There are seven units in the metric system: length, mass, time, electric current, temperature, amount of substance, and luminous intensity. The unit of length is the meter (m), the unit of mass is the kilogram (kg), the unit of time is the second (s), the unit of electric current is the ampere (A), the unit of temperature is the kelvin (K), the unit of amount of substance is the mole (mol), and the unit of luminous intensity is the candela (cd).