Quarter Mile ET Calculator

The History of the Quarter Mile The quarter mile (1,320 feet / 402 meters) became the standard drag racing distance in the 1950s, chosen partly because early drag strips were improvised on airport runways and taxiways that were approximately a quarter mile long. The National Hot Rod Association (NHRA) was founded in 1951 by Wally Parks and standardized the quarter mile as the competitive distance for professional drag racing.

The Performance Formulas Both formulas here come from Roger Huntington, who fitted them in the 1950s against published quarter-mile times, and they have outlasted every car they were derived from:

ET = 5.825 × (Weight ÷ Horsepower)^(1/3) Trap speed = 234 × (Horsepower ÷ Weight)^(1/3)

The two constants are a matched pair, so mixing one of them with a figure from somewhere else gives you a car that cannot exist. This page previously ran the ET side at 6.290, which put it 8% out of step with the engine horsepower calculator, the page that works the same formula backwards. A 300 hp car went into one page and came out of the other as a 239 hp car.

Enter crank horsepower, not wheel horsepower. Huntington fitted against flywheel figures, which is what a manufacturer quotes. If all you have is a chassis dyno number, add about 15% back for a manual rear-drive car and more for an automatic or all-wheel-drive one.

These assume a well-driven car on a prepared strip with good traction, which is what the two penalty dropdowns below are for. Real-world results still vary with driver skill, launch technique, transmission type, gearing and aerodynamic drag. In practice the trap speed prediction is the more trustworthy half: a bad launch costs you several tenths of ET but barely touches the speed at the far end.

Power-to-Weight Ratio Is Everything The single most important factor in quarter mile performance is the power-to-weight ratio (hp divided by total vehicle weight in pounds). A lightweight car with modest power can beat a heavy car with much more power.
A stock Miata at 130hp and 2,400 lbs has a ratio of 0.054, comparable to many muscle cars of the 1960s. A Tesla Model S Plaid makes 1,020hp and weighs 4,766 lbs, a ratio of 0.214, and runs a claimed 9.23-second quarter.

Note that the Plaid beats what this formula predicts for it, and by a good margin. An electric car makes full torque from zero and puts it through all four wheels, so it launches in a way no combustion car fitted in the 1950s ever did. Huntington’s model sees only mass and power.

Traction and Drivetrain Losses Front-wheel drive vehicles face an inherent disadvantage: under hard acceleration, weight shifts rearward, away from the driven front wheels. This causes wheelspin and traction loss. Rear-wheel drive vehicles benefit from weight transfer adding grip to the drive wheels. All-wheel drive is fastest off the line because all four tires put power down, though the drivetrain weight penalty is small.

Famous Quarter Mile Times Stock Dodge Challenger SRT Hellcat (717 hp): approximately 11.2 seconds at 126 mph. Stock Chevrolet Corvette Z06 (670 hp): approximately 10.8 seconds. Modified NHRA Top Fuel dragster (11,000 hp+): approximately 3.6 seconds at over 335 mph. The fastest street-legal production cars now run sub-10 seconds, a benchmark that was reserved for dedicated race cars just 20 years ago.

Safety Note Drag racing on public roads is illegal and extremely dangerous. Use a sanctioned drag strip for any performance testing. NHRA-member tracks have safety barriers, medical personnel, and proper surface preparation.