A capacitor stores electrical energy in an electric field.
Q = C × V (coulombs).
E = ½ × C × V² (joules).
τ = R × C (time constant — 63.2% charged in one τ).
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.
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.
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.
τ = RC. After one time constant, a capacitor charges to 63.2% of supply voltage.