Measurement muddle – a customary feature of Britain

Ronnie Cohen looks at the measurement muddle in the British Isles during the eighteenth and nineteenth centuries. As our nearest neighbours on the Continent might say, ‘Plus ca change, toujours la meme chose’.

Imperial units such as the acre, stone, pound, ounce, fluid ounce and gallon are still encountered in the UK, even though no longer in official use. They are often heard in conversations and are used, though not consistently, in the media. We take it for granted that these units should have just one meaning but what is not well known is that there were often several.

There have, for example, been many acres, now defined as 4840 square yards, as shown in the following table:

Version of Acre Number of Square Yards
Preston acre 4840, 7840, 9000 and 10240
Hyde acre 10240
Dundalk acre 7040
Barnsley acre 4840, 6084, 7840 and 10240
Cheshire acre 10240
Scotch acre 6084
Irish acre 7840

Body weight is often quoted in stones and pounds in the UK. The stone of 14 avoirdupois pounds is now the only stone that survives. However, many different varieties of stone were used for weighing commodities in the nineteenth century. This is shown in the following table:

Version of Stone Number of Avoirdupois Pounds
Stone of glass 5 lb
Stone of butcher’s meat 8 lb
Stone of iron wire up to 20 gauge 10½ lb
Stone of iron wire above 20 gauge 10 lb
Stone of iron 14 lb
Stone of wool sold by growers 14 lb
Stone of wool sold by woolstaplers to each other 15 lb
Stone of wool, at Belfast and Dublin 16 lb
Stone of flax, at Newry 16 lb
Stone of cheese 16 lb
Stone of flax, at Belfast 16¾ lb and also 24½ lb
Stone of wool, at Darlington 18 lb
Stone of wool, at Downpatrick 24 lb
Stone of hemp 32 lb

There were once three different hundredweights: 100 lb, 112 lb and 120 lb. For each of these, there was a ton of 20 hundredweight. Hence there were also three types of ton: 2000 lb, 2240 lb and 2400 lb. Neither the Imperial ton nor the hundredweight remain as primary measures, the former having been supplanted by the tonne of 1000 kg.

There were also four miles used within the UK: the English mile of 1760 yards, the Scotch mile of 1977 yards, the Irish mile of 2240 yards and the nautical or geographical mile of 6080 feet. The nautical mile has since been replaced by the international nautical mile of 1852 metres for marine and aviation transport. The English mile survives officially throughout the UK for ‘road traffic signs, distance and speed’  – an example of English imperialism?

There were once three different systems of pounds and ounces in use. As well as the avoirdupois and troy systems, there was also the Dutch system. As the 1862 Report (see below) stated, “If you buy an ounce or pound of anything, you must inquire if it belongs to Dutch, troy, or avoirdupois weight.” Confusingly, there are 12 troy ounces in a troy pound. Today, only the troy ounce survives as a primary unit, and then only for dealing in precious metals.

The standard Imperial gallon was introduced in the 1824 Weights and Measures Act in an attempt to emulate the metric system, being defined as the volume of ten pounds of distilled water. It is approximately 277.42 cubic inches. This replaced the corn or Winchester gallon of 268.8 cubic inches, the wine gallon of 231 cubic inches and the ale gallon of 282 cubic inches. These gallons were all in common use in the eighteenth century. For these older gallons, there are corresponding pints that are one eighth of the gallon. Today, the Imperial pint is the sole survivor as a primary unit, but only for draught beer and cider and for doorstep milk.

By the time of the 1824 Act, the United States had enjoyed over forty years of independence from Britain. They were using the corn gallon as their standard dry gallon and the wine gallon as their standard liquid gallon and were not inclined to replace them with the new standard UK gallon. These differences account for the different volume measures between Imperial and those used in the US to this day.

The Report of the Parliamentary Select Committee on Weights and Measures of 1862 described the variety of units that were once used in the UK. With the exception of information about pints and gallons, details of these customary units can be found in the DTI transcript of the report, available here:

Report from the Select Committee on Weights and Measures 1862

An original copy of the report may be found here:

Copy of the 1862 report held by the University of Michigan


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11 Responses to Measurement muddle – a customary feature of Britain

  1. Jake says:

    When I was a child my father used to like to tease my friends by asking them: 'What is heavier: a pound of feathers or a pound of lead'? Looking at your definitions of a 'stone', I am not so sure now that his answer was necessarily right! Perhaps it depended on the city where the feathers and lead were sold and who was doing the selling, or whether the dealers were actually selling the goods to each other. It just goes to show what a hotch-potch of units the Imperial system was and how thoroughly unsuited it is to modern life. As to whether the English mile as used in the UK for ‘road traffic signs, distance and speed’ is an example of English imperialism, I think you could be forgiven for thinking that. Why does the UK hang on to this anachronistic unit on the roads? Is it better than the metric units that are taught in UK schools for all other measurement purposes? Does it make calculating journey times or costs any easier? I don't see how it does. If it were only the 'mile' that were on road signs, perhaps one could grin and bear it, but the use of the mile perpetuates the use of yards, feet and inches on these signs as well, depriving people in the UK of the possibility of seeing and internalising the metric units they have learnt at school and of gaining familiarity with them through everyday exposure and use.

  2. John Frewen-Lord says:

    To further Jake's comments above (and in particular calculating journey times), the use of the same unit of imperial measures for distances in terms of what are often very different actual measurements, can be distilled down to the following (which can be used as very effective arguments in favour of metrication of road signs in the UK). Advocates of retaining imperial measurements often promote the speed of 60 mph as being one mile per minute, saying that the metric system affords no such easy method of equating speed with distance.

    On the contrary, metric is far better - let us count the ways:

    Walking - a good brisk walking speed is probably around 6 km/h (which is also 6000 m/h. Divide by 60 (the number of minutes in an hour), and you have a walking speed of 100 m/min, which is very useful in calculating times over typical walking distances.

    Cycling - a typical average cycling speed is 20 km/h. A journey to the local shops, or even the distance to work if you live in a city, might be 5 km, which will take 15 min, or 1/4 hour.

    Local car journeys - if 60 mph equals 1 mile/min, then so does 60 km/h equal 1 km/min. 60 km/h is a typical urban average speed over a mix of urban 2-way roads and urban dual carriageways, with speed limits in the 60 to 80 km/h (40 to 50 mph) range. Thus a journey of 12 km can be expected to take 12 min. Easy!

    Long distance car journeys - these are usually measured in terms of hours rather than minutes. A typical average speed, over mostly motorway and rural dual carriageway roads, will likely average 100 km/h. Thus a journey of, say, 400 km (the distance for example between my home and that of my cousins on the south coast) will take around 4 hours (which it usually does, unless traffic is particularly heavy).

    High speed driving - most motorway driving is usually a little above the UK national speed limit of 112 km/h, at around 120 km/h, which equates of course to 2 km/min. The next exit is 12 km away? Get there in 6 min.

    And, as has been pointed out many times. metric odometers simplify equating distances recorded by your car and those seen on metric road signs. Next junction 800 m away? Your car odometer will record it as 8 x 0.1 m - something that is not possible with imperial odometers, where the miles are recorded in 10ths, but the road signs show fractions of a mile, or yards, or llath, or feet, or whatever.

    Ronnie's article shows how imperial measures have been simplified over the years - but not to the extent that the US (the only other major country still using non-metric measures) and the UK can actually talk the same measurement language. All current UK legal imperial units are now defined by their metric equivalents. The time has come to finally drop imperial altogether.

  3. Ezra Steinberg says:

    Thanks to John Frewen-Lord for his most informative post! 🙂

  4. eric says:

    Mrs Thatcher exempted the mile, ounce for gold and if I remember correctly the pint from being replaced with metric units. With UKIP doing so well Britain has no hope of ever going fully metric.

    The majority of US customary units were redefined in terms of the meter and the kilogram with the Mendenhall Order of 1893 and, in practice, for many years before.[1] These definitions were refined by the international yard and pound agreement of 1959.
    So what is wrong with the odometer showing 800 m, looks to me like, why make it simple if you can make it complicated?

  5. Ezra Steinberg says:

    It looks like perhaps the stuff I've read recently about the demise of Fahrenheit (finally!) in the UK may be true.

    I was listening to the BBC World Service tonight (as usual) when a segment came on about the history of preserving food and the development of the modern cold storage supply chain.

    Naturally, the people in the segment had to mention temperature. I was pleasantly surprised to hear all the people being interviewed talk about temperatures only in degrees Celsius. On top of that, they mentioned only the numeric values, not even bother to say "degrees Celsius" or "degrees C" or even just "C". This implies to me that they believe it is so obvious to always use "degrees Celsius" to specify temperature that they don't need to bother to qualify it in any way.

    So, the various temperature bands used at the new port facility in London were referred to by the manager being interviewed as "plus 2", "minus 15", etc. Quite encouraging!

    On the other side of the coin, there was also the usual use of "miles" for distance (with no mention of "kilometers" even as a supplementary indication). Oh, well.

    But at least "degrees Fahrenheit" seem to have gone the way of "fathoms" and "shillings"! 🙂

  6. Alex says:

    You clearly didn't watch Top Gear last night Ezra... with Mr Clarkson in Australia gleefully pronouncing the temperature in degrees Fahrenheit (and the size of a farm in acres). Editorial preference over sensibility is alive and well at the BBC.

  7. BrianAC says:

    Top Gear is another programme I have stopped even recording. Clarkson would probably have done that deliberately having been faced with metric spoken in English everywhere, possibly even taking the team by surprise, thus 'fuelling the fire' of their normal stupidity. I just hope my Formula One does not have to go the same way this year, that is one of the few programmes I can still watch. I did note with glee that in the US a TV station gave the snow depth as 'one and a half dogs worth', apparently as a joke at the expense of the BBC!

  8. Bob says:

    I remember reading a book called "Ripley's believe it or not" which said a pound of feather's weighs more than a pound of gold. You can read it here:

  9. Bob says:

    British local government websites still quote prices per stone. See:
    "prawns...£30 per stone"
    "winkles for around £5 per stone"

  10. Jake says:


    Since reading your posting, I have been trying to work out what your point was. The local government websites aren't exactly 'quoting' prices 'per stone' as local government is not in the business of selling the goods in question. (If I 'quote' someone a price for something, I can reasonably be expected to be the seller of the goods or acting on behalf of the seller.) To me the references (and one is in a document that is already several years old) imply that a certain price or price target per imperial weight was indicated to a government official by the fishermen. This simply underlines the point of the article that archaic units of measurment still swirl around in Britain alongside the legal units and that there is indeed a measurement muddle.

  11. BrianAC says:

    Let me introduce the decimal stone! I wonder where they got the decimal stones scales from.
    Is this the daftest set of conversions yet? Quotes from a slimming pill advertisment.

    "Dieting resulted in shedding at least over 1.5 stone in just a month for our readers!"
    "I wanted to lose 1.6 stone for my wedding."
    "I now weighed under 10.7 stone for the first time in years!"
    "Plus I still managed to lose another 0.7 stone, putting me at an unbelievable 1.4 stone of weight loss, in just 2 weeks."

    Full marks must surely be given for the novel use of decimal stones. I do wonder which side of the fence that irks the most?


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