Convert Power Units
Power Converter
Power Conversion Chart
Key relationships between power units. The SI unit is the watt (W), defined as one joule per second.
SI / Metric
| 1 kW | = | 1,000 W | exact |
| 1 MW | = | 1,000,000 W | exact |
| 1 GW | = | 1,000,000,000 W | exact |
| 1 mW | = | 0.001 W | exact |
Horsepower Variants
| 1 hp (electric) | = | 746 W | exact |
| 1 hp (mechanical) | = | 745.6999 W | |
| 1 hp (metric/PS/CV) | = | 735.499 W | |
| 1 hp (boiler) | = | 9,809.5 W |
Thermal / HVAC
| 1 BTU/h | = | 0.29307 W | |
| 1 ton (refrig) | = | 12,000 BTU/h | exact |
| 1 ton (refrig) | = | 3,516.85 W | |
| 1 kcal/h | = | 1.163 W |
Electric hp = 746 W exactly (IEEE). Mechanical hp = 550 ft·lbf/s ≈ 745.7 W. Metric hp (PS/CV) = 75 kgf·m/s ≈ 735.5 W. Always specify which horsepower variant — they differ by up to 1.4%.
About Power Units
Electrical
Appliances are rated in watts (W) or kilowatts (kW). A typical LED bulb uses 10 W, a microwave 1,000 W (1 kW), an electric car charger 7–22 kW. Power plants are rated in megawatts (MW) or gigawatts (GW). 1 GW can power about 750,000 homes.
Motors & Mechanical
Engine power is rated in horsepower (hp). Cars in the US use mechanical hp; European specs often use metric hp (PS/CV). Electric motors use electric hp (746 W exactly). When comparing specs, check which hp variant is used.
HVAC & Thermal
Heating and cooling capacity uses BTU/h (US) or kW (metric). Air conditioners are rated in tons of refrigeration (1 ton = 12,000 BTU/h). A typical home AC unit: 2–5 tons (24,000–60,000 BTU/h = 7–17.6 kW).
Do not confuse kW (power) with kWh (energy). Power is the rate of energy use; energy is the total consumed. Running a 2 kW heater for 3 hours uses 6 kWh of energy.
Popular Power Conversions
Electrical (W, kW, MW)
Motors / Horsepower
HVAC / Thermal
Frequently Asked Questions
What is the difference between watts and kilowatts?
A kilowatt (kW) equals 1,000 watts (W). Watts measure small power levels like light bulbs (10W LED) and phone chargers (5-20W), while kilowatts measure larger loads like appliances (1-3 kW), EV chargers (7-22 kW), and solar systems (5-10 kW). To convert, divide watts by 1,000.
How do I convert horsepower to watts?
One mechanical horsepower equals 745.7 watts. Multiply the horsepower value by 745.7 to get watts, or divide by 1,000 to get kilowatts. For example, a 200 HP engine produces about 149 kW. Electrical horsepower is slightly different at exactly 746 watts.
What is the difference between kW and kWh?
kW (kilowatt) measures instantaneous power — how fast energy is being used right now. kWh (kilowatt-hour) measures total energy consumed over time. A 2 kW heater running for 3 hours uses 6 kWh. Think of kW as speed and kWh as distance. Electricity bills are charged per kWh.
How much power does a typical home use?
The average US household uses about 1.2 kW continuously (10,500 kWh per year divided by 8,760 hours). Peak demand can reach 5-10 kW when multiple appliances run simultaneously. A typical home solar system is sized at 6-10 kW to offset this consumption.
Conversion Charts & Tables
Printable charts and reference tables for power conversions:
Related Converter Categories
- Energy Converter — Energy = power × time (kWh = kW × h)
- Frequency Converter — Motor power at given RPM
