Enter the wheel horsepower and select the drivetrain of the car to determine the HP from WHP.

WHP to HP Formula

The following formula is used to calculate the engine horsepower (hp) from wheel horsepower (WHP). 

HP = WHP * 1 / (1 - DL )
  • Where HP is the engine horsepower
  • WHP is the wheel horsepower
  • DL is the drive train loss

To calculate the HP from WHP, multiply the wheel horsepower by 1 divided by the result of 1 minus the drive train loss.

The drive train loss is .10 (10%) for front-wheel drive, .15 for rear-wheel drive, and .25 for all-wheel drive.

Why are HP and WHP different?

HP is typically used to refer to the true engine horsepower output, while WHP is used to describe the wheel horsepower, which is the horsepower that makes it to the wheel after drive-train loss is accounted for.

How to conver WHP to HP?

Example Problem:

The following example problem outlines the steps and information needed to calculate HP from WHP.

First, determine the wheel horsepower. In this case, the wheel horsepower is measured to be 250 HP.

Next, determine the type of drive train. In this example, we are looking at a front-wheel-drive system.

Next, determine the drive-train loss of the system from the type of drive-train. In this case, the DTL is .10.

Finally, calculate the HP from WHP and DL using the formula above:

HP = WHP * 1 / (1 – DL )

HP = 250 * 1 / (1 – .10 )

HP = 277.77 horsepower