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1 October 2020

Power converter: bhp, PS and kW

Find out exactly how powerful your car is. Our free tool lets you easily switch between bhp, PS and kW.
Power converter 447571
Martin Pratt

Most cars measure power by the horse, but bhp isn't the only unit manufacturers use to tell us how much oomph there is in the engine.

Pferdestärke, or PS for short, and Kilowatts (kW) are both lesser used units for determining a car's engine power that mostly show up in mainland Europe.

Our tool converts between the three, so you can check how powerful a car is in a pinch.  

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How powerful is my car? 

Carmakers sometimes quote the power outputs of their engines using different units, which can be confusing when you're trying to compare new cars. 

This handy calculator lets you convert quickly and easily between the three main measurements used – bhp, kW and PS.

What is bhp?

Brake horsepower – or bhp – is the most widely used measure of engine power alongside PS (see below), although it's often not clear which unit manufacturers are using in their brochures. 

Unlike ‘horsepower’, which refers to an engine’s total output, brake horsepower only looks at the amount of energy left once other parts such as the gearbox, alternator and water pump have all been powered. It's measured at the road wheels, not at the flywheel.

Powerful engines have a higher bhp figure. For example, an entry-level Toyota iQ has a 68bhp engine, while a supercharged Jaguar XF packs 503bhp.

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PS explained

Although it’s still commonly used by carmakers, PS or Pferdestärke (horse strength in German) was actually replaced by kW as the EU's ‘legal’ measurement of engine power in 1992. 

One PS is about 98.6% of a brake horsepower – the two are virtually interchangeable, and PS is sometimes referred to as 'metric horsepower'.

Measuring power in kilowatts

You may see some carmakers quoting the power of their engines in kilowatts – especially on the continent – but this measurement is used far less frequently than PS or bhp. A kilowatt (kW) of power equates to around 1.34bhp.

So what is torque?

Torque refers to the amount of pulling power an engine delivers when working at different speeds. The more torque an engine has, the more pull (or acceleration) it offers at lower revs.

Torque is nearly always discussed alongside brake horsepower, as it gives clues to how quickly the engine will be able to shift the car’s weight when overtaking or pulling away from traffic lights.

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