📏 Section Modulus Calculator
Calculate the elastic section modulus for rectangular or circular beam cross-sections.
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Elastic Section Modulus
The section modulus (S) describes a beam cross-section’s resistance to bending, used to find bending stress via σ = M/S, where M is the bending moment. For a rectangular section, S = bh2/6, where b is the width and h is the height (in the bending direction). For a solid circular section, S = πd3/32, where d is the diameter.
A larger section modulus means the beam can carry a larger bending moment for the same allowable stress. Section modulus depends only on the shape and size of the cross-section, not the material, which is why it’s paired with material yield strength to find safe load limits.
Last reviewed August 2026