Power-to-weight converter
Convert power-to-weight between hp per tonne, W/kg, kW per tonne and pounds per horsepower.
That's 1.02× as lively as a hot hatchback, while a supercar is 2.8× livelier.
What it means
How lively is that?
Vehicle figures are typical, with the driver or rider left out. Cyclist figures are power held for an hour.
Every unit
Your power-to-weight in every unit
Learn
Three things worth knowing
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1 W/kg is 1.34 hp per tonne
A family car at 55 W/kg is about 74 hp per tonne; a Formula One car is well over 1,000.
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Why cyclists count watts per kilo
Uphill, most of a rider’s effort goes into lifting their own weight, so a light rider with modest power beats a heavy one with more. Four watts per kilo is a strong amateur; six is a professional climber.
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Lower is better in lb/hp
Pounds per horsepower runs the other way: 10 lb/hp is quick, 30 lb/hp is sluggish. Mixing it up with hp per tonne gets every comparison backwards.
Shortcuts
Popular power-to-weight ratio conversions
Background
About power-to-weight
Power decides top speed; power per kilogram decides how quickly you get there, and how fast you climb a hill. It is why a light hatchback can keep up with a heavy saloon.
Cyclists talk in watts per kilo, car magazines in horsepower per tonne, and older US road tests in pounds per horsepower, which is the same idea upside down.