Mass Moment of Inertia Calculator (Point Mass)

Enter the mass of a point object and the distance or length from the point to the center of rotation to calculate the mass moment of inertia.

Mass Moment of Inertia Formula

The following formula is used by the calculator above to determine the mass moment of inertia.

I = m * r²

  • Where i is the moment of inertia of a point mass (kg*m^2)
  • m is the mass (kg)
  • r is the distance between the point of rotation to the point mass.

This formula is used specifically for a point mass. A point mass is a non-dimensional point in space representing a larger object. In most cases this point mass is the center of mass of some object.

For example, if you had a sphere with equally distributed weight, that sphere could be represent as a point mass of the total weight at the very center of that sphere. For irregular objects it is much more difficult, but in the end, all objects can be simplified into a point mass.

How to calculate a mass moment of Inertia

  1. First, measure the mass of the object

    Using a scale or formula, determine the total mass of the object.

  2. Next, measure the radius

    This will be the radius from the point of rotation to the point of pass, or center of mass.

  3. Calculate the momentum of inertia.

    Enter the mass and radius into the formula I = m * r² to calculate the momentum of inertia.

Mass Moment of Inertia Calculator