Use for questions about standards of measurement used for different types of quantities, and for conversions between units.

Units are standards for measurement of physical quantities. Metrology is the science of developing nationally and internationally accepted units of measurement.

The most abundant unit system SI (Système international d'unités), consisting of seven seven base units: meter (length), kilogram (mass), second (time), ampere (current), kelvin (temperature), candela (luminous intensity), and mole (amount of substance). Units for other quantities are derived from these.