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What does HP, PS and KW mean?

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Updated 6 Nov 2019Michael Jacobson
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Initially speaking, HP might be a brown sauce or a well-known computer company; PS could refer to a note at the end of a letter or a Sony PlayStation; and KW might be the country code for Kuwait, the Kamera-Werkstatten photographic company in Germany or a scientific designation for the self-ionisation of water.

Of course, none of these have the slightest bearing on this article, but the following do – HP for horsepower, PS for pferdestarke, and KW for kilowatt – all powerful terms pertaining to the power of your vehicle.

So, what’s the difference between them and why must we go back to an 18th Century Scottish inventor to find out?

Say Watt

James Watt is the man in question, and in 1776 he unveiled his version of the steam engine that would help usher in the Industrial Revolution and change the world.

Mind you, first he had to convince the punters of the virtues of his handiwork, which meant coming up with a readily identifiable term to describe this new form of power and its industrial/mechanical potential.

That term was horsepower, a measurement Watt calculated to be the equivalent of one horse lifting 33,000 pounds (15,000kg approximately) over one foot (30cm approximately) in one minute on the surface of the Earth.

Of course, the equation might have been different had the horse been Winx, and it’s also worth pondering whether today’s G-forces bear any relation to Watt’s gee-gee forces.

What is beyond dispute is the fact that one horsepower (1hp) is the equivalent of 746 watts or 0.746 kilowatts, and the more horsepower in your vehicle, the happier you probably are.

Accordingly, our gratitude goes to James Watt for coming up with a term that is inextricably linked to motoring and has also become a part of everyday language.

PS: now it’s time to move on from HP to PS.

Name of thrones?

It’s not every day you get to use the word pferdestarke in a sentence, right?

And while it sounds like one of the characters from Game of Thrones — the Stark family is a big deal in the ancestral seat of Winterfell — pferdestarke is a German word that translates simply as “horsepower” and reflects the move to impose metric measurement over the mechanical.

You may be aware of other terms derived towards the same purpose, including CV (chevaux vapeur), which is French for horsepower; and DIN metric horsepower.

It’s easy to understand why some people would prefer the convenience of the metric system, although surely the true metric standard of power is the kilowatt.

A kilowatt comprises 1000 watts and the conversion to horsepower requires multiplying by 1.34 – for example, 50kW equates to a shade over 67hp.

While horsepower, watts and kilowatts each represent the expenditure of a certain rate of energy or power, they do tend to occupy their own space.

Just as you are unlikely to describe your new vacuum cleaner as having 1.34 horsepower, you are equally unlikely to extol the 478kW virtues of your brand-spanking new Lamborghini Urus.

Horses for courses

Is there are more familiar term in motoring than horsepower?

We could take a vote, but I reckon the neighs have it.

Still, whether you're hooked on horses, wild about watts or – excuse the spelling – krazy about kilowatts, AutoGuru is the place to visit for information and advice on all things automotive.

In other words, more power to you.

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Written ByMichael Jacobson

Michael Jacobson is an award-winning Queensland-based writer.

His appreciation for motoring began as a young journalist covering racing from Simmons Plains in Tasmania.

Over the years he has interviewed many Australian and international motoring greats.

He has also been driven around Lakeside Raceway at ferocious speed, circumnavigated the Gold Coast Indy circuit at more than 200kmh and managed to squeeze 365,000 kilometres out of a Toyota Starlet.