Quarter-Mile ET Predictor

Enter vehicle weight and horsepower to estimate ET and trap speed.

Vehicle weight with driver (lbs)

Wheel horsepower (WHP)

Estimated ET (elapsed time) —

Estimated trap speed —

Weight-to-power ratio —

ET = 5.825 × (weight/HP)^(1/3). Trap speed = 234 × (HP/weight)^(1/3). These are estimates — actual times depend on traction, weather, driver skill, and gearing.

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Quarter-Mile Benchmarks

ET	Trap Speed	Example
16+ sec	< 85 mph	Economy cars
14–16 sec	85–100 mph	Average cars
12–14 sec	100–115 mph	Sports cars
10–12 sec	115–130 mph	Muscle cars / fast sports
8–10 sec	130–160 mph	Supercars / modified
< 8 sec	160+ mph	Top Fuel / Pro Stock

Predicting Quarter-Mile Times

The quarter-mile ET (elapsed time) can be estimated from vehicle weight and horsepower using the formula: ET = 5.825 × (weight/HP)^(1/3). This is known as the Roger Huntington formula.

Trap speed (the speed at the finish line) is estimated as: trap = 234 × (HP/weight)^(1/3). Both formulas assume reasonable traction and a competent launch.

The ET (elapsed time) estimators used here come from empirical formulas developed from drag racing data. The most common: ET = 6.290 × (weight/HP)^(1/3) for an average street car. A 3,500 lb car with 300 wheel HP: ET = 6.290 × (3500/300)^0.333 = 6.290 × 11.67^0.333 = 6.290 × 2.269 ≈ 14.27 seconds.

Trap speed (MPH at finish) relates to ET by: MPH ≈ 234 × (HP/weight)^(1/3). Same car: MPH = 234 × (300/3500)^0.333 = 234 × 0.441 ≈ 103 mph. These are estimates for typical street-prepped vehicles — tire traction, launch technique, aerodynamics, and transmission type all affect actual results significantly.

Weight reduction vs. power addition: reducing weight has the same proportional effect as adding power. Removing 350 lbs (10% of 3,500) provides roughly the same ET improvement as adding 10% more power. For a 14-second car, each 0.1-second improvement requires approximately 1–2% improvement in power-to-weight ratio.

Altitude correction: air density decreases at higher elevation. For every 1,000 feet of altitude, naturally aspirated engines lose approximately 3% power. A car that runs 13.5 seconds at sea level will run approximately 13.9 seconds at 5,000 feet elevation (Denver). Turbocharged engines compensate better — turbo boost maintains charge density more effectively than NA induction.