Capacitor Energy Calculator
Calculate ideal stored energy, charge and farad value from capacitance in microfarads and voltage.
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Connect capacitor voltage to stored charge and energy
Enter capacitance in microfarads and voltage to calculate ideal stored energy in joules and charge in coulombs. The page also displays the converted capacitance in farads, making the scale factor visible before voltage is squared in the energy equation. This provides a quick classroom or early design check without assuming a particular capacitor technology.
Evaluate ratings, losses and discharge conditions separately
Usable energy can be lower because a load stops operating above zero volts, while equivalent series resistance and leakage create additional limits. High voltage or large capacitance can remain hazardous after power is removed. Confirm voltage rating, polarity, ripple, temperature, discharge path and manufacturer data rather than treating the ideal joule result as a safety assessment.
Frequently asked questions
Why does voltage have a large effect on energy?
Ideal stored energy is proportional to voltage squared.
Does the result include ESR losses?
No. It uses an ideal capacitor relationship.
Is zero capacitance allowed?
Yes mathematically, but it returns zero charge and energy and does not represent a useful component.