Power-to-Weight Ratio Calculator (kg/HP)

Power-to-weight ratio: the most honest performance metric

The ratio is just kg/HP = weight / power, and the inverse is HP/ton = 1000 / (kg/HP). Take 1,200 kg with 150 HP: that works out to 8 kg/HP, about what you'd expect from a hot hatch. A budget compact sits around 12 kg/HP. Sports cars run 4-6, supercars 2-3, an F1 car hovers near 1, and sport bikes drop below 1.5. The Bugatti Chiron manages roughly 0.9 kg/HP. A lower number means quicker acceleration, and the empirical data backs this up: the ratio tracks 0-100 km/h times far more reliably than raw horsepower does.

Applications

Compare acceleration between cars at a glance, make sense of MotoGP and F1 specs, sort out drag racing classes, or work out whether a tuning project should shed weight or add power. Quite often, cutting weight buys you more seconds per dollar than chasing horsepower.

FAQ

Does the ratio predict 0-100 km/h exactly? No. Traction, gearbox, aero and the shape of the torque curve all play a part. That said, among cars with similar drivetrains it ranks them in the right order.

Why does the Chiron beat lighter supercars? At 0.9 kg/HP and with all-wheel drive, it actually puts its power down. A lighter rival with a worse ratio bogs down off the line.

Should I count the driver's weight? On bikes and karts, definitely. The rider's mass swings the ratio by 10-20%. In a car it matters less, though it still shows up when you're comparing track day times.