International Bureau of Weights and Measures

The International Bureau of Weights and Measures (Bureau international des poids et mesures, in French), is an international standards organisation, one of three such organisations established to maintain the International System of Units (SI) under the terms of the Convention du Mètre (Metre Convention). The organization is usually referred to by its French abbreviation, BIPM.

It is based at the Pavillon de Breteuil in Sèvres, France, where it enjoys extraterritorial status. As such, it escaped German occupation during World War II.

The BIPM helps to ensure uniformity of SI weights and measures around the world. It does this with the authority of the Convention du Mètre, a diplomatic treaty between fifty-one nations (as of 2005), and it operates through a series of Consultative Committees, whose members are the national metrology laboratories of the Member States of the Convention, and through its own laboratory work.

The BIPM carries out measurement-related research. It takes part in, and organises, international comparisons of national measurement standards, and it carries out calibrations for member states.

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

The other organisations which maintain the SI system are the General Conference on Weights and Measures (CGPM, Conférence générale des poids et mesures) and the International Committee for Weights and Measures (CIPM, Comité international des poids et mesures)