Power Converter
Enter a power value and its unit to see the equivalent in watts, kilowatts, horsepower, and BTU per hour.
How power conversion works
The watt (W) is the SI unit of power — the rate of energy transfer, equal to one joule per second. Mechanical horsepower is defined as exactly 745.699872 W, a unit that originated from comparing steam engine output to the work rate of a horse.
BTU per hour is a rate of energy transfer commonly used for heating and cooling equipment capacity in the US, equal to about 0.293 W.
Frequently asked questions
How many watts is one horsepower?
1 mechanical horsepower equals exactly 745.699872 watts (approximately 746 W).
Is horsepower the same in every country?
No — this calculator uses mechanical horsepower (745.7 W), but metric horsepower (used in much of Europe) is defined slightly differently, at about 735.5 W.
What's the difference between power and energy?
Power is the rate at which energy is used or transferred (measured in watts); energy is the total amount used over time (measured in joules or watt-hours) — power × time = energy.