🔌 Power Converter

Convert a power value between watts, kilowatts, mechanical horsepower and BTU per hour.

Value

From Unit

Watts are the base unit here

A watt is one joule per second. Everything is converted into watts and back out again with these factors:

1 kW      = 1000 W
1 hp      = 745.6998715824 W   (mechanical / imperial hp)
1 BTU/h   = 0.29307107 W
1 kW      = 1.34102 hp         = 3412.14 BTU/h

So a 150 hp engine is 150 × 745.7 = 111,855 W, or 111.9 kW. A 2,000 W kettle is 2.68 hp, which is a fair description of how fast it heats water.

Ratings you will meet

Equipment	Watts	hp	BTU/h
LED bulb	9	0.012	30.7
Kettle	2,000	2.68	6,824
1 ton of air conditioning	3,517	4.72	12,000
Family car, 150 hp	111,855	150	381,665
Wind turbine, 3 MW	3,000,000	4,023	10,236,420

Air conditioners and heat pumps are sold in BTU per hour in the United States and in kilowatts almost everywhere else. Divide BTU/h by 3,412 to get kW, or multiply kW by 3,412 to go the other way.

This tool uses mechanical horsepower, 745.7 W. European car makers quote metric horsepower, written PS or CV, which is 735.49875 W - 1.4% smaller. A car listed at 200 PS is 197 hp, so a spec sheet that disagrees with a review by a couple of horsepower is usually this, not a different engine.

Frequently asked questions

How many watts is 1 horsepower?

745.7 watts for mechanical horsepower, the figure this converter uses. Metric horsepower, badged PS or CV on European cars, is 735.5 watts instead.

How many horsepower is 100 kW?

134.1 hp, or 136.0 PS in metric horsepower. The quick version is to multiply kilowatts by four thirds, which puts you within half a percent.

How many BTU per hour is 1 kW?

3,412 BTU per hour. That is why a 12,000 BTU/h air conditioner, the old one ton rating, is sold as a 3.5 kW unit outside the United States.