Moment of Inertia Calculator
Calculate moment of inertia, section modulus, and radius of gyration for rectangular sections
in
Horizontal dimension
in
Vertical dimension (depth)
Cross-Section Properties
Moment of Inertia (Ix)864in⁴
Moment of Inertia (Iy)216in⁴
Section Modulus (Sx)144in³
Section Modulus (Sy)72in³
Radius of Gyration (rx)3.464in
Area (A)72in²
Formulas Used
Ix = b × d³ / 12
Iy = b³ × d / 12
Sx = b × d² / 6
Sy = b² × d / 6
r = √(Ix / A)
Note
Ix is about the strong axis (bending about x-axis, horizontal neutral axis). Iy is about the weak axis. For standard beams loaded vertically, Ix is the governing moment of inertia.
Disclaimer: These calculations are for educational and preliminary design purposes only. Always verify results with qualified engineering analysis before use in actual construction.