How many watts are in one horsepower?

One mechanical horsepower equals exactly 745.69987 watts, commonly rounded to 745.7 W. This is the standard definition of horsepower used for engine and motor ratings in most countries. Electric horsepower is slightly different at 746 W exactly.

What is BTU per hour?

BTU per hour (BTU/hr) is a unit of power measuring how many British Thermal Units of energy are transferred per hour. It is widely used in the United States for heating and cooling system ratings. One BTU/hr equals 0.29307 watts, so a 10,000 BTU/hr air conditioner is roughly 2,931 watts.

How do I convert kilowatts to horsepower?

To convert kilowatts to mechanical horsepower, multiply by 1.341022. Alternatively, use this converter: enter your value in kW and the hp field will update automatically. For example, 10 kW equals 13.41 hp.

Power Converter

This power converter lets you switch between six common power units in one step: watts (W), kilowatts (kW), megawatts (MW), mechanical horsepower (hp), BTU per hour (BTU/hr), and calories per second (cal/s). Power is the rate at which energy is transferred or work is done, and the same power level can look very different depending on the unit: one mechanical horsepower is 745.70 watts, 0.7457 kW, and 2,544.43 BTU/hr all at once. The watt is the SI unit of power and serves as this converter's internal reference: you pick any unit, enter a value, and the converter multiplies it by a fixed factor to get watts, then divides by each output factor to show all five remaining units simultaneously. Watts and kilowatts are used for electrical appliances, generators, and motors. Megawatts describe large power stations and industrial machinery. Horsepower is the standard rating unit for vehicle engines and legacy machinery in many markets. BTU per hour is common in heating, ventilation, and air conditioning in the United States. Calories per second appear in thermodynamics and laboratory contexts. You provide one value in any unit and receive all the equivalents instantly. The tool is useful for engineers comparing specifications, students working through thermodynamics problems, mechanics evaluating engine outputs, and building services professionals sizing HVAC equipment. All conversion factors are exact international definitions.

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From unit

Value to convert

745.6999

watts (W)

kW0.7457

MW0.000746

hp1.0000

BTU/hr2544.4336

cal/s178.1073

How it works

Each power unit has a fixed conversion factor to watts. The converter multiplies your input by that factor to get watts, then divides by each output factor to show all results at once. The factors used are: 1 kW = 1,000 W; 1 MW = 1,000,000 W; 1 hp (mechanical) = 745.69987 W; 1 BTU/hr = 0.29307107 W; 1 cal/s = 4.184 W. Because all factors are fixed constants, the conversion introduces no approximation beyond standard floating-point arithmetic.

Worked example

Starting from 1 hp: 1 times 745.70 gives 745.70 W and 0.7457 kW. Dividing 745.70 by 0.29307 gives 2,544.43 BTU/hr. Dividing by 4.184 gives 178.11 cal/s. These match the default values pre-filled in the converter above, so you can verify each output without changing anything.

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