Bowles asks what all this is in ‘real money’, which starts Chris converting on air. Proclaiming there is “2.2 lbs to the kilo, so thats what 160……. and another 16…… so thats 176 pounds……” Evans then attempts to perform more mental arithmetic before advising Bowles “divide that answer by 14 and that will give you stones and your Imperial thing”. Bowles comments “you see, this is why were taught long division at school” while Evans quickly arrives at the answer: 12 stones 8 pounds
It was all good fun – but a clear indication of the daily muddle we face every day in the UK! Chris Evans is the same age as me so its good to hear him use kilos. But like many Brits he reverts to feet and inches for height. Lynne Bowles was born in 1963 and so would have been no more than 11 when Imperial measurements were taken off the syllabus in the UK. She should know better! Mind you , she had worked with Terry Wogan for many years, in the same morning show slot. Wogan, as many UK readers will know, is a curmudgeonly character and his show attracted many similar minded listeners, many of whom reflected Wogan’s ‘Little England’ mindset
The two cartons of cream are clearly both Tesco own-brand produce. They carry the same ‘seal’ branding, they have the Tesco-only percentages-of-RDA markers (Tesco refuse to use the traffic-light method of informing customers that were recommended by a commission). It may be of French origin but the consistent style suggests packaging design in-house by Tesco.
To be honest, I think this is just a case of poor rounding rather than choosing to use the US measurement.
I certainly missed the obvious. That is soured cream (we call it sour cream). In the US, it must be sold by weight. It is over the viscosity that we consider to be liquid. See example on this page. (It is an enormous tub, 3 lb, but it was the clearest image). I have never seen the net contents of sour cream stated as volume before. So it certainly isn’t “labelled for sale in US.”
The BBC mistakes Customary and Imperial fluid ounces in this story about beer sales to an American Indian tribe. A can of 12 US fl oz is 354 or 355 mL.
“The four White Clay beer stores named in the suit sold the equivalent of 4.3 million 12oz (0.34 litre) cans last year.”
To Ezra Steinberg,
You are partially right about Supermacs. They do sell their drinks in small, medium and large sizes indeed. But a closer examination of the cups they use reveals what unit they use. Yesterday I had a medium Coke. After I emptied the cup I turned it upside down and saw a red text on the inside of the rim. It stated that the cup was made in Britain and that it contained ’16 oz’.
I was in a Frankie’s and Bennie’s restaurant tonight. In the UK.
I asked how many Millilitres was in the Pepsi Cola and they said “16 ounce “.
They could not tell me how many millilitres that was.
They said they did not know.
I asked other people what they thought it was and they had no idea either.
My grandfather used to talk about Fluid Ounces.
What’s going on ?
whilst completely ridiculous that a restaurant would use such measures for drink – the only liquids I know which people still measure in outdated measures are beer, milk, and sometimes cream (I think Elmea still use a 10 fl oz pot) –
16 oz would refer either to 16 US oz at about 473 mL (1 US Pint)
or 16 UK oz at 454 mL (3/4 Imperial Pint)
this is the problem which arises when countries use measures with the same name but different values! The US Gallon being defined as exactly 231 cu in – giving it a volume of about 3.79 L – and the UK Gallon being defined as exactly 4.54609 L. Then the subdivisions are different and of different sizes too! Think how much easier all of this would be if we all used the same measures – especially when referring to fuel economy (compare mpg in the UK and US, L/100 km or km/L have the same value everywhere!)
I really do feel for those that live in this halfway house. I am old enough that at least I know what they are talking about, even if they themselves do not. Charlie missed out that it could also be a pound, a solid 16 ounces.
I have to admit confusion myself, as I do not recall during my childhood, nor young adult hood that fluid ounces were really used that often. Back then I considered them as some ‘strange American measure’ used by, predictably Americans and their funny coffee bars and things. Stones also were never, as I recall, used for anything other than human body weight, certainly not for inanimate objects that BBC south east seems to use them for today.
Unlike Charlie though, I would have no real idea what they meant, except to go back to basics.
Let’s see how daft it gets, from a septuagenarians point of view in 2015. 16 ounces? quick as a flash, that’s a pound, about 500g. No, its a coke, American, probably a pint then. How big is a American pint? No, this is UK surely its UK 16 fl oz, flummoxed now, that’s 16/20 of a pint, right? (this is without red wine BTW, that becomes a bit more difficult), OK 4/5 of a pint, convert that to x/8 to make it into a gallon which I have learnt is about 4.5 litres. Just remembering that milk is 2 pints, 1.136 litres. That almost helps, so 1 pint is 450 ml, 4/5 of that 4 x 90 =360. So my guess is 16 ounces = 360 cc (CC = old way). That is a long way from Charlie’s 3/4 pint = 454 ml. Anyone else care to try?
Sorry, to me this is just so BL***Y stupid, why not just use something we (septuagenarians included) can understand. NOTE: – I was NOT taught to convert from daft to sensible and back, I do not want to know, nor do I care what a stupid ounce is. I was taught however, through many hours of torture, how to convert miles, yards, feet and inches into inches, then cwt, lbs and ounces to ounces, then having got all that wrong and spent another hour working out the subject of the question, converting it all back to miles, yards, feet inches, cwt, pounds and ounces.
My god, you youngsters have no idea just how hard it all was. That leaves out 12 pence to a shilling, 20 shillings to a pound. And there are those around that even want those back again.
though unlikely, they could also be using 16 troy oz; (1 lb 4 oz troy) which would give a total of 497.655629 mL which is 40 mL away from the 454 mL possibility and even more so than 360 cc!
For the record regarding understanding; I’m only 21, but had to learn the relationships of the imperial units when teaching about Anglosphere culture and history in Spain last year. I never actually learnt equivalences or anything between imperial and metric at school. I’ve ended up in the very situation UKMA seeks to abolish – I really lack a general understanding of either imperial or metric because in life I’m unable to use either one or the other consistently. (It says something about the UK education system that in France I had to ask a frenchman how many millimetres there are in a centimetre – nothing too stupid I just couldn’t remember if it was 10 or 100.)
The many different ounces we have discussed in the last three/four comments alone indicate why it would be much easier for us all to use one system, a millilitre is the same in every country and it really is time the UK (and US) went the full 8.2296 m with regards to metrication!
American style: I know my gallon is 128 fl oz which is irrelevant and yours is 160 fl oz, so 0.1 gallon. The UK gallon is around 4.5 L so around 450 mL. Once I look up your gallon, 454.609 mL exactly, by definition.
The confusing situation of having two slightly different fluid ounces is a very good reason for abolishing the Imperial fluid ounce and dealing only in litres and millilitres. The UKMA should make this point to the Government and to the consumers’ associations, both public and private.
The late Margaret Thatcher might have saved the mile and the pint for England, but she didn’t say the fluid ounce needed to be saved.
Yes, the troy ounce. Now that one I do know as that is how my hoard of gold bullion is weighed, and I don’t want to get that wrong.
I made the point during a string of pointless computations how easy it is to get one wrong (1.136 / 2 =450, really!) John Steel says ‘once I look up your gallon’ Just how do you do that in say, the Arctic, in the Saudi desert or even on the moon. I lived and worked in the real world. I was first confronted with kPa in the mountains of Papua New Guinea. No looking that up. It surfaced again in the Saudi desert. I have never used PSI since I realised the kPa / bar relationship, how simple it was and the problems caused by simply not knowing ‘AT THAT MOMENT TIME’, that is when it can kill you, in real life situations. OK, those on the other side will say that is why we need to know both. RUBBISH, it is not both, there are others (US, China Japan, Myanmar as a few, all have there own system, why are they not taught then?)
Charlie makes the point exactly, we do not get to understand either system (although I would argue Imperial is not a system, nor can it ever be properly understood!). I too had the French, not so well educated, running circles round me as far as spacial awareness and the understanding of length and distance, and I thought I was pretty good.
The point is clear, but why don’t those in power do something? Is it just power over the masses, let them eat cake?