Enter the flywheel moment of inertia (kg-m^2) and the angular velocity (rad/s) into the calculator to determine the Flywheel Energy. 

Flywheel Energy Formula

The following equation is used to calculate the Flywheel Energy.

Ef = .5*I*w^2


  • Where Ef is the Flywheel Energy (Joules)
  • I is the flywheel moment of inertia (kg-m^2) 
  • w is the angular velocity (rad/s) 

To calculate the kinetic energy of a flywheel, multiply the moment of inertia by the square of the angular velocity, then divide by 2.

How to Calculate Flywheel Energy?

The following two example problems outline the steps and information needed in order to calculate the Flywheel Energy.

Example Problem #1:

  1. First, determine the flywheel momentum of inertia (kg-m^2). In this example, the flywheel moment of inertia (kg-m^2) is measured to be 9.
  2. Next, determine the angular velocity (rad/s). For this problem, the angular velocity (rad/s) is calculated to be 5.
  3. Finally, calculate the Flywheel Energy using the formula above: 

Ef = .5*I*w^2

Inserting the values from above and solving the equation with the imputed values gives: 

Ef = .5*9*5^2 = 112.5 (Joules)

Example Problem #2: 

Using the same process as example problem 1, we first define the needed variables outlined by the formula. In this case, the values are provide as: 

flywheel moment of inertia (kg-m^2) = 9

angular velocity (rad/s) = 3

Entering these values into the formula or calculator above gives us: 

Ef = .5*9*3^2 = 40.5 (Joules)