Horsepower Calculator
Horsepower Calculator works out Torque and Power from Force (or brake clamp force), Force unit and Lever arm / effective radius. The default figures on this page give power of 21.0647 hp; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
3 steps
- Torque given as 50 Nm = 50 N m
- omega = 2 pi x 3000 / 60 = 314.15927 rad/s.
- P = tau omega = 50 x 314.15927 = 15707.96 W = 15.708 kW = 21.0647 hp.
Its 5 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
3 sources
What the Horsepower Calculator calculates
Converts between torque, rotational speed and power in both SI and imperial units, computes torque from a force on a lever arm, and computes brake torque from clamp force, pad friction and effective rotor radius.
How to use this Horsepower Calculator
Enter Force (or brake clamp force), Force unit, Lever arm / effective radius and Length unit. Torque updates as you type. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Torque, Power and Angular velocity.
The method follows Definition of the moment of a force and of rotational power, NIST Special Publication 811, Guide for the Use of the International System of Units and SAE J866 / brake system fundamentals: braking torque = 2 mu N r_effective for a two-pad caliper.
What you can compare
Change one input at a time to see how it affects Torque, Power and Angular velocity. The inputs you can vary are Force (or brake clamp force), Force unit, Lever arm / effective radius, Length unit, Angle between the force and the lever arm and Torque.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
See something wrong? Report a problem with this calculator
Frequently asked questions
Is there a horsepower calculator?
Converts between torque, rotational speed and power in both SI and imperial units, computes torque from a force on a lever arm, and computes brake torque from clamp force, pad friction and effective rotor radius. On the figures this page opens with — force (or brake clamp force) 100 and lever arm / effective radius 0.5 — the power is 21.0647 hp. Put your own figures in their place and the working updates beside the result.
How do you calculate horsepower?
Converts between torque, rotational speed and power in both SI and imperial units, computes torque from a force on a lever arm, and computes brake torque from clamp force, pad friction and effective rotor radius. Open “How this is worked out” beside the result to see each step for your own figures.
How fast is 4000 horsepower?
It needs Force (or brake clamp force), Force unit, Lever arm / effective radius, Length unit, Angle between the force and the lever arm and Torque. Nothing else is required, and the figures stay in your browser.
How much is 80 horsepower?
On the figures this page opens with — force (or brake clamp force) 100 and lever arm / effective radius 0.5 — the power is 21.0647 hp. No single number fits everyone: change any figure above and the answer updates as you type, with each step of the arithmetic beside it.
What information do I need for the Horsepower Calculator?
You need Force (or brake clamp force), Force unit, Lever arm / effective radius, Length unit, Angle between the force and the lever arm, Torque, Torque unit and Rotational speed. The page opens with default figures that give power of 21.0647 hp, so you can see the scale before entering your own.
What does this Horsepower Calculator show?
It shows Torque, Power, Angular velocity and Rotational speed, with the working and any warnings for your entries.