The volt (symbol: V) is the SI derived unit of electric potential difference. The number of volts is a measure of the strength of an electrical source in the sense of how much power is produced for a given current level. It is named in honor of Alessandro Volta (1745 to 1827), who invented the voltaic pile, the first chemical battery.

The volt is defined as the potential difference across a conductor when a current of one amp dissipates one watt of power. Hence, it is the base SI representation m2 · kg · s-3 · A-1, which can be equally represented as one joule of energy per coulomb of charge, J/C.

1 V = 1 W/A = 1 m2·kg·s–3·A–1