Parallel Resistor Calculator
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Energy
Capacitor Calculator
Find the energy and charge stored in a capacitor.
Energy stored
—
Joules.
| Charge | — |
|---|---|
| Capacitance | — |
| Voltage | — |
| — |
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Enter your figures above to see the step-by-step working.
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How the Capacitor Calculator Works
A charged capacitor stores energy in its electric field. The energy is one-half the capacitance times the voltage squared, and the charge it holds is capacitance times voltage. A 1,000 µF capacitor at 12 volts stores about 0.072 joules and holds 0.012 coulombs of charge.
Capacitance is entered in microfarads (µF) and converted to farads for the math. Because voltage is squared, a higher voltage stores far more energy — which is why large capacitors at high voltage can be dangerous even after the power is off.
energy = ½ × capacitance × voltage²
Frequently Asked Questions
How much energy does a capacitor store?
One-half the capacitance (in farads) times the voltage squared, giving joules. Voltage matters most because it’s squared.
What is the charge on a capacitor?
Capacitance times voltage, measured in coulombs. A 1,000 µF cap at 12 V holds 0.012 C.
Why can charged capacitors be dangerous?
They can hold significant energy at high voltage even after power is removed, and discharge it all at once. Large ones should be bled off through a resistor.
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