metric system: Quick Facts

Written and fact-checked by

The Information Architects of Encyclopaedia Britannica

Photos

Infographic comparing metric vs imperial systems: weight, volume, temperature, car speeds, length, height, track distances, and global usage.

See All Images and Interactives →

Topics

Today in History—April 5: The U.S. Joins the Metric System—Sort Of Why Doesn’t the U.S. Use the Metric System?metric versus Imperial converter unit International System of Units apothecaries’ weight avoirdupois weight troy weight Astronomical unit nautical mile calorie week kilogram month

Dig Deeper: More Articles That Discuss This Topic

measurement system: The metric system of measurement

Key People

Gaspard Monge, detail of an oil painting by Jean Naigeon, 1811; in the Museum of Fine Arts, Beaune, France.

Gaspard Monge, count de Péluse

French mathematician and public official

Lagrange, Joseph-Louis, comte de l'Empire

Joseph-Louis Lagrange, comte de l’Empire

French mathematician

barometer. Antique Barometer with readout. Technology measurement, mathematics, measure atmospheric pressure

Fun Facts of Measurement & Math