Physics

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Electric Motor Torque Calculator.

Calculate shaft torque from mechanical power and rotational speed.

On-device calculationNo signup
01

Set your values

Results update as you type.

Torque: 3.183099

Torque

0.000000
Angular velocity: 314.159265

Angular velocity

0.000000

Educational SI model using the assumptions stated above; verify engineering and safety decisions independently.

Use Cases

Motor Sizing for Applications

Determine the required torque for a given power and speed to select an appropriate motor for conveyors, pumps, or fans.

Example: A 2 kW motor running at 1500 rpm produces about 12.73 N·m of torque.

Performance Verification

Check if a motor's torque output matches its specifications or to compare different motors for a project.

Example: Verify that a 500 W motor at 3000 rpm delivers 1.59 N·m as expected.

Frequently Asked Questions

How do I calculate torque from power and speed?
Use the formula: Torque (N·m) = (Power in watts × 60) / (2π × Speed in rpm). This calculator applies that formula directly. Enter mechanical power in watts and rotational speed in rpm, then click calculate to get the shaft torque.
What units are used for torque in this calculator?
The calculator outputs torque in newton-meters (N·m). It uses the standard SI units for power (watts) and speed (revolutions per minute). If you need torque in other units like lb-ft, you can convert N·m by multiplying by 0.73756.
Can I use this calculator for any type of motor?
Yes, this calculator works for any motor or rotating machine where you know the mechanical power output and rotational speed. It is commonly used for electric motors, but also applies to engines, turbines, or gearboxes, as long as you have the power and speed values.

Tips & Common Mistakes

Tips

  • Ensure power is in watts (W). If you have power in kilowatts, multiply by 1000 before entering.
  • Use the actual operating speed in rpm, not the rated speed, for accurate torque at that condition.
  • Remember that torque and speed are inversely related for a given power: higher speed means lower torque.
  • For gearboxes, use the output speed and output power to find the torque at the output shaft.

Common Mistakes to Avoid

  • Forgetting to convert power from kilowatts to watts, leading to torque values 1000 times too small.
  • Using the motor's input power (electrical) instead of mechanical power output, which overestimates torque.
  • Mixing up speed units: using rad/s instead of rpm without conversion, giving incorrect results.

Last updated: August 13, 2026