Engine Horsepower Calculator
Estimate engine horsepower from quarter mile time and vehicle weight using the ET-based horsepower formula.
Estimated Horsepower
Estimating horsepower from quarter mile performance uses a well-known empirical formula derived from drag racing data.
Formula (Roger Huntington method):
HP = Weight / (ET / 5.825)^3
Where:
- HP = Estimated horsepower at the wheels
- Weight = Total vehicle weight in pounds (including driver)
- ET = Quarter mile elapsed time in seconds
Notes:
- This estimates wheel horsepower (WHP), not crank horsepower
- Drivetrain loss is typically 15% for FWD/RWD and 20% for AWD
- For crank HP, divide WHP by 0.85 (RWD) or 0.80 (AWD)
- The formula works best for ETs between 10–18 seconds
- Add ~150–200 lbs to curb weight to account for the driver