Power-to-Weight Ratio Calculator

Power-to-weight ratio describes how much power a car has for every unit of mass it has to move. A lighter car with the same power will have a higher ratio and generally feel keener. Enter a power figure (in BHP, kW or PS) and a weight (in kg, metric tonnes or lb); the calculator converts both to a common base and divides power by weight in tonnes.

Worked example: 300 BHP at 1,500 kg. Convert the weight: 1,500 kg ÷ 1,000 = 1.5 tonnes. Then 300 ÷ 1.5 = 200 BHP per tonne. In kW, 300 BHP × 0.7456998715822702 = 223.71 kW, and 223.71 ÷ 1.5 ≈ 149.1 kW per tonne.

Tick “Compare with a second car” to enter a second vehicle. Both cars should use comparable power and weight measurements — for instance, both quoted at the engine, or both at the wheels — otherwise the comparison will be misleading. You can give each car an optional name to keep track of which is which.

A higher power-to-weight ratio usually points to stronger acceleration potential, but it is not a performance prediction on its own. Gearing, traction, aerodynamics, torque delivery and driver all matter. Use this figure as one signal among many, not a definitive ranking.