Capacitor Energy Calculator
An ideal capacitor stores energy in its electric field. The energy depends quadratically on voltage, so doubling voltage at fixed capacitance multiplies stored energy by four.
How to use this calculator
- Enter capacitance in microfarads and the voltage actually across the component.
- Check that units, denominator definitions and time periods are consistent before comparing scenarios.
- Run a second scenario when an assumption is uncertain.
Formula used by capacitor energy calculator calculator
Stored energy (J) = 0.5 × capacitance (F) × voltage²; microfarads are converted to farads.
- Stored energy (J) = 0.5 × capacitance (F) × voltage²; microfarads are converted to farads.
- Real devices have voltage ratings, leakage, tolerance and parasitic effects. This tool does not make a circuit safe or select a suitable component.
- The tool performs arithmetic on the values entered and does not validate assumptions against outside records.
Worked examples
Worked example
220 µF charged to 24 V.
E = ½CV² = 0.5 × 220×10⁻⁶ × 24² = 0.06336 J.
Stored energy is approximately 0.06336 joules.
Understanding the result
An ideal capacitor stores energy in its electric field. The energy depends quadratically on voltage, so doubling voltage at fixed capacitance multiplies stored energy by four.
Real devices have voltage ratings, leakage, tolerance and parasitic effects. This tool does not make a circuit safe or select a suitable component.
Important notes
Real devices have voltage ratings, leakage, tolerance and parasitic effects. This tool does not make a circuit safe or select a suitable component.
Treat this output as an estimate tied to the stated inputs. For regulated, safety-critical, tax or professional decisions, verify applicable official guidance and specifications.
Frequently asked questions
Why is voltage squared?
The capacitor energy formula is one half of capacitance times voltage squared.
Can I safely discharge a capacitor based on this result?
No. Use the equipment manufacturer’s approved procedure and qualified assistance.
How should I interpret the result?
Real devices have voltage ratings, leakage, tolerance and parasitic effects. This tool does not make a circuit safe or select a suitable component.
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This page provides a calculation tool plus explanatory information so you can understand what the result means and when the underlying method may not fit your situation.