Quarter Mile Calculator

The calculator uses the classic ET and trap speed formulas derived from drag racing physics. It takes your vehicle weight and wheel horsepower and applies the relationship ET = 6.290 × (Weight/HP)^0.3333 and Trap Speed = 234 × (HP/Weight)^0.3333. These are empirical formulas developed and validated over decades of drag racing data.

The most accurate results come from wheel horsepower (WHP), which is what actually propels the car. Flywheel HP is measured at the engine before drivetrain losses. If you only have flywheel HP, the calculator automatically applies a drivetrain loss factor — roughly 15% for RWD, 18% for FWD, and 12% for AWD — to estimate WHP.

Enter the total weight of the car as it will sit on the starting line — including the driver, fuel, and any passengers or ballast. This 'race weight' is what actually determines performance. Many people mistakenly use curb weight from the manufacturer, which can be significantly different.

These are theoretical estimates based on statistical formulas and assume good traction, a competent driver, and stock-like conditions. Real-world results can vary significantly based on altitude, temperature, track prep, tires, gearing, driver skill, and launch technique. Treat the output as a benchmark, not a guarantee.

A typical stock street car runs in the 14–16 second range. Performance cars often run 11–13 seconds. Purpose-built drag cars can dip below 10 seconds, while top-fuel dragsters run in the 3-second range. A 12-second quarter mile is generally considered a solid milestone for a modified street car.

Trap speed is the vehicle's speed measured at the finish line (the 'traps'). It is one of the most reliable indicators of actual horsepower, since it reflects how much energy the car has built up over the entire run. Many racers consider trap speed more honest than ET, which can be heavily influenced by launch technique.

Many local drag strips run 1/8 mile (660 feet) rather than the full 1/4 mile. The calculator estimates your 1/8 mile ET and speed so you can compare times at these tracks. The 1/8 mile ET is approximately 64% of the quarter mile ET, and the 1/8 mile speed is roughly 80% of the quarter mile trap speed.

Different drivetrain layouts have different mechanical losses between the engine and the driven wheels. RWD cars typically lose around 15% of flywheel power, FWD cars lose about 18% due to the additional complexity of the transaxle and CV joints, and AWD systems lose roughly 12–15% but distribute power more efficiently for launch traction.