Formula
MPH = 234 × (HP ÷ Weight)^(1/3)
These formulas provide estimates for optimal conditions: an excellent launch on a prepped track with drag radials or slicks. Real-world street tires will result in slower ETs.
Worked Example
This calculator provides estimates based on standard mathematical formulas. Real-world results will vary based on mechanical condition, environmental factors, and other variables.
Frequently Asked Questions
The formula assumes perfect traction, gearing, and driver skill. Wheelspin off the line will drastically hurt ET without changing trap speed much.
Yes. Hotter, more humid air or higher elevation increases density altitude (DA), meaning less oxygen for the engine and less horsepower.
Predictions are typically within a few tenths for a car with average traction and gearing. Track conditions, tires, and launch technique cause most of the variation.
ET is the time to cover the quarter mile; trap speed is how fast you're going at the finish line. Trap speed correlates more closely with horsepower, while ET also depends on launch and traction.
Both matter through power-to-weight ratio. Reducing weight and adding power both lower ET, but traction often limits how much of that power reaches the track.