Capacitor Energy Calculator
Find the energy stored in a capacitor with E = ½·C·V².
Energy in a capacitor
A charged capacitor stores energy in its electric field, and that energy scales with the square of the voltage across it. This calculator finds it from capacitance and voltage.
A 1 millifarad capacitor charged to 12 volts holds 0.072 joules. Double the voltage and the stored energy quadruples — which is why high-voltage capacitors demand respect even after power is removed.
Handy and private
It applies E = ½CV² in your browser, so nothing you enter is uploaded.
Frequently Asked Questions
How much energy does a capacitor store?
Half the capacitance times the voltage squared. Because voltage is squared, energy rises steeply as you charge to a higher voltage.
What units are used?
Capacitance in farads and voltage in volts give energy in joules.
What is it used for?
Sizing energy storage, flash circuits, and power-supply reservoirs, and gauging discharge hazards.
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