Electrical Calculators

Ohm's law, power, wire size, voltage drop and battery runtime.

19 calculators in this category.

Power & load

Amps to Watts Calculator — Convert current in amps to power in watts for AC or DC circuits.
Electrical Power Calculator — Calculate real, apparent and reactive power for single or three-phase supplies.
Generator Size Calculator — Size a standby generator for running and starting loads.
Inverter Size Calculator — Size an inverter for continuous and surge loads with headroom.
Power Factor Calculator — Calculate power factor and the correction capacitance needed to improve it.
Watts to Amps Calculator — Convert power in watts to current in amps for AC or DC circuits.

Ohm's Law Calculator — Solve for voltage, current, resistance or power from any two known values.
Resistor Calculator — Calculate series and parallel resistance, and voltage divider outputs.
Three-Phase Power Calculator — Calculate three-phase power, current and line values for star or delta.
Voltage Drop Calculator — Calculate voltage drop over a cable run and check it against limits.
Volts to Watts Calculator — Calculate power from voltage with either current or resistance.

Appliance Running Cost Calculator — Compare the running cost of several appliances side by side.
Electricity Bill Calculator — Estimate a full electricity bill including tiered rates, standing charge and tax.
Electricity Cost Calculator — Calculate the running cost of any appliance by hour, day, month and year.
kWh Calculator — Convert between watts, kilowatts, kilowatt-hours and energy cost.

Battery Capacity Calculator — Size a battery bank for a required runtime and load.
Battery Runtime Calculator — Calculate how long a battery will power a load, allowing for depth of discharge.
Motor Current Calculator — Calculate full-load and starting current for an electric motor.
Wire Size Calculator — Estimate cable cross-section from voltage drop and load — a planning figure, not a compliant selection.