Engine Horsepower Calculator (from ET or Trap Speed)
Estimate horsepower from a car's weight and quarter-mile results.
Power from a quarter-mile run
Drag racers estimate power from how fast a car covers a quarter mile. Trap speed (the speed at the end) is a better guide to power than elapsed time, because it is less affected by how well the car launches.
Example
On the first tab (from elapsed time) with the starting values shown (Weight with driver 3200 lb; Quarter-mile time 13.5 seconds), Estimated horsepower at the wheels comes out as 257. Other results include in kilowatts: 192.
These are rule-of-thumb formulas that assume a typical car and conditions. Tyres, traction, altitude, gearing and weather change the real result, so treat the answer as a rough estimate. Only race in legal, safe settings.
Frequently asked questions
Which is more accurate, ET or trap speed?
Trap speed, because launch skill and traction affect ET far more.
Is this crank or wheel horsepower?
It is closer to wheel power, since it uses the whole car's performance, so engine power is higher.
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