Quarter Mile
Calculator
Explore empirical quarter-mile elapsed-time and trap-speed estimates from race-ready weight and engine horsepower, with visible model coefficients.
Your setup
Your results
CalculatedA comparative empirical estimate. Treat it as a starting point for discussion, not a predicted time slip.
Coefficients are not calibrated to your car. Launch, gearing, traction, aerodynamics, power definition, weather and shift time can dominate.
How the calculation works
Follow the formula and keep the input units consistent at every step.
ET(s) = 5.825 × (W_lb / HP)^(1/3); trap MPH = 234 × (HP / W_lb)^(1/3)- Include driver and fuel in race-ready weight.
- Convert weight to pounds and power to mechanical horsepower.
- Apply the empirical cube-root ET and speed models.
A Worked Example
For 3,200 lb and 400 hp, weight/power = 8. Its cube root is 2, so model ET is 11.65 s and trap speed is 117 MPH.
What Your Result Means
A comparative empirical estimate. Treat it as a starting point for discussion, not a predicted time slip.
Assumptions & Limitations
Coefficients are not calibrated to your car. Launch, gearing, traction, aerodynamics, power definition, weather and shift time can dominate.
Common Mistakes
Do not mix wheel horsepower and engine horsepower or omit driver weight.
Questions about this calculation
Which values should I enter?
Include driver and fuel in race-ready weight. Do not mix wheel horsepower and engine horsepower or omit driver weight.
How should I interpret the result’s precision?
Displayed results are rounded for readability. Intermediate calculations retain floating-point precision; extra displayed decimals do not improve your input accuracy.
Can I use metric units?
Yes. Select Metric above the calculator to convert your inputs. Results always state their units. Tire-size designations keep their conventional mm and inch units.
What are the main limitations?
Coefficients are not calibrated to your car. Launch, gearing, traction, aerodynamics, power definition, weather and shift time can dominate.
Method, sources & relevant guides
Hale coefficient model: ET constant 5.825 and speed constant 234. Lucius documents the formulas and compares them with road-test data. These are empirical relationships, not physical laws or calibrated vehicle predictions.
Jeff Lucius / Stealth 316 — Quarter-mile formulas and original regression analysisMethod documentation updated October 18, 2026. Independent professional review has not been claimed. Read the calculation and review policy.