1/4 Mile Calculator (ET & MPH)

What is a Quarter Mile Calculator?

A quarter mile calculator estimates how quickly a vehicle will cover 1,320 feet (its elapsed time, or ET) and how fast it will be going at the finish line (its trap speed). It does this from two numbers: weight and horsepower, the two things that matter most in straight-line racing.

How it helps

• Quickly estimate performance without going to the track.
• Test the effect of modifications, such as losing weight or adding horsepower.
• Set realistic goals and compare potential upgrades before you spend money.

The formulas we use

ET is calculated with the Roger Huntington formula: ET = 5.825 × (Weight ÷ HP)^(1/3). Trap speed is MPH = 234 × (HP ÷ Weight)^(1/3). Use wheel horsepower and total race weight. The estimated 1/8 mile ET shown with the results is simply the quarter-mile ET times 0.625.

Some builders prefer the Hale constant of 6.290, which gives slower, more conservative times for the same car. This calculator uses 5.825.

Important disclaimer

The calculator gives a close estimate, but many real-world factors influence actual performance, including track conditions, weather, driver skill, traction, gearing and overall vehicle setup. Treat the results as a starting point, not a guarantee.