Common power units and conversions
1. SI units
Watt (W)
Definition: 1 Watt = 1 Joule/second (1 J/s).
Applications: electricity, electronic equipment, home appliances, etc.
Conversion:
1 kilowatt (kW) = 1000 watts (W)
1 megawatt (MW) = 1000 kilowatts (kW) = 1,000,000 watts (W)
1 gigawatt (GW) = 1000 megawatts (MW)
1 milliwatt (mW) = 0.001 watt (W)
2. Non-SI units
Horsepower (hp)
Classification:
Imperial horsepower (hp): 1 hp ≈ 745.7 W
Mainly used in the United Kingdom and the United States, such as car engine power.
Metric horsepower (PS, Pferdestärke): 1 PS ≈ 735.5 W
Commonly used in the automotive industry in Europe, Japan and other places.
Conversion:
1 hp ≈ 1.01387 PS
1 PS ≈ 0.9863 hp
British thermal unit per hour (BTU/h)
Definition: 1 BTU/h ≈ 0.293 W
Application: Heating, ventilation and air conditioning (HVAC), boiler power.
Conversion:
1 kW ≈ 3412 BTU/h
1 BTU/h ≈ 0.000293 kW
Calories per second (cal/s)
Definition: 1 cal/s ≈ 4.184 W
Application: Thermodynamic experiments, food energy calculations.
Foot-pounds per second (ft·lb/s)
Definition: 1 ft·lb/s ≈ 1.3558 W
Application: Power calculations in mechanical engineering (e.g. engine torque).
