25 FREE TOOLS
Engineering & Electrical calculators
Estimate electrical quantities, power and equipment requirements with the formula and load assumptions shown.
← All calculators
Ohm’s Law Calculator
Use voltage and current to calculate resistance and resistive power.
Electrical Power Calculator
Calculate single-phase real electrical power with an entered power factor.
Voltage Drop Calculator
Estimate resistive voltage drop along a cable from length and conductor area.
Current Calculator
Calculate single-phase current from real power, voltage and power factor.
Resistance Calculator
Find electrical resistance from the voltage and current.
Watt to Amp Calculator
Convert watts to amperes for a DC or unity-power-factor load.
Amp to Watt Calculator
Convert amperes to watts for a DC or resistive load.
kW to HP Calculator
Convert kilowatts into mechanical horsepower.
HP to kW Calculator
Convert mechanical horsepower into kilowatts.
Power Factor Calculator
Compare real and apparent power to calculate power factor.
Electricity Consumption Calculator
Estimate electrical energy use from wattage, running time and load factor.
Solar Panel Size Calculator
Estimate a solar array's size from daily energy demand and sunlight assumptions.
Battery Backup Calculator
Estimate battery runtime from usable stored energy and connected load.
Inverter Battery Calculator
Estimate inverter-battery backup after discharge and efficiency allowances.
UPS Runtime Calculator
Estimate UPS runtime using battery capacity and the load you enter.
Wire Size Calculator
Estimate conductor area from voltage-drop and current-density limits.
Transformer Calculator
Calculate ideal transformer voltage and current ratios from winding turns.
3-Phase Power Calculator
Calculate balanced three-phase real power from line voltage and current.
Frequency/Wavelength Calculator
Find wavelength from frequency and an entered wave-propagation speed.
Resistor Color Code Calculator
Read a four-band resistor's resistance and tolerance from its colours.
LED Resistor Calculator
Estimate a series resistor for an LED and check its power dissipation.
Capacitance Calculator
Calculate capacitance from electric charge and potential difference.
Inductance Calculator
Estimate inductance from voltage and a change in current over time.
Heat Load Calculator
Estimate room heat load from area, occupants and equipment.
AC Tonnage Calculator
Convert a preliminary cooling-load estimate into refrigeration tons.
