Horsepower Calculator
Calculate engine horsepower using vehicle weight and quarter mile time
How to Use
Calculation Methods
Elapsed Time Method
Uses the vehicle's weight and quarter-mile elapsed time to estimate horsepower.
HP = weight / (elapsed_time / 5.825)³
Trap Speed Method
Uses the vehicle's weight and quarter-mile trap speed to estimate horsepower.
HP = weight × (speed / 234)³
Required Information
- Vehicle Weight:
Total weight including vehicle, driver, passengers, fluids, and any significant cargo. Can be entered in kilograms or pounds.
- Quarter Mile Performance:
Either the elapsed time (in seconds) or the trap speed (in mph) at the end of a quarter mile (402.336 meters) run.
Understanding Results
- Mechanical Horsepower (hp):
Imperial unit of power equal to 550 foot-pounds per second. This is the standard measure used in the US and UK automotive industry.
- Metric Horsepower (PS):
Also known as Pferdestärke, commonly used in European and Japanese markets. 1 PS ≈ 0.986 hp.
- Kilowatts (kW):
SI unit of power used internationally. 1 hp = 0.7457 kW. Preferred in scientific and engineering contexts.
- Foot-Pounds per Second (ft⋅lb/s):
Basic unit of mechanical power in imperial system. 1 hp = 550 ft⋅lb/s.
Important Notes
Results are estimates based on quarter-mile performance and don't account for factors like air resistance, rolling resistance, or drivetrain losses.
For most accurate results, perform measurements on a proper drag strip or race track, not on public roads.
For precise power measurements, consider professional dynamometer testing.