RSJ span and deflection comparison table

Compare beam sections at the exact span and uniform load you enter, using manufacturer-sourced section properties.

How to use this tool

  1. Enter the span between support centres; the tool does not round to a preset span.
  2. Enter uniform service load excluding beam weight and a deflection comparison ratio.
  3. Calculate the table. It is not a table of permissible spans or safe loads.

RSJ deflection comparison table

Simply supported beam, major-axis bending, uniform service load. This model does not establish a safe load or approve a beam size.

Beam self-weight is added automatically for each section. The ratio is an illustrative target you choose, not a universal Building Regulations limit.

Professional design required. A chartered structural engineer must determine loads, effective span, restraints, suitable section and project-specific limits. Obtain the required Building Control approval before structural work.

Data: British Steel UB datasheet, 21 July 2026. Section values, formulas and limitations.

Questions and limitations

Does a result within the target mean the beam is safe?

No. It compares elastic deflection with your chosen target only. There is no code-compliant strength or stability check, safe load rating or final beam recommendation.

Where do the section properties come from?

The tools share data transcribed from the British Steel Universal Beams datasheet dated 21 July 2026. See the methodology page for values, formulas and sources.

Can I model a point load, cantilever or continuous beam?

No. This model is restricted to a simply supported beam under a full-span uniformly distributed service load. Obtain project-specific calculations from a chartered structural engineer.

Data and editorial responsibility

Published by Krystian Welcel, a software developer. These tools have not received an independent structural engineering review. Read the data sources and calculation method.

Structural work must be designed by a chartered structural engineer and receive the applicable Building Control approval. These educational calculations are not construction specifications.