Calculate beam size requirements, maximum span, and load capacity for structural beams.
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How to Use This Calculator
<h4>How to Use</h4><ol><li>Enter the beam span (distance between supports).</li><li>Enter the tributary width (area of floor/roof the beam supports on each side).</li><li>Enter live and dead loads (defaults are typical residential values).</li><li>Select the beam size and number of plies.</li></ol><h4>Important Disclaimer</h4><p><strong>This calculator provides estimates only.</strong> Always consult a qualified structural engineer for actual beam sizing. Local building codes, wood species, grade, and loading conditions all affect the final design.</p>
Common Questions
What is tributary width?
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.
What loads should I use?
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.
What does "plies" mean?
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.