Beam Calculator

Calculate support reactions, maximum bending moment, and maximum deflection for a simply supported or cantilever beam under one load.

About Beam Calculator

This calculator applies the standard closed-form results of Euler-Bernoulli beam theory for four load cases. For a simply supported beam with uniform load w, the maximum moment is wL² ÷ 8 and the deflection is 5wL⁴ ÷ (384EI). With a central point load P they are PL ÷ 4 and PL³ ÷ (48EI). For a cantilever the values are wL² ÷ 2 and wL⁴ ÷ (8EI), or PL and PL³ ÷ (3EI). It is a study aid, not a structural design check.

How to use Beam Calculator

Fill in "Beam and load", "Span", "Load" and "Elastic modulus E", and the other options.
The result appears below and updates as you type.
Copy the result with the copy button, or download it as a file where that is offered.

Questions about Beam Calculator

What values of E and I should I enter?

E is a material property: about 200 GPa for steel, 70 for aluminium, and 8 to 14 for structural timber. I depends on the cross-section shape and is listed in section tables. For a rectangle it is width × height³ ÷ 12.

Runs in your browser. Page last updated November 12, 2026.

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