Enter the torque and speed into the calculator to determine the motor constant. The motor constant is a measure of the efficiency and performance of a motor.

Motor Constant Formula

The following formula is used to calculate the motor constant.

K_m = frac{T}{sqrt{P}}

Variables:

  • Km is the motor constant (Nm/√W)
  • T is the torque produced by the motor (Nm)
  • P is the power output of the motor (W)

To calculate the motor constant, divide the torque by the square root of the power output of the motor. The power output can be calculated from the torque and speed using the formula P = (T * ω), where ω is the angular velocity in radians per second.

What is a Motor Constant?

The motor constant (Km) is a value that represents the efficiency and performance of a motor. It is defined as the torque (T) that a motor can generate divided by the square root of the power (P) it consumes. A higher motor constant indicates a more efficient motor that can produce more torque for a given amount of power.

How to Calculate Motor Constant?

The following steps outline how to calculate the Motor Constant.

  1. First, determine the torque (T) produced by the motor in Newton-meters (Nm).
  2. Next, determine the speed (ω) of the motor in revolutions per minute (RPM).
  3. Convert the speed to radians per second by multiplying by (2π/60).
  4. Calculate the power output (P) of the motor using the formula P = T * ω.
  5. Finally, calculate the Motor Constant (Km) using the formula Km = T / √P.
  6. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Torque (T) = 0.5 Nm

Speed (ω) = 3000 RPM