How to use this calculator
- Enter race weight. Include driver, fuel and ballast.
- Enter engine power. Use crank power or set efficiency to 100 percent for wheel power.
- Set drivetrain efficiency. Estimate the power delivered to the tires.
- Read ET and trap. Treat the result as a screening estimate.
How it works
The page converts crank power to wheel power, then applies common empirical weight-to-power quarter-mile equations: ET = 5.825 x (weight / wheel hp)^(1/3).
For drivetrain checks, use wheel torque, RPM drop and aero drag horsepower.
Worked example
Verified against the live calculator
A 3,500 lb car with 450 hp at the crank and 85% drivetrain efficiency is roughly 383 whp, estimating near 12.2 seconds and 112 mph before traction and gearing effects.
Frequently asked questions
How does the quarter-mile calculator estimate ET?
It uses a common empirical weight-to-wheel-power formula: ET is proportional to the cube root of weight divided by wheel horsepower.
Is this a drag simulation?
No. It is a quick estimate from weight and power, not a full traction, aero, shift or gearing model.
Should I enter crank horsepower or wheel horsepower?
Enter crank power and drivetrain efficiency. Set efficiency to 100 percent if you already have wheel power.
Why can real cars differ from the estimate?
Launch grip, gearing, shift time, aero drag, weather, tire growth and driver inputs can all move real results.
Method & assumptions
- Uses empirical drag-racing weight-to-power formulas.
- Does not model tire grip, gearing, shift time, aero drag, track prep, altitude or weather.