Last updated October 10, 2026 · Report an error
Torque and horsepower are related but different measurements of an engine's output — torque is rotational force, horsepower is the rate of doing work — and the two are only comparable at a specific RPM. This tool converts between them using the standard SAE formula, solving for either value given the other plus RPM.
How it works
HP = Torque(lb-ft) × RPM / 5252, where 5252 is the fixed constant (derived from 33,000 ft-lb/min per horsepower and 2π radians per revolution) at which the torque and horsepower curves always cross on a dyno chart. The reverse direction rearranges this to Torque = HP × 5252 / RPM.
- Enter what are you solving for?.
- Enter torque (lb-ft) — for Horsepower calc.
- Enter horsepower — for Torque calc.
- Enter engine speed (RPM).
- Click Calculate to see your results.
Examples
A performance engine
300 lb-ft of torque at 5500 RPM produces approximately 314 horsepower.
Who should use it
- Estimating an engine's horsepower from a dyno torque reading.
- Figuring out how much torque a motor needs to produce a target horsepower at a given RPM.
Industry applications
- Automotive and motorsports engineering
- Industrial motors and machinery
- Mechanical engineering education
Advantages
- Solves in both directions (horsepower from torque, or torque from horsepower).
- Uses the standard, universally-referenced SAE formula.
Limitations
- Requires knowing the RPM — torque and horsepower alone can't be converted without it.
Common mistakes to avoid
- Comparing two engines' torque figures without accounting for the RPM they were measured at — torque alone doesn't determine horsepower without knowing the RPM.
Best practices
- When comparing engines or motors, compare horsepower (which already accounts for RPM) rather than torque alone if you care about overall power output.
Tips
- Remember the constant 5252 is fixed regardless of engine type — it comes from the definition of a horsepower itself, not from any property of the specific engine.