Quarter Mile Calculator
Predict your 1/4 mile time and speed from weight and horsepower.
Car + Driver + Fuel
Flywheel Horsepower (BHP)
Elapsed Time (ET)
0 sec
Trap Speed
0 MPH
Quarter Mile Mathematics
Predicting quarter-mile performance is a mix of physics and experience. The calculator uses the **Hale Formula**, widely accepted in the racing community for its accuracy in predicting performance for naturally aspirated vehicles with good traction.
The Formula
ET = 5.825 × (Weight / HP) ^ 1/3MPH = 234 × (HP / Weight) ^ 1/3Accuracy Factors
While horsepower and weight are the biggest factors, they aren't the only ones. Real-world times are affected by:
- Traction: Spinning tires at the launch kills ET.
- Gearing: Optimal gear ratios keep the engine in its power band.
- Aerodynamics: At speeds over 100mph, drag becomes a major factor.
- Driver Skill: Reaction time (doesn't affect ET, but affects win/loss) and shift points matter.
FAQ
How accurate is this calculator?
This calculator uses the Hale formula, which is a standard industry estimation. It assumes good traction and optimal shifting. Real-world results may vary due to tires, driver skill, and weather.
Do I use curb weight or race weight?
Use Race Weight. This includes the car, driver, fuel, and any cargo in the vehicle at the time of the run.
Why does my car run slower than the prediction?
Common factors include wheel spin (traction loss), slow shifting, high altitude (less oxygen for engine), or hot weather.
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