How Do You Convert Amps to Watts?


In general, watts are calculated by taking the current, in amps, and multiplying by the voltage. AC currents involve additional steps, which may include multiplying by a power factor (for single-phase currents) or multiplying by a power factor and a coefficient (for three-phase currents).

Single-phase and three-phase currents are distinguished by how the power is distributed, with single-phase systems supplying all of the voltages in unison while three-phase systems supply the voltages in three sequential stages. In three-phase currents, if the voltage is taken from line to line, the coefficient is the square root of three. If the voltage is measured from the line to a neutral ground, then the coefficient is simply three. The power factor is the ratio of the measured power in the line to the theoretical power supplied to the circuit.