Science
Horsepower Calculator
Horsepower from torque + RPM, kW conversion, or estimated from vehicle weight and quarter-mile time.
Inputs
Horsepower Calculator
Result
Horsepower
285.61 hp
- Kilowatts
- 212.98 kW
- Metric horsepower (PS)
- 289.57 PS
How it's calculated
HP = Torque × RPM / 5252 | 1 hp = 0.7457 kW | HP ≈ weight(lbs) / (ET / 5.825)³
Common questions
Why 5252?
It's the RPM where the horsepower and torque curves cross when torque is in lb-ft. The constant comes from 33 000 ft·lb/min per hp divided by 2π.
How accurate is the quarter-mile HP estimate?
The Hale/Fox formula assumes near-perfect launch and gearing. Real-world results vary by traction, drivetrain losses, and driver skill, but it's a solid ballpark for stock vehicles.
Related calculators
Science
Ohm's Law Calculator
Solve for voltage, current, or resistance from the other two — plus the resulting power draw.
Science
Speed / Velocity Calculator
Solve for average speed, distance, or time using the classic v = d / t relationship.
Science
Density Calculator
Solve for density, mass, or volume from the other two using ρ = m / V.
Science
Force Calculator
Newton's second law solver — find force, mass, or acceleration from the other two.