Power converter

Watts to kilowatts and megawatts

The watt is the SI unit of power. The prefixes kilo-, mega- and giga- mean one thousand, one million and one billion, so conversions between these units are exact powers of ten.

Horsepower to kW and kW to horsepower

Mechanical horsepower, normally written hp, equals exactly 745.6998715822702 W under the international foot, pound and standard-gravity definitions. Metric horsepower, written PS, CV or sometimes simply hp in European vehicle specifications, equals exactly 735.49875 W.

The difference is about 1.4%. If a specification gives only a number without identifying the horsepower standard, check the manufacturer or source before converting it.

Power conversion formula

The calculator first converts the input to watts and then divides by the number of watts in the target unit. The general formula is P₂ = P₁ × f₁ ÷ f₂, where f₁ and f₂ are the source and target factors in watts.

• Watts to kilowatts: divide by 1,000. For example, 2,500 W ÷ 1,000 = 2.5 kW.
• Kilowatts to watts: multiply by 1,000. For example, 3.2 kW × 1,000 = 3,200 W.
• Megawatts to kilowatts: multiply by 1,000. For example, 2.5 MW = 2,500 kW.
• Mechanical horsepower to kilowatts: multiply by 0.7456998715822702. For example, 10 hp ≈ 7.456999 kW.

Power is different from energy

Watts and kilowatts measure the rate at which energy is transferred or used. Watt-hours and kilowatt-hours measure an amount of energy over time. A power value in kW therefore cannot be converted to kWh unless a duration is known.

If a 2 kW device runs at that power for 3 hours, it uses 2 kW × 3 h = 6 kWh. This converter changes units of power only; it does not estimate electricity consumption or cost.