World Metrology Day is a holiday that celebrates the signing of the Metre Convention in Paris on 20 May 1875. The international treaty was developed to coordinate the creation of a globally adopted standard for measurement of length and mass (the metric system). The development of the system was tasked to three organizations, the CGPM (General Conference of Weights & Measures), CIPM (International Committee for Weights & Measures), and the BIPM (International Bureau of weights & Measures). In 1921, all other forms of physical measurement were included.
As global trade began ramping up in the 1200’s, governments saw the need for uniformity of measurement. The 25th clause of the Magna Carta stipulated the need for a single measurement to be adopted. When England and Scotland were united in 1707, Scotland adopted the English measurement system. In the 1800s, the Czar of Russia adopted the system to facilitate trade. By the mid-1800s, many European countries began using the system.
Italian physicist and electrical engineer Giovanni Giorgi proposed the Giorgi system of measurement in 1901. The system built a set of units from four base units. The metre to measure length, the kilogram for mass, the second for time, and an electrical unit. In 1948, the system was overhauled and renamed the International System of Units. The kelvin was added as the temperature base unit and the candela for luminosity in 1954. The mole, commonly used in chemistry, became the base unit for amount of a substance in 1971.
While metric is the dominant measurement system globally, imperial units are still used in quite a few countries on specific items. Physical dimensions and freight scales skew heavily towards the imperial or standard system. The one area where the international system is the most prevalent is in temperature measurement.