Free calculatorsElectricity
This category brings together electrical calculations for understanding an installation before choosing equipment, cable or power supply. You can connect power, voltage and current, estimate voltage drop, convert amp-hours and watt-hours, use Ohm’s law, estimate an inverter’s required power or turn electricity use into cost. Simply choose the subcategory that interests you, then open the tool you need.
Power & cables
Connect power, current and voltage, then check cable size and voltage drop.
Watts to Amps Calculator
Calculate amps from power in watts, voltage and power factor for single-phase or three-phase circuits.
Cable Size Calculator
Estimate cable cross-section from current, length and allowed voltage drop. This guide does not replace an installation safety assessment.
Voltage Drop Calculator
Calculate voltage loss in volts and percent along an electrical circuit.
Circuits & Ohm’s law
Calculate resistance and current from the voltage and power of a resistive load.
Batteries & backup
Convert capacity and energy, then estimate required UPS power.
Consumption & cost
Turn kWh into cost and estimate electric-heating use over time.