Capacitor Calculator

A capacitor stores electrical energy in an electric field.

What this calculator does

Q = C × V (coulombs).

How it works

E = ½ × C × V² (joules).

τ = R × C (time constant — 63.2% charged in one τ).

When to use this calculator

Reach for this calculator when a quick, verified engineering computation is needed without opening specialised software. The formula used follows the relevant standard and is documented for reference.

Common mistakes

A frequent mistake is using nominal or rated values when actual measured values are required. Calculations based on nominal dimensions or catalogue specifications may not match field conditions — always use measured values where precision matters.

Real-world scenarios

A mechanical engineer verifies a beam's deflection under a specified load using standard formulas. Running the calculation with exact dimensions confirms the design meets deflection limits before fabrication — catching an issue that would be expensive to correct in the field.

Frequently asked questions

What is RC time constant?

τ = RC. After one time constant, a capacitor charges to 63.2% of supply voltage.

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