Horsepower Explained

Origin of the Unit

James Watt defined horsepower in the 18th century to compare steam engines to the work a horse could do. He settled on about 33,000 foot-pounds per minute, which works out to about 745.7 watts — so one mechanical horsepower is roughly 0.746 kW.

Modern Use

Car engines are still rated in horsepower, though EVs increasingly use kilowatts. A 200 hp engine produces about 149 kW. The two units convert with a fixed factor.

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