World Metrology Day is an annual celebration of the signature of the Metre Convention on 20 May 1875 by representatives of seventeen nations.

Metrology, the science of measurement, plays a central role in scientific discovery and innovation, industrial manufacturing and international trade, in improving the quality of life and in protecting the global environment.

The theme for World Metrology Day 2026 is: Metrology: Building Trust in Policy Making.

A video message from the Director of the BIPM was recorded for this event.

More information on World Metrology Day website.