What is the SI base unit of electric current?

The ampere is the SI base unit of electric current.

The ampere, symbol A, measures the rate at which electric charge flows through a circuit. Since 2019, the International System of Units defines it by fixing the numerical value of the elementary charge at exactly 1.602176634 × 10⁻¹⁹ coulomb.

An electric current of one ampere corresponds to the movement of one coulomb of charge per second. The unit is named after André-Marie Ampère, a French physicist and mathematician whose work helped establish electrodynamics.

A volt measures electric potential difference, an ohm measures electrical resistance and a coulomb measures electric charge. These related units are often mixed up, but only the ampere is the SI base unit for current. In circuit calculations, current is commonly represented by the letter I.