# Beam Load Calculator Calculate beam load capacity for 2x8, 2x10, 2x12 lumber, LVL, and steel beams. Get max uniform load, point load, deflection, and recommended uses by span. ## What this calculates Selecting the right beam for a given span and load is one of the most important structural decisions in construction. This simplified calculator estimates maximum uniform and point loads for common dimensional lumber, LVL (laminated veneer lumber), and steel beams based on allowable bending stress and span length. ## Inputs - **Beam Type** — options: 2x8 (Douglas Fir #2), 2x10 (Douglas Fir #2), 2x12 (Douglas Fir #2), LVL 1.75" x 9.25", LVL 1.75" x 11.25", Steel W8x18 — Select beam size and material - **Span Length** (ft) — min 2, max 40 — Clear span between supports - **Load Type** — options: Uniform (distributed along beam), Center Point (single load at midspan) — How the load is applied to the beam - **Number of Plies** — min 1, max 4 — Number of beams laminated together (1-4) ## Outputs - **Max Uniform Load** (lbs/ft) — Maximum distributed load per linear foot (strength limited) - **Max Point Load** (lbs) — Maximum single load at midspan (strength limited) - **Deflection at Max Load** (in) — Midspan deflection under maximum load - **Recommended Use** — formatted as text — Typical applications for this beam at this span ## Details Beam capacity is governed by bending stress and deflection. The maximum bending moment a beam can resist is M = Fb × S, where Fb is the allowable bending stress and S is the section modulus (S = bd²/6 for rectangular sections). For uniform loads, M = wL²/8; for center point loads, M = PL/4. Douglas Fir #2 lumber has an allowable bending stress of about 1,000 psi. LVL (laminated veneer lumber) is significantly stronger at 2,600 psi, making it ideal for headers and long-span beams. Steel W-shapes have allowable bending stresses around 24,000 psi, enabling long spans with compact sections. Multiple plies increase capacity linearly: a doubled (2-ply) 2x10 beam carries twice the load of a single 2x10. This is common practice for floor girders and headers. For critical structural applications, always have a licensed structural engineer verify beam sizing. This calculator provides estimates based on simplified analysis and does not account for all code requirements including lateral bracing, shear, bearing, and load duration factors. ## Frequently Asked Questions **Q: How far can a 2x10 beam span?** A: A single Douglas Fir #2 2x10 can span about 8-12 feet for floor joists (40 psf live load at 16" OC spacing) or 6-8 feet as a beam/header depending on the load. A doubled 2x10 (2-ply) extends the header span to 8-10 feet. Always verify with span tables or an engineer for your specific loading conditions. **Q: What is the difference between a beam and a joist?** A: Both are horizontal structural members, but they serve different roles. Joists are repetitive, closely-spaced members (typically 16" or 24" OC) that carry floor or ceiling loads to beams or walls. Beams (girders) are larger members that carry concentrated loads from joists, headers, or other beams to posts or bearing walls. **Q: When should I use LVL instead of dimensional lumber?** A: LVL (laminated veneer lumber) is stronger, straighter, and more consistent than dimensional lumber. Use LVL for spans over 8-10 feet, headers over window and door openings in load-bearing walls, floor girders, and any application where deflection or straightness is critical. LVL costs more per piece but often allows a smaller beam size. **Q: What is deflection and why does it matter?** A: Deflection is the amount a beam bends under load, measured at midspan. Building codes typically limit deflection to L/360 for floors (span divided by 360) and L/240 for roofs. A 10-foot floor beam can deflect no more than 0.33 inches. Excessive deflection causes bouncy floors, cracked drywall, and stuck doors even if the beam is structurally safe. --- Source: https://vastcalc.com/calculators/construction/beam-load Category: Construction Last updated: 2026-04-21