Motor torque calculator from power and speed
Read the power and speed from the motor nameplate and get the rated torque. Works for electric motors and engines alike.
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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 and rotational 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
T = P ÷ ω with ω = 2π n ÷ 60, so T (N·m) = 60000 × P (kW) ÷ (2π n) ≈ 9549 × P ÷ n.
Example
Inputs: Power = 7.5 kW, Rotational speed = 1,450 rpm. Result: Torque: 49.393 N·m; Torque in lbf·ft: 36.43 lbf·ft; Power in horsepower: 10.058 hp.
Limits and caveats
- Gives torque at the entered power and speed only; starting and peak torque differ.
- Uses mechanical horsepower (745.7 W); metric horsepower is 735.5 W.
Questions about this tool
Where does 9549 come from?
It is 60000 ÷ 2π, which turns kW and rpm straight into N·m.
What torque does a 1 hp motor give at 1450 rpm?
1 hp is about 0.7457 kW, so the torque is about 4.91 N·m.
Why is torque higher at low speed?
At the same power, torque is inversely proportional to speed, which is why gearboxes cut speed to raise torque.