The need for accurate measurements is evident throughout history and important steps for international metrology were the establishment of internationally agreed measurement units and standards and the methodology to enable recognition of the measurement standards of National Metrology Institutes and Designated Institutes around the world.

1875 - Metre Convention
Recognising the need to work towards internationally agreed measurement standards, in 1875 governments from 17 countries worldwide signed this treaty and agreed to create and finance a permanent, scientific institute, the Bureau International des Poids et Mesures (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 51 Member States of the Metre Convention, and 23 Associate States and Economies of the General Conference.

Visit the BIPM website for further details

1960 - SI units Established
The name Système International d'Unités (SI) was adopted in 1960 for the recommended practical system of units of measurement. There are 7 base units (metre, kilogram, second, ampere, kelvin, mole, and candela) and many derived units are formed by combining base units (e.g. volt, watt, newton, pascal, joule)

Find out more about the SI units

1999 - CIPM Mutual Recognition Arrangement (MRA)
This international arrangement was established in response to a growing need for an open, transparent and comprehensive scheme to provide users with reliable quantitative information on the comparability of national metrology services and to provide the technical basis for wider agreements negotiated for international trade, commerce and regulatory affairs.

In 1999, the directors of the national metrology institutes (NMIs) of 38 Member States of the Metre Convention and representatives of 2 international organisations signed a Mutual Recognition Arrangement for national measurement standards and for calibration and measurement certificates issued by NMIs.

Find out more about the CIPM MRA