United Kingdom and Commonwealth countries


As early as 1215 the Magna Carta required for England a uniform measurement system

"Let there be one measure for wine throughout our kingdom, and one measure for ale, and one measure for corn, to wit "the London quarter"; and one width for cloths whether dyed, russet or halberget, to wit two ells within the selvedges. Let it be the same with weights as with measures."


Let us jump over a few centuries and reach 1824, under George IV reign: the Weights and Measures Act establishes the famous Imperial Weights and Measures system. Coherent, albeit not very simple: three base units, pound "avoirdupois" (symbol lb av., derived from the Florentine libbra), yard (yd) and second; two standards, a brass rod with golden tips for the yard, and a platinum cylinder for the pound, both deposited at the office of the Commons; the unit of volume, gallon (gal), was defined as the volume of 10 pounds of distilled water at a temperature of 62° Fahrenheit. Why "imperial"? certainly because the system became immediately legal in the United Kingdom as well as in all countries of the British Empire. Why "avoirdupois"? because around year 1300 the London merchants had adopted a system of weights then used in France under the name of aver de peis ; incidentally this avoided any confusion between the pound avoirdupois and the troy pound (lb troy): Troyes was a city in France famous for its medieval trade fairs. Not only France did invent the metric system, it also inspired the British system...

But there was a challenger: the metric system.

Our British neighbors, as usual pragmatic and opportunistic (the wait and see policy...) kept an eye on it since 1790: that year Talleyrand had proposed a cooperation in the development of the new system; Sir Riggs Miller had forwarded the proposal to the Commons. A first step in a love story that proceeded for hundred and fifty years before naturally concluding by pairing: the 1963 Weights and Measures Act defined the yard as (exactly) 0.914 4 meter and the pound as (approximately) 0.453 592 37 kilogram. Those who in Britain desperately stick to the imperial system do not know - or do forget - that their inch and pound are now nothing but decimal subdivisions of the meter and kilogram... The same people are certainly not very enthusiastic about the prospect of the (sterling) pound becoming a subdivision of the euro!

As a European Union member since 1973 the United Kingdom adopts SI.

Now comes the great metrication period: in a 1972 white paper the government takes stock of the progress achieved and "confirms its support for an orderly transition to metric units for the country as a whole". By 1970-71 electrical cables industry, aircraft construction, glass production, were all fully metric. The 1973 Commonwealth Conference recommends the adoption of SI to all its member nations. In 1974 use of imperial units is restricted in education whilst metric units are favored. Next year Royal Mail and National Health Service are metricated. In the following years food industry, coal trade, bakeries, turn metric. In students' final exams only metric units are allowed. First gasoline sales by the liter occur. Even elderly people associations no longer oppose metric units. Finally in 1980 selling milk by the liter is made legal.

There is opposition, especially from anti-European persons.

Early 2000 some newspapers gloated over certain parochial grocers and butchers who refused to sell beans and mutton chops in any other unit that pound; every big cause generates its martyrs... The most popular of these metric martyrs was certainly Steve Thoburn, a grocer in Sunderland, north-east England; after having - somewhat harshly - refused to convert his scales to display load in grams in kilograms, he had eventually been arrested and condemned to six months of imprisonment with remission of sentence. And to pay trial costs, some 60 000 £, mostly covered by a number of persons fanatically attached to ancient measures. Will these people pay the 500 000 £ needed by Steve Thoburn for his appeal? Because, as a real martyr, he lodged appeal in response "to thousands of true Britons who asked him to keep fighting the domination by Brussels".

Australia adopts SI in 1970.

Everything perfect, thus? Well, there are still some failures. For instance this carpet shop offering a "4 meter by 10 feet" carpet; real estate transactions still legally use acres and square feet; the cricket game pitch still is 22 yard long; threads par inch measure cloth texture; most people, with the exception of youngsters, still give their size in feet and inches, their weight in stones; weight of new-born babies is still given in pounds - just to be able to make comparisons with babies of previous generations; in clothes shops some vendors make it a point of honor of using the former system of sizes; in many cook books recipes feature pounds and ounces - the Australian cooking never sought an international recognition. But let us not be mistaken: Australia perfectly succeeded its metrication.

South Africa in 1973

Therefore a remarkable and deserving success. Which incidentally entails the excesses of beginners: in building construction and public works centimeters are never used, only millimeters, because the SI recommendation is to use suffixes from 1000 to 1000; on the contrary body size is always given in centimeters: giving it in meters and centimeters would too much look like feet and inches; car tire pressure is always in kilopascals; and to definitely depart from the Anglo-Saxon habits the decimal separator is comma, not point.

Canada is metric but too close to the United States...

Then things moved very quickly: government established the Metric Commission Canada, chaired by a just retired President of the Canadian Pacific Railway. Immediately the Commission set 1980 as target date for the metrication completion. More than hundred committees, each of them representing a constituent of the society, were set up to work out detailed plans of the metrication process. Resources were not limited: in 1972 at the Commission Chairman's initiative, walls were covered with posters featuring a nice lady in bikini suit with the caption "nobody can resist a girl with 91-61-91 mensurations"; most obviously the women lib organizations demanded that all posters be removed. Tooth paste was in 1974 the first consumer product labeled in metric. Degree Celsius replaced the degree Fahrenheit on 1st April 1975 - it was not a joke. From September 1975 on rain began to fall in millimeters and snow in centimeters. By 1st April 1976 - again not an April fool - all other meteorological data followed. Within the 1977 Labor Day week end all speed limit signs were changed on Canadian roads (through a system of decals: highway 1 is 7 700 km long!); remaining signs were changed in the following months. And in 1979 gasoline pumps were converted from gallons to liters.


Officially Canada is metric. In practice metrication went beyond the no-return point but stopped midway. To go to its term requires that the American elephant also achieves its metrication. It may take some time.





Treaty of Metre

United States