Motor Torque Calculator

Enter your Motor Power and Motor Speed, choose your preferred Power Unit and Torque Unit, and the Motor Torque Calculator works out the Motor Torque your motor produces — along with Power and Angular Velocity as handy bonus outputs.

kW

Motor's rated power from nameplate or datasheet

RPM

Motor's rated speed from nameplate (not synchronous speed)

Results

Motor Torque

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Power

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Angular Velocity

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Frequently Asked Questions

How do you calculate motor torque?

Motor torque is calculated using the formula: T = (60 × P × 1000) / (2π × N), where T is torque in N·m, P is power in kW, and N is speed in RPM. This formula relates the motor's rated power and speed to determine its torque output.

What is the difference between motor torque and engine torque?

Motor torque refers to electric motors and is calculated from electrical power ratings, while engine torque typically refers to internal combustion engines. Both represent rotational force, but electric motors provide constant torque at rated conditions, whereas engines have torque curves that vary with RPM.

How much torque does a 1 HP motor produce?

A 1 HP motor's torque depends on its speed. At 1800 RPM, a 1 HP motor produces approximately 4.2 N·m (3.1 ft-lbs) of torque. Lower speeds result in higher torque, following the inverse relationship between power, speed, and torque.

What is rated torque vs. starting torque?

Rated torque is the continuous torque a motor can produce at its rated power and speed during normal operation. Starting torque is the torque available when the motor starts from rest, which is typically 1.5-3 times higher than rated torque for most electric motors.

Why is motor speed important for torque calculation?

Motor speed (RPM) is inversely related to torque for a given power. At constant power, higher speeds result in lower torque, and lower speeds produce higher torque. This relationship is fundamental to motor selection for specific applications.

What is slip in electric motors?

Slip is the difference between synchronous speed and actual rotor speed in AC induction motors, expressed as a percentage. Slip allows the motor to produce torque - without slip, there would be no relative motion between the magnetic field and rotor, resulting in zero torque.

How do you convert between N·m and ft-lbs for torque?

To convert torque units: 1 N·m = 0.7376 ft-lbs, and 1 ft-lb = 1.356 N·m. Multiply N·m by 0.7376 to get ft-lbs, or multiply ft-lbs by 1.356 to get N·m. Both units measure rotational force but are used in different engineering standards.

What factors affect actual motor torque output?

Actual motor torque can be affected by voltage variations, frequency changes, temperature, motor condition, and load characteristics. The calculated rated torque assumes ideal conditions - real-world performance may vary due to these factors and mechanical losses.

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