The General Conference on Weights and Measures (abbreviated CGPM from the ) is the supreme authority of the International Bureau of Weights and Measures (BIPM), the intergovernmental 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. It elects the International Committee for Weights and Measures (abbreviated CIPM from the ) as the supervisory board of the BIPM to direct and supervise it.

Initially the work of the BIPM concerned the kilogram and the metre, but in 1921 the scope of the Metre Convention was extended to accommodate all physical measurements and hence all aspects of the metric system. In 1960 the 11th CGPM approved the title International System of Units, usually known as "SI".

The General Conference receives the report of the CIPM on work accomplished; it discusses and examines the arrangements required to ensure the propagation and improvement of the International System of Units (SI); it endorses the results of new fundamental metrological determinations and various scientific resolutions of international scope; and it decides all major issues concerning the organization and development of the BIPM, including its financial endowment.

The CGPM meets in Paris, usually once every four years. The 25th meeting of the CGPM took place from 18 to 20 November 2014, the 26th meeting of the CGPM took place in Versailles from 13 to 16 November 2018, and the 27th meeting of the CGPM took place from 15 to 18 November 2022. The 28th meeting of the CGPM will take place from 13 to 15 October 2026.

Establishment On 20 May 1875 an international treaty known as the Convention du Mètre (Metre Convention) 1875 text plus 1907 and 1921 amendments. was signed by 17 states. This treaty established an international organization, the Bureau international des poids et mesures (BIPM), which has two governing organs: Conférence générale des poids et mesures (CGPM), a plenary meeting of official delegates of member states which is the supreme authority for all actions; Comité international des poids et mesures (CIPM), consisting of elected scientists and metrologists, which prepares and executes the decisions of the CGPM and is responsible for the supervision of the organization.

The organization has a permanent laboratory and secretariat function (sometimes referred to as the Headquarters), the activities of which include the establishment of the basic standards and scales of the principal physical quantities and maintenance of the international prototype standards.

The CGPM acts on behalf of the governments of its members. In so doing, it elects members to the CIPM, receives reports from the CIPM which it passes on to the governments and national laboratories on member states, examines and where appropriate approves proposals from the CIPM in respect of changes to the International System of Units (SI), approves the budget for the BIPM (over €13 million in 2018) and it decides all major issues concerning the organization and development of the BIPM.

The structure is analogous to that of a stock corporation. The BIPM is the organization, the CGPM is the general meeting of the shareholders, the CIPM is the board of directors appointed by the CGPM, and the staff at the site in Saint-Cloud perform the day-to-day work.

Membership criteria The CGPM recognises two classes of membership – full membership for those states that wish to participate in the activities of the BIPM and associate membership for those countries or economiesAs of 2012, the only "economy" that was an associate member was CARICOM (Caribbean Community) – its membership comprising Antigua and Barbuda, Saint Kitts and Nevis, Barbados, Saint Lucia, Belize, Saint Vincent and the Grenadines, Dominica, Suriname, Grenada, Trinidad and Tobago and Guyana. Jamaica, although also a member of CARICOM, is an associate of the CGPM in its own right. that only wish to participate in the CIPM MRA program. Associate members have observer status at the CGPM. Since all formal liaison between the convention organizations and national governments is handled by the member state's ambassador to France,In the case of France, the French Foreign Minister it is implicit that member states must have diplomatic relations with France, though during both world wars, nations that were at war with France retained their membership of the CGPM. CGPM meetings are chaired by the Président de l'Académie des Sciences de Paris.

Of the twenty countries that attended the Conference of the Metre in 1875, representatives of seventeen signed the convention on 20 May 1875.Argentina, Austria-Hungary, Belgium, Brazil, Denmark, France, German Empire, Italy, Peru, Portugal, Russia, Spain, Sweden and Norway, Switzerland, Ottoman Empire, United States and Venezuela. In April 1884, H. J. Chaney, Warden of Standards in London unofficially contacted the BIPM inquiring whether the BIPM would calibrate some metre standards that had been manufactured in the United Kingdom. Broch, director of the BIPM replied that he was not authorised to perform any such calibrations for non-member states. On 17 September 1884, the British Government signed the convention on behalf of the United Kingdom. This number grew to 21 in 1900, 32 in 1950, and 49 in 2001. , there are 64 Member States and 37 Associate States and Economies of the General Conference (with year of partnership in parentheses):

Member states

Argentina (1877) Australia (1947) Austria (1875)Joined originally as Austria-Hungary Belarus (2020) Belgium (1875) Brazil (1921) Bulgaria (1911) Canada (1907) Chile (1908) China (1977) Colombia (2012) Costa Rica (2022) Croatia (2008) Czech Republic (1922)Joined originally as part of Czechoslovakia Denmark (1875) Ecuador (2019) Egypt (1962) Estonia (2021) Finland (1913) France (1875) Germany (1875)Joined originally as the German Empire Greece (2001) Hungary (1925)Joined originally as Austria-Hungary India (1880) Indonesia (1960) Iran (1975) Iraq (2013) Ireland (1925) Israel (1985) Italy (1875) Japan (1885) Kazakhstan (2008) Kenya (2010) Lithuania (2015) Malaysia (2001) Mexico (1890) Montenegro (2018) Morocco (2019) Netherlands (1929) New Zealand (1991) Norway (1875)Joined originally as part of Sweden and Norway Pakistan (1973) Poland (1925) Portugal (1876) Romania (1884) Russia (1875)Joined originally as the Russian Empire Saudi Arabia (2011) Serbia (2001) Singapore (1994) Slovakia (1922) Slovenia (2016) South Africa (1964) South Korea (1959) Spain (1875) Sweden (1875) Switzerland (1875) Thailand (1912) Tunisia (2012) Turkey (1875)Joined originally as the Ottoman Empire Ukraine (2018) United Arab Emirates (2015) United Kingdom (1884) United States (1878) Uruguay (1908)

Former members

Cameroon (1970–2012) Dominican Republic (1954–2015) North Korea (1982–2012) Peru (1875–1956) Venezuela (1879–1907, 1960–2018)

Notes

Associates At the 21st meeting of the CGPM in October 1999, the category of "associate" was created for states not yet BIPM members and for economic unions.

Albania (2007) Azerbaijan (2015) Bangladesh (2010) Bolivia (2008) Bosnia and Herzegovina (2011) Botswana (2012) Cambodia (2021) Caribbean Community (2005) Chinese Taipei (2002) Cuba (2000) Ethiopia (2018) Georgia (2008) Ghana (2009) Hong Kong (2000) Jamaica (2003) Kuwait (2018) Latvia (2001) Luxembourg (2014) Malta (2001) Mauritius (2010) Moldova (2007) Mongolia (2013) Namibia (2012) North Macedonia (2006) Oman (2012) Panama (2003) Paraguay (2009) Peru (2009) Philippines (2002) Qatar (2016) Sri Lanka (2007) Syria (2012) Tanzania (2018) Uzbekistan (2018) Vietnam (2003) Zambia (2010) Zimbabwe (2010–2020, 2022)

Former associates

Seychelles (2010–2021) Sudan (2014–2021)

CGPM meetings