Capacitor Charge & Energy Calculator
Calculate the charge and stored energy of a capacitor from capacitance and voltage.
Assumptions used in this calculation
- Ideal capacitor: Assumes an ideal capacitor with no equivalent series resistance or leakage current.
About this calculator
A capacitor's datasheet gives you capacitance in microfarads, but that number alone doesn't tell you how much charge it can deliver or how much energy it actually stores at your working voltage, and because stored energy scales with the square of voltage rather than linearly, a rough mental estimate can be off by a wide margin, which matters when you're dealing with capacitors large enough to deliver a dangerous discharge. This calculator takes a capacitor's capacitance and the voltage across it, then computes the stored charge (Q = C × V, in coulombs) and stored energy (E = ½ × C × V², in joules) directly from the two defining capacitor equations. It's useful for sizing capacitors in power-supply filtering, flash circuits, or energy-storage applications, estimating how much energy a charged capacitor could discharge before you handle it, or simply understanding how capacitance and voltage trade off against each other, without deriving the energy integral from scratch.
Worked example
100µF at 12V
Result: 7.2 mJ, 1200 µC
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