Formula
From ET: HP = Weight × (6.290 ÷ ET)³
Trap speed is generally a more accurate indicator of horsepower than ET, because ET is heavily dependent on launch traction (60-foot times), whereas trap speed is purely an indicator of the power applied across the run.
Worked Example
This calculator provides estimates based on standard mathematical formulas. Real-world results will vary based on mechanical condition, environmental factors, and other variables.
Frequently Asked Questions
Trap speed is much better. A bad launch will ruin ET but won't reduce trap speed much, meaning trap speed provides a more consistent HP calculation.
ET-based estimates are typically within 5–10% for a well-prepared car with good traction. Poor launches, wheelspin, or a heavy track surface make the real horsepower higher than the estimate suggests.
Always use race weight: the car as it runs down the track, including fuel and driver. Leaving the driver out understates weight and underestimates horsepower.
Trap speed reflects sustained power output, while ET is heavily affected by the launch and 60-foot time. Two cars with the same ET but different traction can have quite different horsepower.
Yes. The formula depends only on weight and elapsed time, so it works for any vehicle, though very heavy or aerodynamically unusual vehicles will show more error.
The 60-foot time measures launch quality. A poor 60-foot adds to ET without reflecting engine power, so a car that launches badly will look down on horsepower in an ET-based estimate.