Rectangular Prism Moment of Inertia Calculator - Free Online

The moment of inertia (I) is a measure of an object's resistance to bending or rotational forces. Our calculator simplifies the complex physics behind this measurement for rectangular prisms.

To calculate the moment of inertia, you must input three key dimensions: the width (b), the height (h), and the thickness (or other dimension depending on the axis of rotation). The tool applies the standard engineering formula, which relates these cross-sectional properties.

When calculating $I$ about a horizontal axis passing through the centroid, for example, you will input the width and the height. The calculation performed is essentially $\frac{b \cdot h^3}{12}$. Simply enter your measurements (ensuring they are in consistent units like meters or inches) into the respective fields, click calculate, and our tool instantly provides the accurate moment of inertia value.

To maximize the accuracy and utility of your results, think about how the dimensions relate to the applied stress. The moment of inertia is highly sensitive to the depth or height of the cross-section.

• Maximize Depth: When designing a beam, increasing the height (the dimension that gets cubed) has a much greater impact on stiffness than simply increasing the width.
• Consistency is Key: If your project requires results in metric units (like m^4), ensure you input all dimensions in meters to receive the correct SI unit output.
• Check Assumptions: This calculator assumes a perfect rectangular cross-section. For irregular shapes, professional software or the parallel axis theorem must be used.