Electric Motor Torque Calculator
Calculate motor torque from power, speed, and electrical parameters for AC and DC motors
Calculate Electric Motor Torque
Motor output power
Actual motor rotational speed
AC power supply frequency
Motor magnetic poles (even number)
Select desired unit for torque output
Motor Torque Results
Motor Parameters
Motor Analysis
Example Calculation
1 HP Motor at 60Hz
Power: 1 HP (745.7 W)
Frequency: 60 Hz
Poles: 4 poles
Synchronous Speed: 1800 rpm
Actual Speed: ~1750 rpm (2.8% slip)
Calculation
T = (60 × P) / (2π × rpm)
T = (60 × 745.7) / (2π × 1750)
T = 4.07 N⋅m
Motor Formulas
T = (60 × P) / (2π × rpm)
Torque from power and speed
Basic motor torque formula
n_sync = (120 × f) / p
Synchronous speed
AC motor theoretical speed
s = (n_sync - n) / n_sync
Motor slip calculation
AC induction motor slip
Common Motor Specs
Understanding Electric Motor Torque
What is Motor Torque?
Electric motor torque is the rotational force that a motor develops to overcome load resistance. It's the turning effect that allows motors to rotate shafts, drive pumps, fans, and other machinery. Torque is directly related to the motor's power output and rotational speed.
AC vs DC Motor Characteristics
- •AC Motors: Maximum torque at specific slip, breakdown torque phenomenon
- •DC Motors: High starting torque, linear torque-speed relationship
- •Slip: Difference between synchronous and actual speed in AC motors
Motor Design Factors
T = (60 × P) / (2π × n)
Torque = (60 × Power) / (2π × Speed)
Design Rule: More poles = lower speed + higher torque. This is why high-torque applications use multi-pole motors.
Starting Torque
The torque available when the motor starts from rest. Critical for applications requiring high initial force to overcome static friction.
Breakdown Torque
Maximum torque an AC motor can develop. Beyond this point, the motor speed drops rapidly and may stall if load exceeds breakdown torque.
Full Load Torque
Rated torque at full load conditions. This is the nominal operating point where the motor delivers its rated power at rated speed.