How it's calculated
power-to-weight = power ÷ weight
power and weight are normalised to consistent units (W, hp, kW; kg, lb, t). Outputs include hp/lb, W/kg, kW/kg and hp/tonne. A higher ratio means quicker acceleration.
Common questions
Why does power-to-weight matter more than horsepower alone?
Acceleration depends on power relative to mass, so a light car can out-accelerate a heavier one with the same horsepower.
What units do cyclists use?
Cyclists usually track watts per kilogram, since it predicts climbing performance well.