Beam deflection calculator
Calculate the maximum midspan deflection of a simply supported beam under a uniform load or a center point load.
How it is calculated
Uniform: δ = 5wL⁴ ÷ (384EI). Center point: δ = PL³ ÷ (48EI).
Worked example
Steel, L 4 m, I 1000 cm⁴, w 1000 N/m: δ = 1.67 mm.
Steps
- Choose the load type.
- Enter span, E and I in the units shown.
- Read the deflection in mm and compare it to your limit (often L/360).
Frequently asked questions
Is the result the maximum deflection?
Yes, at midspan for a simply supported beam with a symmetric load.
Where do I get I?
From the section table of the profile, for example the steel handbook.
Does this include self-weight?
No. Add the beam weight per meter to w if it matters.
References
Standard beam formulas (Roark, Formulas for Stress and Strain; Timoshenko).
Estimates for information only. Verify critical values with a qualified engineer or your supplier standards.