Moment of Inertia Calculator

Find the moment of inertia for common rigid shapes.

Mass

Radius

Length (rods)

Shape

Moment of inertia 0.25

Formula: I = k·m·(r or L)²

Step-by-step with your numbers:

1. Values used:

2. Mass = 2

3. Radius = 0.5

4. Length (rods) = 1

6. Moment of inertia = Radius / Mass = 0.5 / 2 = 0.25

Did we solve your problem today?

Moment of inertia measures how hard it is to change a rotating object's spin — the rotational analog of mass.

The math behind it

Each shape has a standard coefficient: I = k·m·r² (or k·m·L² for rods). More mass farther from the axis means a larger moment of inertia.

Solid cylinder, m = 2, r = 0.5 → I = ½·2·0.25 = 0.25.

Why does shape matter?

Mass distributed farther from the rotation axis resists angular acceleration more.