Wattless current is a type of current that occurs in an AC circuit when the average power consumed is equal to zero. It is also known as idle current. In an AC circuit containing only an inductor or capacitor, the current flowing in the circuit is said to be wattless if the average power consumed in the circuit is zero. The formula used for calculating the wattless current is P = VIcosφ, where P is the power in watts, V is the voltage in volts, I is the current in amperes, and φ is the phase difference between voltage and current when only an inductor or capacitor is present in the circuit. When the phase difference is π/2, there is no power consumption, and this is referred to as wattless current.