Beam Load Calculator

Calculate bending moment, shear force, deflection, and bending stress for common beam supports, materials, and loading conditions.

Beam load analysis

Enter beam geometry and load details to estimate the critical response of a rectangular beam.

Beam Type

Material

Beam Length (m)

Beam Width (mm)

Beam Height (mm)

Point Load (kN)

Load Type

Safety Factor

About beam load calculations

Beam load analysis estimates the internal actions and movement created when a structural member carries an external force. The two primary internal actions are shear force and bending moment. Shear describes the tendency for adjacent beam sections to slide, while bending moment describes the tendency for the member to curve. A useful preliminary check also calculates elastic deflection and the bending stress at the outermost fibers of a rectangular cross-section. This calculator covers three idealized support arrangements. A simply supported beam may rotate at its supports and is a common model for joists and bridge spans. A cantilever is fixed at one end and free at the other, as with a balcony or shelf bracket. A fixed-end beam is restrained against rotation at both ends. Each support arrangement has different coefficients for moment and deflection. Concentrated loads are placed at the critical location: midspan for simply supported and fixed beams, and the free end for a cantilever. A uniformly distributed load is interpreted as force per metre across the full span. The section properties come from a solid rectangular cross-section. Its second moment of area is width times height cubed divided by twelve, and its section modulus is width times height squared divided by six. Deflection uses a representative elastic modulus for the selected material. Stress utilization compares calculated bending stress with a representative material strength reduced by the entered safety factor. These nominal properties are useful for comparisons, but real products vary by grade, moisture, reinforcement, orientation, temperature, and manufacturing standard. Results are best used for education, early sizing, and checking how changes in span or depth influence behavior. Span has a particularly strong effect because point-load deflection grows with the third power of length and distributed-load deflection grows with the fourth power. Increasing beam depth is also highly effective because stiffness grows with height cubed. Do not treat this simplified calculator as a construction approval. Actual structural design must include self-weight, load combinations, lateral stability, connections, bearing, shear deformation, local code limits, and a qualified engineer's review.

Beam load examples

Beam and load	Key result	Interpretation
6 m simply supported steel beam, 50 kN center load, 200 × 400 mm	Moment 75 kN·m; shear 25 kN	A center point load splits equally between the two supports.
2 m wood cantilever, 5 kN tip load, 150 × 300 mm	Moment 10 kN·m; shear 5 kN	The maximum moment occurs at the fixed end.
4 m fixed steel beam, 8 kN/m uniform load, 200 × 300 mm	Moment 10.667 kN·m; shear 16 kN	End restraint reduces the critical moment and elastic deflection.

How to use the beam load calculator

Choose the support arrangement and material that most closely represent the beam.
Enter the clear span and the rectangular cross-section width and height.
Choose a point load or uniformly distributed load and enter its magnitude in the displayed units.
Enter a safety factor, then select Calculate Beam to review moment, shear, deflection, stress, and utilization.

Beam load calculator FAQ

Where is the point load applied?

The point load is placed at midspan for simply supported and fixed-end beams. It is placed at the free tip for a cantilever because those positions produce the standard critical cases.

What does a distributed load mean here?

A distributed load is a uniform line load entered in kilonewtons per metre. The calculator assumes that intensity acts over the beam's entire entered length.

Why does beam height change deflection so much?

A rectangular section's second moment of area increases with height cubed. Even a modest increase in depth can therefore produce a large increase in stiffness.

Does the utilization result prove the beam is safe?

No. It is only a simplified bending comparison using representative material properties and the chosen safety factor. A complete design must check codes, stability, connections, shear, bearing, load combinations, and serviceability.

Can this calculator analyze an I-beam?

Not directly, because the section formulas assume a solid rectangle. Use the manufacturer's published moment of inertia and section modulus or structural design software for an I-shaped section.