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How Much Horsepower Does a Many people wonder exactly how much horsepower a horse has. You might expect the answer to be “one.” Horses are, after all, the animals we use as a baseline measurement for engine power, so it would stand to reason that it’s a 1:1 ratio.

However, the concept of horsepower is more complicated than it appears. Take a closer look at the history of the horsepower measurement to understand how much horsepower a horse actually has.

The Invention of the Term “Horsepower”

Late 18th-century Scottish engineer James Watt needed a way to explain the power output of his revolutionary steam engine in a way that the people of his time would understand. Since most people understood the capabilities of horses, they made for a natural comparison.

Now, despite the implications of the term “horsepower,” actual horses can put out up to 15 horsepower. But crucially, Watt’s measurement wasn’t calculating peak power; instead, it calculated sustained power.

Watt averaged the amount of output a horse could produce in a workday. He concluded that this number represented the amount of work a horse required to pull 150 pounds from a hole 220 feet deep. Interestingly, the “watt” unit of measurement was named after James Watt. One watt is equal to 1/746 horsepower.

Human Horsepower

Horses can produce plenty of horsepower, but surprisingly, so can humans. Top cyclists, such as you’d find at the Tour de France, can produce around 1 horsepower for about 1 minute. Incredibly, Usain Bolt managed 3.5 horsepower during his world-record 100-meter dash sprints.

Alternatives to Horsepower

There are also alternatives to measuring horsepower that you can use.

Kilowatt

The kilowatt is another common form of measurement, also named after the man who invented the concept of horsepower. It’s the world standard for electric motors and measures energy transfer over time.

To calculate kilowatts, take the peak torque — Newton-Meters, not pound-feet, since this is metric — multiply that figure by engine RPM, and divide by 9,565.

PS

This is actually short for the German word “pferdestärke,” which just means “horsepower.” Rather than use James Watts’ Imperial system measurements, PS or metric horsepower measures the power required to lift 75 kilograms one meter per second.

Brake Horsepower (BHP)

Brake horsepower (BHP) isn’t really a different measurement from horsepower. Instead, it’s a different way of testing a vehicle to arrive at its engine’s “true” horsepower.

U.S. measurements are calculated with some parasitic parts removed from the powertrain, which yields a higher number than the European test that keeps such parts in place. Brake horsepower is looking for the actual, usable power of the engine.

Will Horsepower Ever Go Away?

Europe already prefers measuring engine power in kilowatts, and since EV battery capacity is measured in kilowatt-hours (kWh), it’s possible that the term “horsepower” will disappear from our lexicon someday. For now, it remains a popular unit you’ll encounter across a wide variety of applications.

Summary: The term “horsepower” may seem to indicate that horses put out one horsepower. But horsepower is a more complicated measurement than you might expect.

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