About the Horsepower Calculator
Horsepower is the rate of doing work. For a rotating shaft it comes straight from torque and speed, because power is torque times angular velocity. This calculator converts between torque/RPM, watts and the classic weight-and-trap-speed estimate used at the drag strip.
Also known as: hp calculator, torque to hp, watts to horsepower, bhp calculator, engine power calculator.
How to use this calculator
- Enter calculate from and the other fields.
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Review the breakdown shown under the main result.
- Use Copy result or Share to save the answer or send a link with your inputs.
Formula
P (W) = τ × 2π × RPM / 60 · 1 hp = 745.7 W
Worked example
Using the values pre-filled in the calculator above:
- Calculate from: Torque and RPM
- Torque = 300 N·m
- Engine speed = 5,000 RPM
the calculator returns:
- Horsepower (mechanical): 210.65 hp
- Metric horsepower (PS): 213.57 PS
- Kilowatts: 157.08
- Watts: 157,080