Electrical conversion calculators.
Watts, amps, kVA, Ohm's law, voltage drop, battery capacity — the fast, accurate conversions. Every one also tells you the NEC wire and breaker the result needs, not just the number.
Power & Current
Watts ↔ Amps
Convert watts to amps (or amps to watts) for DC, single-phase, and three-phase — plus the NEC wire and breaker the result needs.
Open converterkW ↔ Amps
Convert kilowatts to amps (or amps to kW) for DC, single-phase, and three-phase circuits, with the matching NEC wire and breaker size.
Open converterVolts ↔ Watts
Convert volts to watts (or watts to volts) using the current — watts = volts × amps — for DC, single-phase, and three-phase, with the NEC wire and breaker.
Open converterWatts ↔ kW
Convert watts to kilowatts and back. 1 kW = 1,000 W. Enter watts or kilowatts to see the other instantly.
Open converterMW ↔ kW
Convert megawatts to kilowatts and watts (or back) — a power-unit conversion. 1 MW = 1,000 kW = 1,000,000 W. For utility, solar, and generator capacity.
Open converterHP ↔ kW
Convert horsepower to kilowatts (or kW to HP) for motors, pumps, and generators — with the estimated current draw and the NEC wire and breaker it points to.
Open converterkVA → Amps
Convert kVA to amps (full-load current) for single- and three-phase systems — and the breaker and wire to feed it. For transformers and generators.
Open converterkVA ↔ kW
Convert kVA to kW (or kW to kVA) using the power factor — apparent vs real power for generators, transformers, and UPS systems.
Open converterHP ↔ Amps
Convert horsepower to amps (or amps to HP) for motors — by voltage, efficiency, and power factor — with the NEC wire and breaker the current needs.
Open converterkW ↔ HP
Convert kilowatts to horsepower — mechanical, electrical, and metric HP side by side — plus the motor input kW and full-load amps at 120V, 240V, and 480V.
Open converterAmps ↔ kW
Convert amps to kilowatts for DC, single-phase, and three-phase circuits with power factor — plus the NEC breaker and copper wire the current needs.
Open converterVolts ↔ Amps
Convert volts to amps using resistance (Ohm's law) or power (watts), for DC and AC — with the NEC breaker and wire size for the resulting current.
Open converterWatts ↔ Volts
Convert watts to volts using current (V = W ÷ A) or resistance (V = √(W × R)), for DC, single-phase, and three-phase — with the nearest standard system voltage.
Open converterKilowatts ↔ Watts
Convert kilowatts to watts (1 kW = 1,000 W) across the full SI ladder — milliwatts to gigawatts — with real appliance and equipment examples at each scale.
Open converterCircuit Design
Ohm's Law
Solve volts, amps, ohms, and watts from any two values using the full Ohm's law power wheel — with the wire ampacity for the resulting current.
Open converterVoltage Drop
Calculate voltage drop and percentage over a wire run, and get the smallest wire gauge that keeps you under the NEC 3% recommendation.
Open converterAmps ↔ kVA
Convert amps to kVA for single-phase and three-phase — plus the next standard transformer size up and the real kW the load delivers at your power factor.
Open converterkW ↔ kVA
Convert kW to kVA at any power factor, with the next standard generator and transformer size up — the rating you actually have to buy for the load.
Open converterBattery
Ah ↔ kWh
Convert battery amp-hours to kWh (and back), with usable capacity after depth-of-discharge and efficiency — plus runtime for a given load.
Open convertermAh ↔ Wh
Convert mAh to Wh (or Wh to mAh) for batteries and power banks using the voltage — Wh = mAh × V ÷ 1,000. Check airline limits in watt-hours.
Open converterEnergy & HVAC
Watts ↔ kWh
Convert watts to kilowatt-hours (or kWh to watts) by run time — turn an appliance's wattage into the energy it uses, the unit your utility bills.
Open converterBTU ↔ kW
Convert BTU/hr to kW, watts, and refrigeration tons (or kW back to BTU) for heat pumps, AC, and furnaces — compare heating and cooling output across units.
Open converterMWh ↔ kWh
Convert megawatt-hours to kilowatt-hours and back — plus watt-hours and gigawatt-hours. 1 MWh = 1,000 kWh. Enter any energy unit to see the rest.
Open converterkWh ↔ MWh
Convert kilowatt-hours to megawatt-hours — MWh = kWh ÷ 1,000 — plus watt-hours and gigawatt-hours. For utility data, solar production, and grid-scale figures.
Open converterBTU ↔ kWh
Convert BTU to kWh and back — plus therms and MMBtu. Energy-unit conversion (1 kWh = 3,412 BTU) for comparing gas and electric energy use.
Open converterkW ↔ kWh
Convert kilowatts to kilowatt-hours (or kWh back to kW) by run time — turn a device's power in kW into the energy it uses. kWh = kW × hours.
Open converterWatts ↔ Joules
Convert watts to joules (power × time) and convert between joules, kilojoules, watt-hours, kWh, and calories. 1 watt for 1 second = 1 joule.
Open converterTherms ↔ kWh
Convert therms of natural gas to kWh (or back) — plus BTU, ccf, and MMBtu. 1 therm = 100,000 BTU ≈ 29.3 kWh. Compare gas and electric energy.
Open converterkWh ↔ Watts
Convert kWh to watts by dividing energy over the hours it ran — the reverse meter-reading math — with the appliance that matches the resulting draw.
Open converterkWh ↔ kW
Convert kWh to kW over a run time, and see why utilities bill energy (kWh) and demand (kW) separately — including what a demand charge costs.
Open converterkW ↔ BTU/h
Convert kW to BTU per hour (1 kW = 3,412 BTU/h) and to tons of cooling — with the HVAC equipment size that matches the result.
Open converterkWh ↔ BTU
Convert kWh to BTU (1 kWh = 3,412.14 BTU) plus therms, ccf, and MMBtu — and compare what the same energy costs as electricity versus natural gas.
Open converterkWh ↔ Therms
Convert kWh to therms of natural gas (1 therm = 29.3 kWh) and compare the cost of the same heat delivered by gas, resistance electric, or a heat pump.
Open converterJoules ↔ Watts
Convert joules to watts by dividing energy over time (W = J ÷ s), with seconds, minutes, or hours — plus the kWh, BTU, and calorie equivalents.
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