Units of measurement in France

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Woodcut dated 1800 illustrating the new decimal units which became the legal norm across all France on 4 November 1800 Poids et mesures.png
Woodcut dated 1800 illustrating the new decimal units which became the legal norm across all France on 4 November 1800
Table of the measuring units used in the 17th century at Pernes-les-Fontaines in the covered market at Provence-Alpes-Cote d'Azur region of southeastern France Pernes - Mesures anciennes.JPG
Table of the measuring units used in the 17th century at Pernes-les-Fontaines in the covered market at Provence-Alpes-Côte d'Azur region of southeastern France

France has a unique history of units of measurement due to the radical decision to invent and adopt the metric system after the French Revolution. The metric system following the French Revolution.

France Republic with mainland in Europe and numerous oversea territories

France, officially the French Republic, is a country whose territory consists of metropolitan France in Western Europe and several overseas regions and territories. The metropolitan area of France extends from the Mediterranean Sea to the English Channel and the North Sea, and from the Rhine to the Atlantic Ocean. It is bordered by Belgium, Luxembourg and Germany to the northeast, Switzerland and Italy to the east, and Andorra and Spain to the south. The overseas territories include French Guiana in South America and several islands in the Atlantic, Pacific and Indian oceans. The country's 18 integral regions span a combined area of 643,801 square kilometres (248,573 sq mi) and a total population of 67.3 million. France, a sovereign state, is a unitary semi-presidential republic with its capital in Paris, the country's largest city and main cultural and commercial centre. Other major urban areas include Lyon, Marseille, Toulouse, Bordeaux, Lille and Nice.

Metric system decimal system of units of measurement

The metric system is an internationally recognised decimalised system of measurement. It is in widespread use, and where it is adopted, it is the only or most common system of weights and measures. It is now known as the International System of Units (SI). It is used to measure everyday things such as the mass of a sack of flour, the height of a person, the speed of a car, and the volume of fuel in its tank. It is also used in science, industry and trade.

French Revolution social and political revolution in France and its colonies occurring from 1789 to 1798

The French Revolution was a period of far-reaching social and political upheaval in France and its colonies beginning in 1789. The Revolution overthrew the monarchy, established a republic, catalyzed violent periods of political turmoil, and finally culminated in a dictatorship under Napoleon who brought many of its principles to areas he conquered in Western Europe and beyond. Inspired by liberal and radical ideas, the Revolution profoundly altered the course of modern history, triggering the global decline of absolute monarchies while replacing them with republics and liberal democracies. Through the Revolutionary Wars, it unleashed a wave of global conflicts that extended from the Caribbean to the Middle East. Historians widely regard the Revolution as one of the most important events in human history.


In the Ancien régime, before 1795, France used a system of measures that had many of the characteristics of the modern Imperial System of units. There was widespread abuse of the king's standards to the extent that the lieue could vary from 3.268 km in Beauce to 5.849 km in Provence. In the revolutionary era, France used the first version of the metric system. This system was not well received by the public. Between 1812 and 1837, the mesures usuelles was used – traditional names were restored, but were based on metric units: for example, the livre became 500 g. After 1837, the metric system was reintroduced and has remained the principal system of use to this day.

Beauce, France French natural region

Beauce is a natural region in northern France, located between the Seine and Loire rivers. It now comprises the Eure-et-Loir département and parts of Loiret, Essonne and Loir-et-Cher.

Provence Historical province in Provence-Alpes-Côte dAzur, France

Provence is a geographical region and historical province of southeastern France, which extends from the left bank of the lower Rhône River to the west to the Italian border to the east, and is bordered by the Mediterranean Sea to the south. It largely corresponds with the modern administrative région of Provence-Alpes-Côte d'Azur, and includes the départements of Var, Bouches-du-Rhône, Alpes-de-Haute-Provence and parts of Alpes-Maritimes and Vaucluse. The largest city of the region is Marseille.

Mesures usuelles were a system of measurement introduced by Napoleon I in 1812 to act as compromise between the metric system and traditional measurements. The system was restricted to use in the retail industry and continued in use until 1839.

Ancien régime (to 1795)

In the pre-revolutionary era (before 1795), France used a system of measures that had many of the characteristics of the modern Imperial System of units, but there was no unified system of measurement. Charlemagne and successive kings had tried but failed to impose a unified system of measurement in France. [1] (In England, by contrast, the Magna Carta decreed that "there shall be one unit of measure throughout the realm.")

Magna Carta Angevin charter

Magna Carta Libertatum, commonly called Magna Carta, is a charter of rights agreed to by King John of England at Runnymede, near Windsor, on 15 June 1215. First drafted by the Archbishop of Canterbury to make peace between the unpopular King and a group of rebel barons, it promised the protection of church rights, protection for the barons from illegal imprisonment, access to swift justice, and limitations on feudal payments to the Crown, to be implemented through a council of 25 barons. Neither side stood behind their commitments, and the charter was annulled by Pope Innocent III, leading to the First Barons' War. After John's death, the regency government of his young son, Henry III, reissued the document in 1216, stripped of some of its more radical content, in an unsuccessful bid to build political support for their cause. At the end of the war in 1217, it formed part of the peace treaty agreed at Lambeth, where the document acquired the name Magna Carta, to distinguish it from the smaller Charter of the Forest which was issued at the same time. Short of funds, Henry reissued the charter again in 1225 in exchange for a grant of new taxes. His son, Edward I, repeated the exercise in 1297, this time confirming it as part of England's statute law.

The names and relationships of many units of measure were adopted from Roman units of measure and many more were added – it has been estimated that there were seven or eight hundred different names for the various units of measure. In addition, the quantity associated with each unit of measure differed from town to town and even from trade to trade to such an extent that the lieue (league) could vary from 3.268 km in Beauce to 5.849 km in Provence. It has been estimated that, on the eve of the Revolution, a quarter of a million different units of measure were in use in France. [2] Although certain standards, such as the pied du roi (the king's foot) had a degree of pre-eminence and were used by savants across Europe, many traders chose to use their own measuring devices, giving scope for fraud and hindering commerce and industry. [1]

As an example, the weights and measures used at Pernes-les-Fontaines in southeastern France differ from those catalogued later in this article as having been used in Paris. In many cases, the names are different, while the livre is shown as being 403 g, as opposed to 489 g – the value of the livre du roi. (The Imperial pound is about 453.6 g.)

Pernes-les-Fontaines Commune in Provence-Alpes-Côte dAzur, France

Pernes-les-Fontaines is a commune in the Vaucluse department in the Provence-Alpes-Côte d'Azur region in southeastern France.

Revolutionary France (1795–1812)

A clock of the republican era showing both decimal and standard time. Horloge-republicaine4.jpg
A clock of the republican era showing both decimal and standard time.

The French Revolution and subsequent Napoleonic Wars marked the end of the Age of Enlightenment. The forces of change that had been brewing manifest themselves across all of France, including the way in which units of measure should be defined. The savants of the day favoured the use of a system of units that were inter-related and which used a decimal basis.

Napoleonic Wars Series of early 19th century European wars

The Napoleonic Wars (1803–1815) were a series of major conflicts pitting the French Empire and its allies, led by Napoleon I, against a fluctuating array of European powers formed into various coalitions, financed and usually led by the United Kingdom. The wars stemmed from the unresolved disputes associated with the French Revolution and its resultant conflict. The wars are often categorised into five conflicts, each termed after the coalition that fought Napoleon: the Third Coalition (1805), the Fourth (1806–07), the Fifth (1809), the Sixth (1813), and the Seventh (1815).

Age of Enlightenment European cultural movement of the 18th century

The Age of Enlightenment was an intellectual and philosophical movement that dominated the world of ideas in Europe during the 18th century, the "Century of Philosophy".

There was also a wish that the units of measure should be for all people and for all time and therefore not dependent on an artefact owned by any one particular nation. Talleyrand, at the prompting of the savant Condorcet, approached the British and the Americans in the early 1790s with proposals of a joint effort to define the metre. In the end, these approaches came to nothing and France decided to "go it alone". [3]

Decimal time was introduced in the decree of 5 October 1793 under which the day was divided into 10 "decimal hours", the "hour" into 100 " decimal minutes" and the "decimal minute" into 100 "decimal seconds". The "decimal hour" corresponded to 2 hr 24 min, the "decimal minute" to 1.44 min and the "decimal second" to 0.864 s.

The implementation of decimal time proved an immense task and under the article 22 of the law of 18 Germinal, Year III (7 April 1795), the use of decimal time was no longer mandatory. [4] On 1 January 1806, France reverted to the traditional timekeeping. [5]

The Paris meridian, which passes through the Observatoire de Paris. The metre was defined along this meridian using a survey that stretched from Dunkirk to Barcelona. Obs-Paris-meridienne.jpg
The Paris meridian, which passes through the Observatoire de Paris. The metre was defined along this meridian using a survey that stretched from Dunkirk to Barcelona.

The metric system of measure was first given a legal basis in 1795 by the French Revolutionary government. Article 5 of the law of 18 Germinal, Year III (7 April 1795) defined five units of measure. The units and their preliminary values were: [6]

Decimal multiples and submultiples of these units would be defined by Greek prefixes - "myria", "kilo", "hecta" (100), "deka" - and Latin prefixes - "deci", "centi" and "milli". Using Cassini's survey of 1744, a provisional value of 443.44 lignes was assigned to the metre which, in turn, defined the other units of measure. [7]

The final value of the metre had to wait until 1799, when Delambre and Mechain presented the results of their survey between Dunkirk and Barcelona that fixed the length of the metre at 443.296 lignes. The law 19 Frimaire An VIII (10 December 1799) defined the metre in terms of this value and the kilogram as being 18,827.15 grains. These definitions enabled the construction of reference copies of the kilogram and metre, which were to be used as standards for the next 90 years.

At the same time, a new decimal-based system for angular measurement was implemented. The right angle was divided into 100 grads, which in turn was divided in 100 centigrads. An arc on the earth’s surface formed by an angle of one centigrad was one kilometre.

Mesures usuelles (1812–1839)

The Mesures usuelles were introduced by Napoleon I in 1812 Napoleon Groot.jpg
The Mesures usuelles were introduced by Napoleon I in 1812

The metric system was introduced into France in 1795 on a district by district basis, starting with Paris. However, by modern standards, the introduction was poorly managed. Although thousands of pamphlets were distributed, the Agency of Weights and Measures, which oversaw the introduction, underestimated the work involved. Paris alone needed 500,000 metre sticks, yet one month after the metre became the sole legal unit of measure, there were only 25,000 in store. [8] This, combined with other excesses of the Revolution made the metric system unpopular.

Napoleon ridiculed the metric system, but as an able administrator, he recognised the value of a sound basis for a system of measurement. Under the décret impérial du 12 février 1812 (imperial decree of 12 February 1812), he introduced a revised system of measure – the mesures uselles or "customary measures" for use in small retail businesses. However, all government, legal and similar works still had to use the metric system and the metric system continued to be taught at all levels of education. [9] The names of many pre-metric units were reintroduced, but were redefined in terms of metric units. Thus the toise (fathom) was defined as being two metres with six pied (feet) making up one toise, twelve pouce (inches) making up one pied and twelve lignes making up one pouce. Likewise, the livre (pound) was defined as being 500 g, each livre comprising sixteen once and each once eight gros and the aune as 120 centimetres. [10]

The metric system restored (1840–1875)

La loi du 4 juillet 1837 (the law of 4 July 1837) effectively revoked the use of mesures usuelles by reaffirming the laws of measurement of 1795 and 1799 to be used from 1 May 1840. [1] However, many units of measure, such as the livre, remained in colloquial use for many years and the livre still does to some extent.

When this legislation was introduced, the metric system was beginning to take hold across Europe. Switzerland and the German state of Baden had both defined their Fuß (foot) as being 300 mm and the German state of Hessen-Darmstadt has defined its Fuß as being 250 mm. Moreover, the Netherlands, Belgium, Greece, Lombardy and Venice had all adopted the metric system, albeit with local names for the "metre", "kilogram" and so on. [11] The metric system was given a boost when the German Zollverein (Customs Union) introduced the Zollpfund of 500 g in 1850.

The Great Exhibition of 1851 in London was followed by international exhibitions in Paris in 1855 and 1867. The 1867 exhibition had a stand showing how the diverse units of measure were converging onto the metric system – a system that had been developed in France and whose standards were in the custody of the French government, but available for world use. [12]

In 1870, while France was preparing to host an international conference to discuss international cooperation in the sphere of units of measurement, the war broke out. France was humiliated by Prussia's military action, but in 1872 France seized the diplomatic initiative and re-issued the invitations for the 1870 conference. The conference met in 1875 and concluded with the signing of the Treaty of the Metre. The principal agreements under the treaty were: [13]

Thus the French metre and kilogram passed into international control.

International era (1875 onwards)

During the early part of the twentieth century, the French introduced their own units of power - the poncelet , which was defined as being the power required to raise a mass of 100 kg against standard gravity with a velocity of 1 m/s giving a value of 980.665 W. [15] [16] However, many other European countries defined their units of power (the Pferdestärke in Germany, the paardekracht in the Netherlands and the cavallo vapore in Italy) using 75 kg rather than 100 kg, which gave a value of 735.49875 W (about 0.985  HP). Eventually, the poncelet was replaced with the cheval vapeur, which was identical to equivalent units of measure in neighbouring countries. In 1977, these units, along with the stere and the livre (and amongst others, the German pfund) were proscribed by EEC Directive 71/354/EEC [17] which required EU member states to standardise on the International System of Units (SI) and therefore to use the watt and its multiples.

See also

Related Research Articles

Kilogram SI unit of mass

The kilogram or kilogramme is the base unit of mass in the International System of Units (SI). Until 20 May 2019, it remains defined by a platinum alloy cylinder, the International Prototype Kilogram, manufactured in 1889, and carefully stored in Saint-Cloud, a suburb of Paris. After 20 May, it will be defined in terms of fundamental physical constants.

Litre non-SI unit of volume

The litre or liter is an SI accepted metric system unit of volume equal to 1 cubic decimetre (dm3), 1,000 cubic centimetres (cm3) or 1/1,000 cubic metre. A cubic decimetre occupies a volume of 10 cm×10 cm×10 cm and is thus equal to one-thousandth of a cubic metre.

The metre or meter is the base unit of length in the International System of Units (SI). The SI unit symbol is m. The metre is defined as the length of the path travelled by light in vacuum in 1/299 792 458 of a second.


Metrication or metrification is conversion to the metric system of units of measurement. Worldwide, there has been a long process of independent conversions of countries from various local and traditional systems, beginning in France during the 1790s and spreading widely over the following two centuries, but the metric system has not been fully adopted in all countries and sectors.

Metre Convention

The Metre Convention, also known as the Treaty of the Metre, is an international treaty that was signed in Paris on 20 May 1875 by representatives of 17 nations. The treaty created the International Bureau of Weights and Measures (BIPM), an intergovernmental organization under the authority of the General Conference on Weights and Measures (CGPM) and the supervision of the International Committee for Weights and Measures (CIPM), that coordinates international metrology and the development of the metric system.

International System of Units a system of units of measurement for base and derived physical quantities

The International System of Units is the modern form of the metric system, and is the most widely used system of measurement. It comprises a coherent system of units of measurement built on seven base units, which are the ampere, kelvin, second, metre, kilogram, candela, mole, and a set of twenty prefixes to the unit names and unit symbols that may be used when specifying multiples and fractions of the units. The system also specifies names for 22 derived units, such as lumen and watt, for other common physical quantities.

Gram Unit of mass 1/1000th of a kilogram

The gram is a metric system unit of mass.


Myria- (symbol my) is a now obsolete decimal metric prefix denoting a factor of 104 (ten thousand). It originates from the Greek μύριοι (mýrioi) (myriad). The prefix was part of the original metric system adopted by France in 1795, but was not adopted when the SI prefixes were internationally adopted by the 11th CGPM conference in 1960.

The "Plan for Establishing Uniformity in the Coinage, Weights, and Measures of the United States" was a report submitted to the U.S. House of Representatives on July 13, 1790, by Secretary of State Thomas Jefferson.

A system of measurement is a collection of units of measurement and rules relating them to each other. Systems of measurement have historically been important, regulated and defined for the purposes of science and commerce. Systems of measurement in use include the International System of Units (SI), the modern form of the metric system, the imperial system, and United States customary units.

The spread of metrication around the world in the last two centuries has been met with both support and opposition. All countries except Burma (Myanmar), Liberia, and the United States of America have officially adopted the metric system, although Liberia has seen some introduction of metric units, and in 2013 Burma formally announced the beginning of its metrication program. The metric system has been largely adopted in the United Kingdom, Canada and Ireland, without having fully displaced the imperial units from all areas of life. In other Anglophone countries such as Australia, Singapore and New Zealand, imperial units have been formally deprecated and are no longer officially sanctioned for use.

Grave (unit) predecessor to the kilogram

The grave was the original name of the kilogram, in an early version of the metric system between 1793 and 1795.

Hectare metric unit of area

The hectare is an SI accepted metric system unit of area equal to a square with 100-metre sides, or 10,000 m2, and is primarily used in the measurement of land. There are 100 hectares in one square kilometre. An acre is about 0.405 hectare and one hectare contains about 2.47 acres.

French units could refer to any of:

Units of measurement in France before the French Revolution

Before the French Revolution, which started in 1789, French units of measurement were based on the Carolingian system, introduced by the first Holy Roman Emperor Charlemagne (800 – 814 AD) which in turn were based on ancient Roman measures. Charlemagne brought a consistent system of measures across the entire empire. However, after his death, the empire fragmented and many rulers introduced their own variants of the units of measure.

The history of the metric system began in the Age of Enlightenment with simple notions of length and weight taken from natural ones, and decimal multiples and fractions of them. The system was so useful it became the standard of France and Europe in half a century. Other dimensions with unity ratios were added, and it went on to be adopted by the world.

Introduction to the metric system

The metric system was developed during the French Revolution to replace the various measures previously used in France. The metre is the unit of length in the metric system and was originally based on the dimensions of the earth, as far as it could be measured at the time. The litre, is the unit of volume and was defined as one thousandth of a cubic metre. The metric unit of mass is the kilogram and it was defined as the mass of one litre of water. The metric system was, in the words of French philosopher Marquis de Condorcet, "for all people for all time".

Outline of the metric system Overview of and topical guide to the metric system

The following outline is provided as an overview of and topical guide to the metric system – various loosely related systems of measurement that trace their origin to the decimal system of measurement introduced in France during the French Revolution.


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  2. Adler, Ken (2002). The Measure of All Things: The Seven-Year Odyssey That Transformed the World. Nepal: Jay Prajapatri. pp. 2–3. ISBN   0349115079.
  3. Adler. pp. 88–96.Missing or empty |title= (help)
  4. "Décret relatif aux poids et aux mesures. 18 germinal an 3 (7 avril 1795)". Le systeme metrique decimal (in French). Retrieved 2011-02-07.
  5. "Dials & Symbols of the French revolution. The Republican Calendar and Decimal time". The Horological Foundation. Retrieved 2011-02-07.
  6. "La loi du 18 Germinal an 3 (The law of 18 Germanial year 3) " la mesure [républicaine] de superficie pour les terrains, égale à un carré de dix mètres de côté "". Le CIV (Centre d'Instruction de Vilgénis) – Forum des Anciens. Retrieved 2010-03-02.
  7. Adler. p. 106.Missing or empty |title= (help)
  8. Adler. p. 269.Missing or empty |title= (help)
  9. Denis Février. "Un historique du mètre" (in French). Ministère de l'Economie, des Finances et de l'Industrie. Retrieved 2011-03-10.
  10. Hallock, William; Wade, Herbert T (1906). "Outlines of the evolution of weights and measures and the metric system". London: The Macmillan Company. pp. 66–69.
  11. Adler. pp. 349–357.Missing or empty |title= (help)
  12. Wolfgang Appell (2002). "Amtliche Maßeinheiten in Europa 1842" [Official units of measure in Europe 1842] (in German). ISBN   3-7686-1036-5 . Retrieved 2011-02-10Website based on Alte Meß und Währungssysteme aus dem deutschen Sprachgebiet
  13. "The Metre Convention". Bureau international des poids et mesures/International Bureau of Weights and Measures (BIPM). Retrieved 2011-02-13.
  14. FJ Smith (1973). "Standard Kilogram Weights: A Story of Precision Fabrication" (PDF). Platinum Metals Review. Johnson Matthey. 17 (2): 66–68. Retrieved 2011-03-07.
  15. "poncelet (physics)". The Free Dictionary by Farlex. Retrieved 2011-02-17.
  16. Thiery Thomasset, Universitié de Technology, Compiègne (December 2010). "Jean Victor Poncelet (1788-1867)" (PDF). Tout sur les unités de mesure (in French). Retrieved 2011-02-17.
  17. "Council Directive of 18 October 1971 on the approximation of laws of the member states relating to units of measurement, (71/354/EEC)" . Retrieved 2009-02-07.