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Beam Size Calculator - Calculate structural beam dimensions for load support
Calculate structural beam dimensions for load support
Formulas and edge cases are reviewed against authoritative references before publication. For methodology, editorial standards, or corrections, use the links below.
Frequently asked questions
What is tributary width?
The width of floor/roof area supported by the beam, typically half the distance to adjacent supports.
LVL vs dimensional lumber?
LVL (laminated veneer lumber) is stronger and spans further than same-size dimensional lumber.
What is L/360?
Maximum allowable deflection is span/360. A 12ft beam can deflect max 0.4 inches under load.
Related tools
About this tool
Inputs
- Beam Span
- Tributary Width
- Load Type
- Beam Material
- Live Load
- Dead Load
- Floor
- Roof
- Deck
- Lumber
- LVL
- Steel
- Consult engineer
Results
- Total Load
- Minimum Section Modulus
- Recommended Beam Size
- Expected Deflection
The Beam Size Calculator is built for anyone who needs a quick, reliable answer. Enter your numbers and let the formula do the heavy lifting. Fill in beam span, tributary width, load type, beam material, live load, dead load, floor, roof, deck, lumber, lvl, steel and consult engineer and the tool handles the rest, showing you total load, minimum section modulus, recommended beam size and expected deflection within moments. Building codes and manufacturer recommendations often specify minimum quantities or coverage rates.
Brick count = wall area ÷ face area of one brick, adjusted for mortar joint thickness. People frequently need to calculate structural beam dimensions for load support but lack a quick way to do it — this tool fills that gap. Round up to the nearest whole unit when ordering materials you cannot buy in fractions. The width of floor/roof area supported by the beam, typically half the distance to adjacent supports. If the result surprises you, revisit your inputs — a mistyped digit or wrong unit is usually the culprit.