Enter the shear stress (N/m^2), the polar moment of inertia (m^4), and the radius (m) into the calculator to determine the Shaft Torque. 

Shaft Torque Formula

The following formula is used to calculate the Shaft Torque.

Tshaft = ss * J/r

  • Where Tshaft is the Shaft Torque (N-m)
  • ss is the shear stress (N/m^2) 
  • J is the polar moment of inertia (m^4) 
  • r is the radius (m) 

How to Calculate Shaft Torque?

The following example problems outline how to calculate Shaft Torque.

Example Problem #1

  1. First, determine the shear stress (N/m^2). In this example, the shear stress (N/m^2) is determined to be 500 .
  2. Next, determine the polar moment of inertia (m^4). For this problem, the polar moment of inertia (m^4) is measured to be 30 .
  3. Next, determine the radius (m). In this case, the radius (m) is found to be 4.
  4. Finally, calculate the Shaft Torque using the formula above: 

Tshaft = ss * J/r

Inserting the values from above and solving yields: 

Tshaft = 500 * 30/4 = 3,750 (N-m)


Example Problem #2

Using the same method as above, determine the variables required by the formula. For this example problem, these are:

shear stress (N/m^2) = 750

polar moment of inertia (m^4) = 10

radius (m) = 50

Enter these given values into the calculator or above yields: 

Tshaft = 750 * 10/50 = 150 (N-m)