Beam Load Calculator
Calculate maximum bending moment and deflection for a simply-supported beam under a uniform or point load — a quick structural sanity check.
Maximum bending moment
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Maximum deflection —
Deflection ratio (span/deflection) —
Simplified simply-supported beam formulas only. Not a substitute for a licensed structural engineer's analysis.
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How it works
Uniform load: M = wL²/8, deflection = 5wL⁴/(384EI); point load at center: M = PL/4, deflection = PL³/(48EI)Frequently Asked Questions
How do I calculate the maximum bending moment on a beam?
For a simply-supported beam with a uniform load, M = wL²/8, where w is load per unit length and L is span. For a single point load at midspan, M = PL/4. Both give the maximum moment at the center of the span.
How do I calculate beam deflection?
Deflection depends on load, span, and the beam's stiffness (E × I, modulus of elasticity times moment of inertia): δ = 5wL⁴/(384EI) for uniform load, or PL³/(48EI) for a center point load — stiffer or shorter beams deflect less.
Is this a substitute for professional structural engineering?
No — this is a simplified check for simply-supported beams under basic loading only. Real structures involve load combinations, safety factors, material properties, and connections that require a licensed structural engineer.