Electrical Calculators

Every electrical calculator on the site, grouped by the job. Each one shows the formula and the steps with your numbers, keeps its inputs in the link so you can share or repeat a result, and prints a dated record. Nothing you type is uploaded.

Power conversions

• Watts to amps calculator — watts to amps and amps to watts for DC, single-phase and three-phase circuits.
• kW to amps calculator — kilowatts to amps and back, including motor efficiency.
• kVA calculator — amps to kVA and kVA to amps, with transformer full-load currents.
• kVA to kW calculator — kVA, kW and kvar with the power factor.
• Three phase power calculator — three-phase kW, kVA, kvar and current, line and phase voltage.
• Power factor calculator — power factor, and the capacitor kvar and µF to correct it.
• Ohm’s law calculator — voltage, current, resistance and power from any two.

Wire and cable

• Voltage drop calculator — volts and percent drop for AWG or mm² copper and aluminum conductors.
• Wire size calculator — the smallest AWG or mm² size for a voltage-drop limit.
• DC wire size calculator — wire gauge for 12 V, 24 V and 48 V systems.
• Cable size calculator — minimum cable size in mm² by voltage drop, with mV/A/m.

System sizing

• Breaker size calculator — minimum rating and standard breaker size for loads and motors.
• Electrical load calculator — house load by the NEC 220.82 optional method and service size.
• Generator size calculator — generator kW and kVA from running and starting watts.
• Transformer sizing calculator — required kVA and the standard transformer size.
• Fault current calculator — available short-circuit current at a transformer and a feeder.

All results are estimates for planning: check conductor ampacity and code requirements in the applicable code (NEC, BS 7671, IEC 60364) and have critical designs verified. Results may be used freely in commercial work such as quotes, proposals and reports.