Simply Supported Beam Calculator

Calculate support reactions, total load, maximum shear, maximum bending moment, estimated deflection, and span ratio for a simply supported beam. Use this calculator for uniform loads, off-center point loads, center point loads, and combined beam loading.

Calculate Simply Supported Beam

Simply supported beam: reactions balance the load, max shear equals the largest reaction, and max moment depends on the load case.
Your result will appear here.

How the simply supported beam calculator works

Uniform load:
The calculator estimates total load, equal support reactions, maximum shear, maximum bending moment, and midspan deflection.

Point load:
The calculator estimates left and right reactions based on where the point load is placed on the span.

Combined load:
The calculator combines the uniform load and point load reactions, then estimates total shear, bending moment, and deflection.

Deflection check:
The calculator compares estimated deflection to the selected limit, such as L/360 or L/480.

Why use a simply supported beam calculator?

A simply supported beam calculator helps estimate basic beam behavior before choosing a beam size, comparing loads, or reviewing a framing layout.

It can help compare reactions, shear, bending moment, total load, point load position, deflection, span ratio, and basic load path assumptions.

What your result means

Your result shows estimated left reaction, right reaction, total load, maximum shear, maximum bending moment, maximum deflection, allowable deflection, and span ratio. These values are simplified estimates and do not replace structural design.

Simply supported beam formulas

Frequently asked questions

What is a simply supported beam?

A simply supported beam is supported at both ends and is free to bend between those supports. Common examples include basic floor beams, deck beams, joists, rafters, and headers.

How are support reactions calculated?

Support reactions are calculated by balancing vertical forces and moments. For a centered uniform load, each support carries half the total load.

Where does maximum moment occur?

For a full uniform load, maximum moment occurs near midspan. For a single point load, maximum moment occurs under the point load.

Can this calculator size a beam?

No. This calculator estimates basic beam forces and deflection. Final beam sizing depends on material, grade, section properties, shear, bending, bearing, deflection, connections, code requirements, and professional review.