A beam span and load calculator that works out the maximum span, beam size and load-bearing capacity for structural beams.
This calculator provides estimates only. Always consult a qualified structural engineer for actual beam sizing. Local building codes, wood species, grade, and loading conditions all affect the final design.
The tributary width is half the distance between the beam and the next parallel support on each side. For example, if joists span 12 ft on each side of a beam, the tributary width is 12 ft.
For residential floors: 40 psf (1.92 kPa) live load and 10–15 psf (0.48–0.72 kPa) dead load. For roofs: 20–40 psf depending on snow loads.
Plies refers to the number of boards bolted together to form a built-up beam. A 2-ply 2×10 is two 2×10 boards laminated together.
Yes. This tool gives a useful guide, but any load-bearing beam in a building should be sized and signed off by a qualified structural engineer.
A distributed load is spread evenly along the beam (like a floor), while a point load is concentrated at one spot (like a post). They affect beam sizing differently.
