Power-to-Weight Ratio

kW per tonne is power in kW divided by mass in tonnes (1 000 kg); W/kg is the same number. hp per tonne uses mechanical horsepower, 1 hp = 745.7 W; PS (metric horsepower, the figure in many European brochures) is 735.5 W, about 1.4 % smaller, so a 100 PS engine is 98.6 hp. lb/hp is the inverse quoted in North America: mass in pounds (1 lb = 0.45359237 kg) divided by horsepower — smaller is faster. Torque-to-weight divides torque by mass in tonnes.

Manufacturers quote kerb mass (fuel, fluids, sometimes a 75 kg driver — conventions differ by market). Add the driver, passengers, luggage and fuel you actually carry; the page adds the payload to both vehicles in a comparison so the ratio is fair. The comparison reports the second vehicle’s figures and how many times the first one’s ratio it is.

Power is the figure you enter — a crank rating loses 10–20 % to the wheels through the drivetrain, and a dyno’s wheel figure already excludes that. Gearing, traction, aerodynamics, the torque curve and where peak power sits decide acceleration; the ratio is a first comparison, not a prediction. No vehicle data is embedded. Nothing leaves the browser; the same four anonymous usage counts as the rest of the site apply.