Capacitor Energy Calculator
Calculate energy stored in a capacitor.
Formula
E = ½CV².
What Is Capacitor Energy?
A charged capacitor stores electrical potential energy in its electric field. The ideal stored energy is E = ½CV², so voltage has a particularly strong effect because it is squared.
Example Calculation
A 0.001 F capacitor charged to 12 V stores 0.5 × 0.001 × 12² = 0.072 J.
Factors That Affect the Result
Energy increases directly with capacitance and with the square of voltage. Doubling voltage quadruples stored energy. Real capacitors have voltage ratings, leakage, ESR and tolerances that can limit practical behavior.
Interpreting the Result
The result is ideal stored energy in joules. Even modest capacitance can store significant energy at high voltage, so actual circuits must respect component ratings and safe discharge practices.
Frequently Asked Questions
Why is voltage squared?
Capacitor voltage rises as charge is added, and integrating the charging work produces the V² term.
What unit is capacitance?
The SI unit is the farad.
Does a disconnected capacitor keep its energy?
Ideally yes, but real capacitors slowly lose charge through leakage.
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Formula and Practical Limits
Stored capacitor energy is E = ½CV². Because voltage is squared, increasing voltage has a strong effect on stored energy. Use rated component limits and appropriate circuit safety practices in real hardware.