Quarter Mile Calculator
Enter horsepower and vehicle weight (with driver). Get a ballpark 1/4-mile ET and trap speed from classic power-to-weight approximations used for street and strip what-ifs.
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Measurements convert when you switch units
Result
The formula
Empirical street-strip formulas relate elapsed time and trap speed to the cube root of weight over power. We use widely cited constants: ET ≈ 5.825 × (lb/hp)^(1/3) and trap ≈ 234 × (hp/lb)^(1/3). Real timeslips also need traction, launch, gearing, and weather.
Worked example
- 350 hp, 3,200 lb (with driver)
- W/P = 3200 ÷ 350 ≈ 9.143 · (W/P)^(1/3) ≈ 2.091
- ET ≈ 5.825 × 2.091 ≈ 12.18 s · trap ≈ 234 × (350/3200)^(1/3) ≈ 112 mph
Result: ≈ 12.2 s @ 112 mph (estimate)
How the quarter-mile estimate works
These are correlation formulas from historical power-to-weight trends — not a physics simulation of your launch.
Weight and power basis
Use weight as raced (fuel, driver, spoiler) and horsepower consistent with how the constants were popularized — typically crank or SAE-style peak figures. Mixing wheel hp with brochure curb weight skews results.
Why cube roots
Acceleration capability scales with power/weight; integrating idealized motion yields times that track the cube root of weight/power for similarly set-up cars.
What we do not model
No 60-foot time, tire compound, boost lag, altitude density, shift time, aero drag, or AWD hookup. A sticky prep track can beat this estimate; poor traction will miss it badly.
Interesting facts
1/4 mile = 402.336 m
The NHRA quarter-mile is 1,320 feet (402.336 m). Many countries now run the eighth-mile; this tool is the classic full quarter.
Trap speed vs ET
Trap speed reflects power through the traps more than launch. A poor 60-foot can ruin ET while trap speed still looks strong.
Density altitude
Hot, high, humid air cuts power. Racers correct timeslips to standard conditions — this calculator assumes a generic sea-level-ish street estimate.
Power adders
Nitrous, boost, and sticky radials move you off the “average street car” curve these constants imply.
Frequently asked questions
Often within roughly a half-second for average street cars with decent traction — sometimes worse. Treat it as a what-if, not a prediction you bet on.
Yes for strip estimates. Add driver and typical fuel; curb weight alone is optimistic.
Pick one standard and stick to it. These classic constants are usually discussed with engine-rated horsepower, not hub dyno numbers.
This version solves ET and trap from power and weight. Use timed slips plus weather correction for serious tuning.
Different distance, different correlations. This tool is quarter-mile only.
References
- NHRA — quarter-mile racing context Sanctioning body for drag racing distances and competition formats.
- Vehicle power and performance estimation literature Engineering context for relating power, mass, and acceleration performance.