WHP to HP Calculator
Convert wheel horsepower to engine (crank) horsepower using drivetrain loss.
A chassis dyno measures wheel horsepower (WHP), but engine specs are quoted in crank horsepower. This calculator converts your dyno's wheel figure back to crank power by adding the drivetrain loss.
WHP to HP Formula
How to Use This Calculator
- Enter wheel horsepower from your dyno sheet.
- Set drivetrain loss % for your layout.
- Read estimated crank horsepower.
Worked Example
For the opposite direction, see the wheel horsepower calculator, and read wheel HP vs crank HP for the full explanation.
Frequently Asked Questions
Divide wheel horsepower by (1 minus the drivetrain loss fraction). For 15% loss, divide by 0.85.
Roughly 10% for FWD, 15% for RWD, and 20–25% for AWD. Automatics tend to lose a little more than manuals.
The drivetrain absorbs power through friction before it reaches the wheels, so the crank figure is always higher than what the dyno reads at the wheels.
It's an approximation. Real losses vary with transmission type, temperature, and even tire and roller friction on the dyno.
Crank (flywheel) horsepower, measured on an engine dyno before drivetrain losses.