Capacitor Energy Calculator

About this calculator

This calculator applies the formula E = ½CV² to find the energy stored in a capacitor (in joules) from its capacitance (farads) and the voltage across it, and separately computes the stored charge using Q = CV (coulombs).

Electronics students use it for circuit theory homework, while hobbyists and engineers use it to size capacitors for power-supply filtering, camera flash circuits, and energy-storage applications where knowing exactly how much energy a capacitor can release matters for both performance and safety. Because energy scales with the square of voltage, the calculator makes clear why doubling a capacitor's rated voltage quadruples its stored energy rather than just doubling it.