Free Horsepower to Weight calculator with clear step-by-step results.
Power-to-weight is the ratio that actually predicts acceleration, and it should be measured at the wheels with the car loaded as you drive it. Drivetrain losses of 12-18% are typical, and adding occupant weight to kerb weight moves the figure more than most people expect on a light car.
Power at the wheels
Wheel hp = crank hp x (1 - drivetrain loss)
Power to weight
hp per tonne = wheel hp / total weight kg x 1000
Around 100 hp per tonne is brisk, 200 is genuinely quick and 400 or more is supercar territory. Traction and gearing set the limit long before power does at the top end.
Yes. A transverse front-wheel-drive layout typically loses 10-13%, a longitudinal rear-drive 14-17% and all-wheel drive 18-22% because more gearsets are in the path.