Capacitor Energy and Charge Calculator
Compute the electric charge and energy stored in a capacitor from its capacitance and the voltage across it.
F
V
Energy = ½ × C × V²
- 1
Stored charge
Q = 0.001 × 12 = 0.012Q = C × V (coulombs) - 2
Stored energy
½ × 0.001 × 12² = 0.072000
How does this calculator work?
A capacitor stores charge Q = C × V coulombs and energy E = ½ × C × V² joules, where C is capacitance in farads and V is the applied voltage. Energy can also be written ½ × Q × V. Because energy depends on voltage squared, doubling the voltage quadruples the stored energy.
Formula
How this is calculated
Enter the capacitance C in farads (F) and the voltage V in volts (V) applied across the capacitor. Because real components are often rated in microfarads (µF) or nanofarads (nF), convert to farads first: 1 µF = 1×10⁻⁶ F and 1 nF = 1×10⁻⁹ F.
The stored charge is Q = C × V, measured in coulombs (C). The energy stored in the electric field of the capacitor is E = ½ × C × V², which can equivalently be written E = ½ × Q × V since Q = C × V. Energy is reported in joules (J). The factor of one-half arises because the voltage rises linearly from 0 to V as charge accumulates, so the average voltage during charging is V/2.
These ideal relationships assume a linear capacitor with constant capacitance, no leakage, and a steady applied voltage. Negative capacitance is rejected as unphysical; a voltage of zero yields zero charge and zero stored energy. Doubling the voltage quadruples the stored energy because energy scales with V².
Frequently asked questions
As a capacitor charges, the voltage builds up gradually from zero to its final value, so the average voltage doing work is half the final voltage. Combining this with Q = C × V gives E = ½ × C × V², making energy proportional to V².
Convert to farads before entering it. Multiply microfarads by 0.000001 (for example, 100 µF = 0.0001 F) or nanofarads by 0.000000001, then type the farad value into the capacitance field.
Charge Q (in coulombs) is the amount of separated electric charge stored on the plates, equal to C × V. Energy E (in joules) is the work stored in the electric field, equal to ½ × C × V². They are related by E = ½ × Q × V.
Also known as
TG we-Calculate Editorial Team. (2026). Capacitor Energy and Charge Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/capacitor-energy-calculator
TG we-Calculate Editorial Team. "Capacitor Energy and Charge Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/capacitor-energy-calculator.
TG we-Calculate Editorial Team, "Capacitor Energy and Charge Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/capacitor-energy-calculator
@misc{wecalculate_capacitor_energy_calculator, title = {Capacitor Energy and Charge Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/capacitor-energy-calculator}}, year = {2026}, note = {TG we-Calculate} }
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