Calculators
Engine Horsepower Calculator
Estimate horsepower from the quarter mile.
FreeNo sign-upWorks in your browser
Enter details
Result
Estimated horsepower
250 hp
From trap speed & weight
About the Engine Horsepower Calculator
Estimate an engine's power from track data. Enter the vehicle's weight and its quarter-mile trap speed and the calculator estimates horsepower using the well-known Fox formula: hp = weight × (speed ÷ 234)³. It's a fun, surprisingly accurate way to gauge real-world power.
How to use the Engine Horsepower Calculator
- 1Enter your vehicle weight and quarter-mile trap speed.
- 2Read the result instantly — it recalculates as you type.
- 3Adjust the numbers to model different scenarios.
Frequently asked questions
How accurate is the trap-speed method?
It's a good estimate for stock-ish cars — the Fox formula ties trap speed and weight to power. Aerodynamics and drivetrain loss add variance.
What is trap speed?
Your speed as you cross the quarter-mile finish line. It reflects power-to-weight better than elapsed time alone.