What is a horsepower? | Know it All with Jason Cammisa | Ep. 06 - Hagerty Media

Many cars come with two different horsepower ratings, and that’s because there are two measures of horsepower: Imperial Horsepower (hp or bhp) and Metric Horsepower (PS, CV, PK, etc.)

Power is a measure of how quickly work can be done, and horsepower is no different. Imperial (US/SAE) horsepower is defined as 550 ft-lbf/s, where Metric (European/DIN) horsepower is defined as 75 kgf-m/s.

They’re similar, but it turns out European horses are only 0.986 times as strong as American ones.

Of course, horsepower is an outdated unit, replaced by watts. 1 hp = 745.7 watts; 1 PS = 735.5 watt – and of course all electric motors are already rated in thousands of watts, or kW.

But that’s far less sexy, isn’t it?

Watts may move a car, but horsepower sells it.