Capacitor Charge Calculator

About this calculator

This calculator finds the charge stored on a capacitor, Q = C·V, and the energy stored in its electric field, E = ½·C·V², from its capacitance C and the voltage V applied across it. Charge scales linearly with voltage, but stored energy scales with the square of voltage, since energy is the integral of voltage times the incremental charge added as the capacitor charges up from zero.

Electronics engineers use these formulas to design power-supply filtering and smoothing circuits, camera-flash circuits (which charge a capacitor slowly then discharge it almost instantly for a bright flash), and defibrillators, which store a precise, life-critical amount of energy in a capacitor bank before delivering a shock. Electrical engineering students, electronics hobbyists building circuits, and technicians troubleshooting power-supply capacitors use this calculator to check charge and energy figures against a component's rated capacitance and voltage.