World Metrology Day - 20 May 2025, Measurement for all times, for all people

World Metrology Day is an annual celebration of the signing of the Metric Convention on 20 May 1875 by representatives of seventeen nations. The Convention established a framework for global cooperation in metrology and its industrial, commercial and societal applications. The original goal of the Metric Convention was broad global uniformity of measurement, which remains as important today as it was in 1875.

This year's commemoration of the 150th anniversary aims to highlight the importance of international cooperation in metrology and its impact on the past, present and future of measurement. The theme of World Metrology Day is therefore Measurement for all times, for all people.

The World Metrology Day project is jointly implemented by the International Bureau of Weights and Measures and the International Organization for Legal Metrology. For more information, please see here.

In November 2023, 20 May was officially declared World Metrology Day by UNESCO. For more information, see here.

On the occasion of the World Metrology Day, the Czech Metrology Institute organizes open day.