Engine Horsepower Calculator
Estimate engine horsepower from quarter mile performance
Engine Horsepower Calculator
Use our engine horsepower calculator below to estimate the engine horsepower of a vehicle based on the weight of the vehicle and quarter mile performance. Choose between the Elapsed Time (ET) method or the Trap-Speed method.
Quick Navigation
âąī¸ Elapsed Time (ET) Method
đ ET Method Results
đ Trap-Speed Method
đ Trap-Speed Results
đ Understanding Engine Horsepower
What Is Horsepower?
Horsepower was created by engineer James Watt to measure engine power. One horsepower equals 33,000 foot-pounds per minute or 746 watts.
Horsepower vs Torque
Torque is rotational force, while horsepower is the rate of doing work. High torque provides acceleration, while high horsepower provides top speed.
Safety Precautions
Never measure quarter-mile times on public roads. Use only legal venues like drag strips or private roads during organized events.
Calculation Methods
Elapsed Time (ET) Method
This method uses the vehicle weight and elapsed time to finish a quarter mile (402.3 meters). The formula is: HP = Weight / (ET/5.825)Âŗ
This method is based on the physics of acceleration and provides estimates for peak horsepower when maximum work output is applied from start to finish.
Trap-Speed Method
This method uses vehicle weight and the speed attained at the quarter-mile point. The formula is: HP = Weight à (Speed/234)Âŗ
The speed used should be the trap speed (speed at the finish line), not the average speed throughout the run. This method often provides different results than the ET method.
Note: Both calculation methods provide estimations only. Actual engine dyno testing is required for precise horsepower measurements. Vehicle weight should include driver, passengers, and any significant cargo.