Power Converter
Convert between watts, kilowatts, megawatts, horsepower, and more power units.
Quick Reference β 1 unit = ? Kilowatt (kW)
| Unit | Value |
|---|---|
| Watt (W) | 0.001 |
| Kilowatt (kW) | 1 |
| Megawatt (MW) | 1000 |
| Gigawatt (GW) | 1000000 |
| Horsepower (mechanical) | 0.7457 |
| Horsepower (metric) | 0.735499 |
| BTU per Hour (BTU/h) | 0.00029307 |
| Calorie per Second (cal/s) | 0.004184 |
Formula
Multiply by (from factor / to factor)
Everyday Uses
Engine specs
European cars quote kW, American listings quote horsepower β convert (1 kW β 1.34 hp) to compare engines honestly.
AC and heating sizing
Air conditioners quote BTU/h, generators quote watts β convert power ratings so equipment matches the room.
Generator planning
Sum your devices' watt ratings and convert to kW or kVA to size a backup generator properly.
Fitness power
Cycling watts, treadmill horsepower, and calorie burn rates β convert power figures across your training tools.
Frequently Asked Questions
How many watts are in a horsepower, and what is the difference between mechanical and metric HP?
1 mechanical (imperial) horsepower = 745.7 watts. 1 metric horsepower (PS/CV) = 735.499 watts β about 1.4% less. The difference is small enough that most people use them interchangeably. Car engine power is often listed in both: a 200 PS engine = 200 Γ 0.7355 = 147.1 kW = 197.2 mechanical HP. The term "horsepower" was coined by James Watt in the 1780s to market steam engines β 1 HP was defined as the power of a horse lifting 33,000 pounds one foot per minute.
How do watts, kilowatts, and megawatts compare in real-world terms?
1 watt (W) = 1 joule/second. Power scale reference: LED bulb: 5β10 W. Human at rest: ~80 W. Human cycling hard: ~200β400 W. Kettle: 2β3 kW. Electric car motor: 50β300 kW. A 200 HP car engine = ~149 kW. Large wind turbine: 2β15 MW. Nuclear power plant unit: ~1,000β1,700 MW (1β1.7 GW). UK total electricity demand: ~30β40 GW. Lightning bolt: ~1β5 GW (for ~1 microsecond = very little total energy).
What is the difference between power and energy?
Power is the rate of energy transfer (watts = joules per second). Energy is the total amount transferred over time (joules, kWh). They are related by: Energy = Power Γ Time. A 1 kW heater running for 1 hour consumes 1 kWh of energy. A 2 kW heater running for 30 minutes also consumes 1 kWh. Electricity bills charge for energy (kWh, not kW). A high-power device (microwave: 1,000 W) used briefly may cost less than a lower-power device (fridge: 150 W) running continuously.
How do you convert horsepower to kilowatts for car comparisons?
kW = HP Γ 0.7457 (mechanical HP) or HP Γ 0.7355 (metric PS). To convert kW to HP: divide by 0.7457. Examples: 150 HP = 111.9 kW; 200 HP = 149.1 kW; 300 HP = 223.7 kW; 400 HP = 298.3 kW. Electric cars are usually rated in kW (or sometimes kW converted to HP for marketing): Tesla Model 3 Long Range = 283 kW = 379 HP. Torque is measured separately (in lb-ft or Nm) and is equally important for real-world performance.
What is BTU/hour and how is it used for air conditioners and heating?
1 BTU/h = 0.29307 watts. Air conditioning and heating capacity is traditionally rated in BTU/h in North America. Common AC sizes: 5,000 BTU/h = 1.47 kW (small room); 12,000 BTU/h = 3.52 kW = 1 "ton" of refrigeration (the cooling equivalent of melting one ton of ice per day); 24,000 BTU/h = 7 kW (large room/small house). Boilers and furnaces: a 100,000 BTU/h boiler = 29.3 kW. Europe uses kW for heating and cooling capacity instead of BTU/h.