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Convert between watts, kilowatts, horsepower, BTU/hour, and foot-pounds per minute. Essential for understanding motor ratings, electrical systems, HVAC sizing, and vehicle engine power.
Power is the rate at which energy is transferred or converted. The SI unit is the Watt (W). Different industries use different units: electrical systems use watts and kilowatts, automotive engineering uses horsepower, HVAC uses BTU/hour, and older mechanical systems use foot-pounds per minute.
1 kilowatt (kW) = 1,000 watts (W). Household appliances range from 5W (LED bulb) to 5,000W (electric oven). A typical home uses 1-5 kW average power. Solar panels are rated in kilowatts peak (kWp).
1 mechanical horsepower (hp) = 745.699 watts. The unit was coined by James Watt in the 18th century to compare steam engine output to horse-pulling power. A typical car engine: 100-400 hp = 75-300 kW. An electric motor is more efficient than a combustion engine in converting watts to mechanical power.
HVAC systems use BTU/hr for heating and cooling capacity. 1 BTU/hr = 0.293071 watts. A 10,000 BTU/hr window AC = 2,930 watts. Home furnaces range from 40,000 to 120,000 BTU/hr (11.7 to 35.2 kW).