metrication

Metrication is the process of adopting the metric system of measurement, the decimal-based system that uses the International System of Units (SI). It involves replacing historical local or customary units with SI units in areas such as commerce, science, industry, and daily life. The transition aims to standardize measurements across sectors and borders.

The metric system originated in France in the late 18th century and was designed to be universal and decimal. It evolved into the International System of Units (SI), officially established in 1960 and maintained by the International Bureau of Weights and Measures (BIPM). SI defines seven base units—metre, kilogram, second, ampere, kelvin, mole, and candela—with most other units derived from these and scaled by decimal prefixes (milli-, centi-, kilo-, etc.). In 2019, the SI definitions were revised to anchor all seven base units to fixed fundamental constants, yielding stable, universally accessible standards.

Adoption varies by country and sector. The vast majority of nations use metric units in education, trade, science, and government regulation. The United States is frequently cited as not having completed metrication, with customary units such as inches, pounds, and gallons still common in everyday life, though metric units are widely used in science, medicine, and many industries. In some regions and sectors, non-metric units persist due to legacy practices and public familiarity.

The move toward metrication is usually gradual and requires regulatory changes, updates to educational materials, manufacturing processes, labeling, and infrastructure. Benefits include easier international trade, improved safety, and alignment with scientific standards; costs and public resistance during transition can pose challenges.