Torque from horsepower and rpm
If you know engine power at a given rpm, this tool gives the torque at that point in both common units.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter power, power unit and engine speed.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Torque (N·m) = power (W) × 60 ÷ (2π × rpm). lb-ft = N·m ÷ 1.3558179. Directly from hp: torque (lb-ft) = hp × 5252 ÷ rpm.
Example
Inputs: Power = 200, Power unit = hp, Engine speed = 5,500 rpm. Result: Torque: 258.9 N·m; Torque in lb-ft: 191 lb-ft.
Limits and caveats
- The torque is at the entered rpm only, not the engine's peak torque.
- Pick the right power unit: European makers often quote metric PS.
Questions about this tool
Why is torque higher at low rpm?
For the same power, torque is inversely proportional to rpm, so halving rpm doubles torque.
How many N·m are in one lb-ft?
One pound-foot equals 1.3558179 newton meters.
Does it work for electric motors?
Yes. The link between power, torque and rpm is physics and applies to any rotating shaft.