International Bureau of Weights and Measures

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International Bureau of Weights and Measures
Metric seal.svg
Convention du Metre.png
Metre Convention signatories
AbbreviationBIPM, IBWM
FormationMay 20, 1875;144 years ago (1875-05-20)
Type Intergovernmental
Region served
Official language
French and English
Martin Milton

Coordinates: 48°49′45.55″N2°13′12.64″E / 48.8293194°N 2.2201778°E / 48.8293194; 2.2201778 The International Bureau of Weights and Measures (French : Bureau international des poids et mesures) is an intergovernmental organization that was established by the Metre Convention, through which member states act together on matters related to measurement science and measurement standards (i.e. the International System of Units). The organisation is usually referred to by its French initialism, BIPM. The BIPM's secretariat and formal meetings are housed in the organizations headquarters in Sèvres, France.

Geographic coordinate system Coordinate system

A geographic coordinate system is a coordinate system that enables every location on Earth to be specified by a set of numbers, letters or symbols. The coordinates are often chosen such that one of the numbers represents a vertical position and two or three of the numbers represent a horizontal position; alternatively, a geographic position may be expressed in a combined three-dimensional Cartesian vector. A common choice of coordinates is latitude, longitude and elevation. To specify a location on a plane requires a map projection.

French language Romance language

French is a Romance language of the Indo-European family. It descended from the Vulgar Latin of the Roman Empire, as did all Romance languages. French evolved from Gallo-Romance, the spoken Latin in Gaul, and more specifically in Northern Gaul. Its closest relatives are the other langues d'oïl—languages historically spoken in northern France and in southern Belgium, which French (Francien) has largely supplanted. French was also influenced by native Celtic languages of Northern Roman Gaul like Gallia Belgica and by the (Germanic) Frankish language of the post-Roman Frankish invaders. Today, owing to France's past overseas expansion, there are numerous French-based creole languages, most notably Haitian Creole. A French-speaking person or nation may be referred to as Francophone in both English and French.

Metre Convention 1875 international treaty

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.


The BIPM is supervized by the International Committee for Weights and Measures (French : Comité international des poids et mesures, CIPM), a directorate of eighteen members that meet normally biannually, which is in turn overseen by the General Conference on Weights and Measures (French : Conférence générale des poids et mesures, CGPM) that meets in Paris usually once every four years, consisting of delegates of the governments of the Member States and observers from the Associates of the CGPM. These organs are also commonly referred to by their French initialisms.

The International Committee for Weights and Measures consists of eighteen persons, each of a different nationality, from Member States of the Metre Convention appointed by the General Conference on Weights and Measures (CGPM) whose principal task is to promote worldwide uniformity in units of measurement by taking direct action or by submitting proposals to the CGPM.

The General Conference on Weights and Measures (CGPM) is the supreme authority of the International Bureau of Weights and Measures, the inter-governmental organization established in 1875 under the terms of the Metre Convention through which Member States act together on matters related to measurement science and measurement standards. The CGPM is made up of delegates of the governments of the Member States and observers from the Associates of the CGPM. Under its authority, the International Committee for Weights and Measures – CIPM) executes an exclusive direction and supervision of the BIPM.


The BIPM was created on 20 May 1875, following the signing of the Metre Convention, a treaty among 59 Member States (as of November 2018). [1] It is based at the Pavillon de Breteuil in Sèvres, France, a 4.35 ha (10.7-acre) site (originally 2.52 ha (6.2 acres)) [2] granted to the Bureau by the French Government in 1876. Since 1969 the site of the Pavillon de Breteuil is considered international territory and the BIPM has all the rights and privileges accorded to an intergovernmental organization. [3] The status was further clarified by the French decree No 70-820 of 9 September 1970. [2]

Treaty Express agreement under international law entered into by actors in international law

A treaty is a formal written agreement entered into by actors in international law, namely sovereign states and international organizations. A treaty may also be known as an international agreement, protocol, covenant, convention, pact, or exchange of letters, among other terms. Regardless of terminology, all these instruments may be considered treaties subject to the same rules under international law.

Pavillon de Breteuil

Pavillon de Breteuil is a building located in Saint-Cloud, France near Paris. It was inaugurated by Louis XIV in 1672. It is in the park of the former royal Château de Saint-Cloud, which was destroyed in 1870.

Sèvres Commune in Île-de-France, France

Sèvres is a commune in the southwestern suburbs of Paris, France. It is located 9.9 kilometres from the centre of Paris and is in the department of Hauts-de-Seine in the region of Île-de-France.


The BIPM has the mandate to provide the basis for a single, coherent system of measurements throughout the world, traceable to the International System of Units (SI). This task takes many forms, from direct dissemination of units to coordination through international comparisons of national measurement standards (as in electricity and ionizing radiation).

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 second, metre, kilogram, ampere, kelvin, mole, candela, 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.

Following consultation, a draft version of the BIPM Work Programme is presented at each meeting of the General Conference for consideration with the BIPM dotation. The final programme of work is determined by the CIPM in accordance with the dotation agreed by the CGPM.

Currently, main work of the BIPM include: [4]

The BIPM has an important role in maintaining accurate worldwide time of day. It combines, analyses, and averages the official atomic time standards of member nations around the world to create a single, official Coordinated Universal Time (UTC). [5]

Coordinated Universal Time Primary time standard by which the world regulates clocks and time

Coordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is within about 1 second of mean solar time at 0° longitude, and is not adjusted for daylight saving time. In some countries where English is spoken, the term Greenwich Mean Time (GMT) is often used as a synonym for UTC and predates UTC by nearly 300 years.


Pavillon de Breteuil in Saint-Cloud, France BIPM courtyard.jpg
Pavillon de Breteuil in Saint-Cloud, France

Since its establishment, the directors of the BIPM have been: [6] [7]

Gilbert Govi Italy 1875–1877
J. Pernet Switzerland 1877–1879Acting director
Ole Jacob Broch Norway 1879–1889
J.-René Benoît France 1889–1915
Charles Édouard Guillaume Switzerland 1915–1936
Albert Pérard France 1936–1951
Charles VoletSwitzerland1951–1961
Jean TerrienFrance1962–1977
Pierre GiacomoFrance1978–1988
Terry J. Quinn United Kingdom 1988–2003Honorary director
Andrew J. WallardUnited Kingdom2004–2010Honorary director
Michael Kühne Germany 2011–2012
Martin J. T. MiltonUnited Kingdom2013–present

Metrological international projects

Flow Measurement

The BIPM centralises diverse international projects involving public & independent institutes of metrology.

For example:

See also


The BIPM YouTube channel

Related Research Articles

Kilogram SI unit of mass

The kilogram is the base unit of mass in the metric system, formally the International System of Units (SI), having the unit symbol kg. It is a widely used measure in science, engineering, and commerce worldwide, and is often called a kilo. The kilogram is almost exactly the mass of one litre of water.

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.

SI base unit One of the seven units of measurement that define the Metric System

The SI base units are seven units of measure defined by the International System of Units as the basic set from which all other SI units can be derived. The units and their physical quantities are the second for time, the metre for measurement of length, the kilogram for mass, the ampere for electric current, the kelvin for temperature, the mole for amount of substance, and the candela for luminous intensity.

Metrology Science of measurement and its application

Metrology is the science of measurement. It establishes a common understanding of units, crucial in linking human activities. Modern metrology has its roots in the French Revolution's political motivation to standardise units in France, when a length standard taken from a natural source was proposed. This led to the creation of the decimal-based metric system in 1795, establishing a set of standards for other types of measurements. Several other countries adopted the metric system between 1795 and 1875; to ensure conformity between the countries, the Bureau International des Poids et Mesures (BIPM) was established by the Metre Convention. This has evolved into the International System of Units (SI) as a result of a resolution at the 11th Conference Generale des Poids et Mesures (CGPM) in 1960.

Articles related to standards include:

The standard acceleration due to gravity, sometimes abbreviated as standard gravity, usually denoted by ɡ0 or ɡn, is the nominal gravitational acceleration of an object in a vacuum near the surface of the Earth. It is defined by standard as 9.80665 m/s2. This value was established by the 3rd CGPM and used to define the standard weight of an object as the product of its mass and this nominal acceleration. The acceleration of a body near the surface of the Earth is due to the combined effects of gravity and centrifugal acceleration from the rotation of the Earth ; the total is about 0.5% greater at the poles than at the Equator.

Units of measurement in 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.

Metrologia is an international journal dealing with the scientific aspects of metrology. It has been running since 1965 and has been published by the Bureau International des Poids et Mesures (BIPM) since 1991. Since 2003 the journal has been published by IOP Publishing on behalf of the BIPM. Metrologia covers the fundamentals of measurements, in particular those dealing with the 7 base units of the International System of Units or proposals to replace them.

The kelvin is the base unit of temperature in the International System of Units (SI), having the unit symbol K. It is named after the Belfast-born, Glasgow University engineer and physicist William Thomson, 1st Baron Kelvin (1824–1907).

Parc de Saint-Cloud park is located on the site of the Château de Saint-Cloud

The Parc de Saint-Cloud, officially the Domaine National de Saint-Cloud, is a domaine national, located mostly within Saint-Cloud, in the Hauts-de-Seine department, near Paris, France.

Standard (metrology) embodiment of a unit of measurement

In metrology, a standard is an object, system, or experiment that bears a defined relationship to a unit of measurement of a physical quantity. Standards are the fundamental reference for a system of weights and measures, against which all other measuring devices are compared. Historical standards for length, volume, and mass were defined by many different authorities, which resulted in confusion and inaccuracy of measurements. Modern measurements are defined in relationship to internationally standardized reference objects, which are used under carefully controlled laboratory conditions to define the units of length, mass, electrical potential, and other physical quantities.

2019 redefinition of the SI base units Redefinition of the SI base units kilogram, ampere, kelvin, and mole

In 2019, the SI base units were redefined, effective on 144th anniversary of the Metre Convention, 20 May 2019. In the redefinition, four of the seven SI base units – the kilogram, ampere, kelvin, and mole – were redefined by setting exact numerical values for the Planck constant, the elementary electric charge, the Boltzmann constant, and the Avogadro constant, respectively. The second, metre, and candela were already defined by physical constants and were subject to correction to their definitions. The new definitions aimed to improve the SI without changing the value of any units, ensuring continuity with existing measurements. In November 2018, the 26th General Conference on Weights and Measures (CGPM) unanimously approved these changes, which the International Committee for Weights and Measures (CIPM) had proposed earlier that year after determining that previously agreed conditions for the change had been met. These conditions were satisfied by a series of experiments that measured the constants to high accuracy relative to the old SI definitions, and were the culmination of decades of research.

The history of the metric system began in the Age of Enlightenment with notions of length and weight taken from natural ones, and decimal multiples and fractions of them. The system 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.

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.


  1. "Brief history of the SI". BIPM. Retrieved 21 April 2009.
  2. 1 2 Page, Chester H; Vigoureux, Paul, eds. (20 May 1975). The International Bureau of Weights and Measures 1875–1975: NBS Special Publication 420. Washington, D.C.: National Bureau of Standards. pp. 26–27.
  3. "History of the Pavillon de Breteuil". BIPM. Retrieved 9 November 2018.
  4. "BIPM: Our work programme". BIPM. Retrieved 9 November 2018.
  5. "BIPM Time Coordinated Universal Time (UTC)". BIPM. Retrieved 29 December 2013.
  6. "Directors of the BIPM since 1875". Bureau International des Poids et Mesures. 2018. Retrieved 9 November 2018.
  7. "NPL Fellow, Dr Martin Milton, is new Director at foundation of world's measurement system". QMT News. Quality Manufacturing Today. August 2012. Retrieved 30 September 2012.