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(, ''customary measures'') were a French system of measurement introduced by French Emperor
Napoleon I Napoleon Bonaparte (born Napoleone di Buonaparte; 15 August 1769 – 5 May 1821), later known by his regnal name Napoleon I, was a French general and statesman who rose to prominence during the French Revolution and led Military career ...
in 1812 to act as compromise between the
metric system The metric system is a system of measurement that standardization, standardizes a set of base units and a nomenclature for describing relatively large and small quantities via decimal-based multiplicative unit prefixes. Though the rules gover ...
and traditional measurements. The system was restricted to use in the retail industry and continued in use until 1840, when the laws of measurement from 1795 and 1799 were reinstituted.


Rationale behind the new system

In the five years immediately before the
French First Republic In the history of France, the First Republic (), sometimes referred to in historiography as Revolutionary France, and officially the French Republic (), was founded on 21 September 1792 during the French Revolution. The First Republic lasted un ...
introduced the
metric system The metric system is a system of measurement that standardization, standardizes a set of base units and a nomenclature for describing relatively large and small quantities via decimal-based multiplicative unit prefixes. Though the rules gover ...
, every effort was made to make the citizens aware of the upcoming changes and to prepare them for it. The administration distributed tens of thousands of educational pamphlets, private enterprise produced educational games, guides,
almanacs An almanac (also spelled almanack and almanach) is a regularly published listing of a set of current information about one or multiple subjects. It includes information like weather forecasting, weather forecasts, farmers' sowing, planting dates ...
, and conversion aids, and metre standards were built into the walls of prominent buildings around
Paris Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, largest city of France. With an estimated population of 2,048,472 residents in January 2025 in an area of more than , Paris is the List of ci ...
. The introduction was phased by district over the next few years, with Paris being the first district to change. The government also realised that the people would need metre rulers, but they had only provided 25,000 of the 500,000 rulers needed in Paris as late as one month after the metre became the sole legal unit of measure. To compensate, the government introduced incentives for the mass-production of rulers. Paris police reported widespread flouting of the requirement for merchants to use only the metric system. Where the new system was in use, it was abused, with shopkeepers taking the opportunity to round prices up and to give smaller measures. Napoleon I, the French Emperor, disliked the inconvenience of surrendering the high factorability of traditional measures in the name of
decimal The decimal numeral system (also called the base-ten positional numeral system and denary or decanary) is the standard system for denoting integer and non-integer numbers. It is the extension to non-integer numbers (''decimal fractions'') of th ...
isation, and recognised the difficulty of getting it accepted by the populace. Under the (imperial decree of 12 February 1812), he introduced a new system of measurement, the 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. The
prototype A prototype is an early sample, model, or release of a product built to test a concept or process. It is a term used in a variety of contexts, including semantics, design, electronics, and Software prototyping, software programming. A prototype ...
s of the metric unit, the
kilogram The kilogram (also spelled kilogramme) is the base unit of mass in the International System of Units (SI), equal to one thousand grams. It has the unit symbol kg. The word "kilogram" is formed from the combination of the metric prefix kilo- (m ...
and the
metre The metre (or meter in US spelling; symbol: m) is the base unit of length in the International System of Units (SI). Since 2019, the metre has been defined as the length of the path travelled by light in vacuum during a time interval of of ...
, enabled an immediate standardisation of measurement over the whole country, replacing the varying legal measures in different parts of the country, and even more across the whole of
Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...
. The new (known as the ) was defined as five hundred
gram The gram (originally gramme; SI unit symbol g) is a Physical unit, unit of mass in the International System of Units (SI) equal to one thousandth of a kilogram. Originally defined in 1795 as "the absolute Mass versus weight, weight of a volume ...
s, and the new () was defined as two metres. Products could be sold in shops under the old names and with the old relationships to one another, but with metric-based and slightly changed absolute sizes. This series of measurements was called . Napoleon's decree was eventually revoked during the reign of King
Louis Philippe I Louis Philippe I (6 October 1773 – 26 August 1850), nicknamed the Citizen King, was King of the French from 1830 to 1848, the penultimate monarch of France, and the last French monarch to bear the title "King". He abdicated from his throne ...
by the (law of 4 July 1837), which took effect on 1 January 1840, and reinstated the original metric system. This brought the system of to a legal end, though the remains in some informal use to this day.


Permitted units

The law authorised the following units of measure: * The (fathom) was defined as exactly two metres and was as before divided into 6 (or "feet") or 72 (inches). The was divided into 12 (or "lines"). The and , at precisely 333. mm and 27. mm, were about 2.6% larger than the previous Parisian measures and 9% larger than their English counterparts. * The ( ell), used to measure cloth, was defined as 120 centimetres, and divided into the (half an ell, or 60 cm) and the (third of an ell, or 40 cm). It was 1.3% larger than (118.48 cm) and 5.0% larger than its English counterpart (45 inches; 114.3 cm). * The
litre The litre ( Commonwealth spelling) or liter ( American spelling) (SI symbols L and l, other symbol used: ℓ) is a metric unit of volume. It is equal to 1 cubic decimetre (dm3), 1000 cubic centimetres (cm3) or 0.001 cubic metres (m3). A ...
was subdivided like a British
quart The quart (symbol: qt) is a unit of volume equal to a quarter of a gallon. Three kinds of quarts are currently used: the liquid quart and dry quart of the US customary system and the of the British imperial system. All are roughly equal ...
, into (literally, "halves", being the equivalent of a
pint The pint (, ; symbol pt, sometimes abbreviated as ''p'') is a unit of volume or capacity in both the imperial and United States customary measurement systems. In both of those systems, it is one-eighth of a gallon. The British imperial pint ...
of about sixteen
fluid ounce A fluid ounce (abbreviated fl oz, fl. oz. or oz. fl., old forms ℥, fl ℥, f℥, ƒ ℥) is a unit of volume (also called ''capacity'') typically used for measuring liquids. The British Imperial, the United States customary, and the United S ...
s), (literally, "fourths", being the equivalent of a cup of about eight fluid ounces), (literally, "eighths"), and (literally, "sixteenths", of about two fluid ounces). * The , (
bushel A bushel (abbreviation: bsh. or bu.) is an Imperial unit, imperial and United States customary units, US customary unit of volume, based upon an earlier measure of dry capacity. The old bushel was used mostly for agriculture, agricultural pr ...
), was redefined as being an eighth of a hectolitre and with associated measures , and (double, half, and quarter bushels respectively). The original , like the English bushel, varied depending on the it was used, as well as the it was used. * The , ( pound), was defined as 500 grams, divided into 16 , (ounces), each being divided into 8 . Each gros being thought of as being composed of 72 , whose name is the same as in English. Hence, the livre was 9216 . The and were about 10% larger than their English counterparts, while the was 17% less than its English counterpart. The did not include any units of length greater than the - the (10 km) remaining in use throughout this period.. (Website based on , .)


See also

* French units of measurement *
History of measurement The earliest recorded systems of weights and measures originate in the 3rd or 4th millennium BC. Even the very earliest civilizations needed measurement for purposes of agriculture, construction and trade. Early standard units might only have ap ...
* History of the metric system *
International System of Units The International System of Units, internationally known by the abbreviation SI (from French ), is the modern form of the metric system and the world's most widely used system of measurement. It is the only system of measurement with official s ...
*
List of unusual units of measurement An unusual unit of measurement is a unit of measurement that does not form part of a coherent system of measurement, especially because its exact quantity may not be well known or because it may be an inconvenient multiple or fraction of a base ...
*
Metric system The metric system is a system of measurement that standardization, standardizes a set of base units and a nomenclature for describing relatively large and small quantities via decimal-based multiplicative unit prefixes. Though the rules gover ...
*
Systems of measurement A system of units of measurement, also known as a system of units or 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 defi ...
*
Units of measurement A unit of measurement, or unit of measure, is a definite magnitude (mathematics), magnitude of a quantity, defined and adopted by convention or by law, that is used as a standard for measurement of the same kind of quantity. Any other qua ...


References

{{Napoleon 1812 introductions Systems of units Science and technology in France Metrication in France Obsolete units of measurement Napoleon