Wheel Horsepower Calculator (Drivetrain Loss)
Choose the direction and enter the horsepower and drivetrain loss.
Your numbers
%
Often quoted as 10% to 15% for manual front- or rear-wheel drive and more for automatics and AWD
Your results
Wheel horsepower
Wheel horsepower
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Crank horsepower
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Lost in the drivetrain (hp)
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Wheel power (kW)
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Wheel Horsepower Calculator (Drivetrain Loss) by TheCalcTools
How the Wheel Horsepower Calculator (Drivetrain Loss) works
Manufacturers quote engine (crank) horsepower; chassis dynamometers measure power at the wheels, after losses in the gearbox, driveshafts and differential.
The loss is usually modelled as a percentage. Real losses vary with the dyno, gearbox and tyres, so treat the conversion as an estimate.
The formula
Wheel hp = crank hp × (1 − loss)
Worked example
Using the default values shown in the calculator:
| Convert | Crank hp to wheel hp |
|---|---|
| Horsepower | 300 |
| Drivetrain loss | 15 % |
- 300 crank hp with 15% loss is about 255.0 hp at the wheels.
Result:
| Wheel horsepower | 255.0 |
|---|---|
| Crank horsepower | 300.0 |
| Lost in the drivetrain (hp) | 45.0 |
| Wheel power (kW) | 190.2 |
Frequently asked questions
Why does my car make less on the dyno than advertised?
The dyno measures at the wheels; drivetrain friction takes part of the engine’s output.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.