Select a shape and enter dimensions, then click Calculate.

The moment of inertia (second moment of area) is a geometric property that measures a shape's resistance to bending and deflection. It is denoted by I and is expressed in units of length to the fourth power (m⁴, cm⁴, in⁴). For rectangular cross-sections, I = b·h³/12 about the centroidal axis and I = b·h³/3 about the base axis. For circular cross-sections, I = π·r⁴/4 about the centroidal axis. The moment of inertia is essential in structural engineering, mechanical design, and physics for calculating beam deflections, buckling loads, and stress distributions. This calculator provides quick values for common shapes with the axis through the centroid or at the base.

1. Select the Shape (Rectangle, Circle, Tube, Triangle, or Hollow Rectangle).
2. Select the Axis (Through Centroid or At Base).
3. Enter the required Dimensions (labels change based on shape).
4. Click Calculate to compute the moment of inertia.
5. The result shows the value in units⁴ and the formula used.
6. Click Reset to restore default example values.