World Metrology Day – 20 May 2026, Metrology: Building trust in policy-making

World Metrology Day, which is celebrated annually on 20 May, was proclaimed in 1999 by the International Committee for Weights and Measures (CIPM) to commemorate the signing of the Metre Convention on 20 May 1875 in Paris – an agreement that laid the foundations for a globally uniform and evolving metric system.

The aim of World Metrology Day is to highlight the vital role of the science of measurement in our everyday lives. Metrology ensures the consistency and reliability of measurements and data used every day around the world, both in everyday life and in science and its applications – from GPS navigation and the determination of medical radiation doses to the safety of buildings. The metric system is therefore essential for global cooperation.

The World Metrology Day project is organised jointly by the International Bureau of Weights and Measures (BIPM) and the International Organisation of Legal Metrology (OIML). For further information, please visit here.

In November 2023, 20 May was officially designated World Metrology Day by UNESCO. In line with UNESCO’s mission to advance science for a better world, the aim of this day is to promote the impact of metrology on quality of life and environmental protection. For more information, please visit here.

Every year on this day, national metrology institutes, legal metrology bodies, regional organisations and the professional community in more than 50 countries celebrate.

The theme of this year’s World Metrology Day is „Metrology: Building trust in policymaking“.