Convert Engine Horsepower to Wheel Horsepower
Calculate wheel horsepower from engine horsepower measurements. Account for drivetrain losses in front-wheel, rear-wheel, and all-wheel drive systems.
Wheel Horsepower Calculator
Frequently Asked Questions
What is Wheel Horsepower (WHP)?
Wheel Horsepower (WHP) is the actual power that reaches the wheels after accounting for drivetrain losses. It represents the power available to move the vehicle, as measured at the wheels on a dynamometer. This is different from engine horsepower, which is measured at the engine's flywheel.
How much power is lost through the drivetrain?
Front Wheel Drive (FWD): 10% - Most efficient due to shorter power path.
Rear Wheel Drive (RWD): 15% - Additional loss through driveshaft and differential.
All Wheel Drive (AWD): 25% - Highest loss due to transfer case and multiple differentials.
What is the HP to WHP formula?
The formula is: WHP = HP × (1 - DL)
Where WHP = Wheel Horsepower, HP = Engine Horsepower, and DL = Drivetrain Loss (as decimal).
For example: 300 HP with RWD = 300 × (1 - 0.15) = 255.00 WHP
When should I use this calculator?
Use this calculator when you know your engine's horsepower rating and want to estimate the actual power delivered to the wheels. This is useful for performance estimates, understanding real-world power output, or comparing vehicles with different drivetrain configurations.
Why is WHP important for performance?
WHP is a more accurate measure of a vehicle's actual performance potential because it represents the power that actually reaches the wheels. Two cars with the same engine horsepower but different drivetrains will have different wheel horsepower and therefore different acceleration capabilities.
How accurate are these calculations?
These calculations use industry-standard drivetrain loss percentages and provide good estimates. Actual losses can vary based on vehicle condition, drivetrain design, temperature, and other factors. For precise measurements, professional dynamometer testing is recommended.