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Structural Calculators

Beam Load Calculator

Reactions, maximum bending moment and shear for a simply supported beam under common loads.

Enter values

Results update as you type.

Result

Maximum bending moment

31.25 kN·m

Left reaction
25 kN
Right reaction
25 kN
Maximum shear
25 kN
Moment occurs at
2.5 m from the left
Total load
50 kN

A preliminary check only. Structural members must be designed and signed off by a qualified engineer.

About the Beam Load Calculator

A simply supported beam carries its load to two end supports. This calculator finds the reaction at each support, the maximum bending moment and the maximum shear force for a uniformly distributed load, a central point load or an off-centre point load — the three cases that cover most everyday checks.

Also known as: simply supported beam, beam reaction calculator, bending moment beam, beam capacity.

How to use this calculator

  1. Enter load type, span and the other fields.
  2. The result updates instantly as you type — press Calculate (or Enter) at any time.
  3. Review the breakdown shown under the main result.
  4. Use Copy result or Share to save the answer or send a link with your inputs.

Formula

UDL: M = wL²/8 · Central point: M = PL/4 · Offset: M = Pab/L

Worked example

Using the values pre-filled in the calculator above:

  • Load type: Uniformly distributed
  • Span = 5 m
  • Distributed load = 10 kN/m

the calculator returns:

  • Maximum bending moment: 31.25 kN·m
  • Left reaction: 25 kN
  • Right reaction: 25 kN
  • Maximum shear: 25 kN

Frequently asked questions

What is a simply supported beam?

One resting on two supports that can rotate freely — no fixed end moments. It is the standard idealisation for a joist or lintel.

Why is the moment biggest at mid-span?

For symmetric loading the shear passes through zero at mid-span, and the bending moment always peaks where the shear crosses zero.