Structural Beams — How Engineers Calculate Safe Spans

Try our free Beam Deflection Calculator for instant results.

Overview

Understanding beam deflection helps you specify the right beam size and communicate effectively with structural engineers.

δ = PL³÷(48EI) for point load | δ = 5wL⁴÷(384EI) for distributed load

Standard formula used by professionals worldwide

Beam span 5m, 20kN point load, EI=2000 → δ = 26mm | Limit L/360 = 13.9mm → undersized, need larger EI

Accuracy: Results are as accurate as the inputs you provide
Units: Always use consistent units throughout your calculation
Verification: Double-check important calculations before making decisions
Professional advice: For major financial, health, or structural decisions, consult a qualified professional

L/360 for floors under live load. L/250 for general structural members.

E = material stiffness (steel > concrete > timber). I = cross-section efficiency.

Yes for load-bearing elements. These calculations are for educational purposes only.

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