| Horsepower | ET | Trap Speed |
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How Quarter Mile Times Are Estimated
Decades of drag-strip data show that elapsed time and trap speed track closely with just two numbers: how much power a car makes and how much it weighs. This tool uses the well-known Hale and Huntington equations to turn horsepower and weight into a predicted quarter-mile ET and trap speed.
ET vs Trap Speed
Elapsed time is how long the run takes; trap speed is how fast you are going at the finish line. Trap speed is the better measure of raw power because it is far less sensitive to the launch — a bad start ruins your ET but barely dents your trap speed. That is why estimating horsepower from trap speed is so reliable.
Why Your Real Time May Differ
These equations assume the car can put its power down. Traction, tires, gearing, transmission type, weather, altitude, and the driver all move the result. Street tires and a soft launch push you toward the slower estimate; drag radials and a dialed-in launch push you toward the quicker one.
Improving Your Quarter Mile
Because ET depends on power-to-weight, shedding weight helps almost as much as adding power. Better tires, the right gear ratio, and a clean launch often find more time than bolt-on power alone. Use the power-level table above to see what each step of horsepower is worth.
Frequently Asked Questions
Should I use flywheel or wheel horsepower?
These equations are calibrated to flywheel (crank) horsepower. If you only have a dyno wheel figure, add roughly 12 to 18 percent for a typical drivetrain.
Does weight really matter that much?
Yes. ET and trap speed both scale with power-to-weight, so 100 lb is often worth a tenth or more in the quarter.
Why are two ET numbers shown?
The Hale equation reflects a strong, well-hooked-up run, while the Huntington equation is more conservative. Real-world results usually fall between the two.