Question 1

How do I calculate maximum beam deflection?

Accepted Answer

Pick the support and load case, then enter the span L, load, modulus E and second moment of area I. Deflection scales with load and L³, and inversely with E·I — so a stiffer material or a deeper section (higher I) cuts deflection fast. For a simply-supported centre point load, δ = PL³/48EI.

Question 2

What is the difference between moment of inertia I and section modulus Z?

Accepted Answer

I (mm⁴) governs deflection; Z = I/c (mm³) governs bending stress (σ = M/Z). Get both for your cross-section from the Section Properties tool.

Question 3

Does this handle cantilever and fixed-end beams?

Accepted Answer

Yes — cantilever (end/at-a/UDL), simply supported, fixed-fixed and propped-cantilever cases are all included, each with its correct reactions, max moment, shear and deflection.

Beam Calculator

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