Capacitor Energy Calculator Formula
Understand the math behind the capacitor energy calculator. Each variable explained with a worked example.
Formulas Used
Stored Energy
energy_j = 0.5 * cap_f * pow(voltage_v, 2)Stored Energy (mJ)
energy_mj = 0.5 * cap_f * pow(voltage_v, 2) * 1000Variables
| Variable | Description | Default |
|---|---|---|
capacitance_uf | Capacitance(µF) | 1000 |
voltage_v | Voltage(V) | 25 |
cap_f | Derived value= capacitance_uf / 1000000 | calculated |
How It Works
Capacitor Energy Storage
E = 0.5 x C x V^2
Energy scales with the square of voltage, so doubling voltage quadruples energy.
Worked Example
1000 uF capacitor at 25 V.
capacitance_uf = 1000voltage_v = 25
- 01C = 1000 uF = 0.001 F
- 02E = 0.5 x 0.001 x 25^2 = 0.5 x 0.001 x 625 = 0.3125 J
Frequently Asked Questions
Why does energy depend on V squared?
Each incremental charge requires more work as the voltage across the capacitor increases, leading to the V^2 relationship.
Can capacitors replace batteries?
Supercapacitors can for short-term storage but have much lower energy density than batteries.
Is this energy dangerous?
Even small capacitors at high voltage can deliver a painful or dangerous shock. Always discharge before handling.
Ready to run the numbers?
Open Capacitor Energy Calculator