National Physical Laboratory

Key Organisations in World Metrology

The central coordination role for worldwide metrology is undertaken by the Bureau International des Poids et Mesures (BIPM), with individual countries represented by a well-established network of National Metrology Institutes (NMIs) and Designated Institutes (DIs). A brief explanation of the main organisations within the International Metrology scene is provided below.


Recognising the need to work towards internationally agreed measurement standards, in 1875 governments from 17 countries worldwide signed the Metre Convention. This treaty agreed to create and finance a permanent, scientific institute, the BIPM, as the centre for coordination of world measurement. The Comité International des Poids et Mesures (CIPM) was established to oversee the BIPM and today there are 58 Member States of the Metre Convention, and 41 Associate States and Economies of the General Conference.

Key steps by the BIPM and CIPM in the development of the international metrology system in operation today were the introduction of the SI system in 1960 and the establishment of the CIPM Mutual Recognition Arrangement in 1999.   

National Metrology Institute (NMI)

An NMI is an institute designated by national decision to develop and maintain national measurement standards for one or more quantities. An NMI represents the country internationally in relation to the NMIs of other countries, in relation to the Regional Metrology Organisations and to the Bureau International des Poids et Mesures (BIPM). NMIs are the backbone of the international metrology organisation.

Some countries have a single organisation as the NMI (e.g. NIST, the National Institute of Standards and Technology, is the NMI of the USA), whereas other countries have a more distributed system. In the UK NPL is the prime NMI laboratory and maintains the majority of the measurement standards, but there are five Designated Institutes laboratories which are responsible for particular measurement standards.

  • LGC maintains some of the chemical and biochemical standards
  • NEL maintains standards of flow
  • NIBSC - bio-activity metrology related to international activity units
  • NGML - gear standards
  • Regulatory Delivery, part of the Department for Business, Energy and Industrial Strategy - fluid flow: static volume and is also responsible for legal metrology

Visit the BIPM website to find links to other NMIs around the world.

Regional Metrology Organisation (RMO)

NMIs from the same part of the world are often members of a RMO, which coordinates activities between its members and also between other RMOs.

The RMO for European NMIs is EURAMET and NPL is an active member of this organisation

Further information on metrology and the international metrology system can be found in the booklet 'Metrology - In Short' available from EURAMET.

Last Updated: 6 Sep 2016
Created: 4 Oct 2007


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