Capacitor Energy Calculator

This Capacitor Energy Calculator works out how much energy a charged capacitor stores using the standard relationship E equals one half times capacitance times voltage squared. You enter the capacitance in farads and the voltage across the capacitor in volts, and the tool returns the stored energy in joules. Because the energy depends on the square of the voltage, doubling the voltage stores four times the energy, which is why voltage rating matters so much in real designs. The result is useful for anyone studying physics or electronics, designing power supplies, sizing energy storage banks, planning camera flash circuits, or checking discharge safety before working on equipment. A charged capacitor can deliver its stored energy very quickly, so even a modest figure in joules can give a sharp shock or damage components, which is why bench supplies and high voltage gear should always be discharged through a suitable resistor before handling. A few tips keep your numbers right. First, convert your capacitance to farads before entering it, since most components are labelled in microfarads, nanofarads or picofarads, and a microfarad is one millionth of a farad. Second, use the actual working voltage rather than the maximum rating, because the stored energy reflects the real charge on the plates. Third, remember the half in the formula, as leaving it out doubles your answer and is a very common mistake. Used carefully, this calculator gives a quick and reliable estimate of stored energy that you can use for design choices, capacity planning and safety checks alike.

Energy E = 0.5 x C x V squared, with C in farads and V in volts, giving joules.