Wood Beam Span Calculator

Check a timber beam span against deflection, bending, and shear limits per Eurocode 5 (EN 1995), Malta’s applicable structural timber design code.

Disclaimer

Estimate only — verify with a licensed engineer or your local building code before construction.

Wood Beam Span Calculator: Deflection, Bending and Shear Check

This calculator checks whether a wood beam of a given size, species and grade can safely carry a chosen load over a chosen span, testing deflection, bending stress and shear stress in one pass. Enter the beam's width, depth, species/grade, span, load and deflection limit, and get a pass/fail on all three. It is a planning and pre-check tool, not a substitute for a structural engineer or your local building code -- beam sizing is safety-critical, and a fully computed result is currently only available under the US NDS 2018 design standard.

How to Use the Wood Beam Span Calculator

  1. Select the design standard for your project -- US NDS 2018 is the only standard this calculator fully computes today; Eurocode 5 and AS 1720 are selectable but not yet populated with real results.
  2. Choose a nominal beam size (2x8 through 4x12) or enter a custom width and depth in inches.
  3. Pick a species/grade preset (Douglas Fir-Larch, Hem-Fir, Spruce-Pine-Fir or Southern Pine) or enter custom design values.
  4. Enter the span, the uniform load per linear foot, and a deflection limit -- L/360 is the standard default for beams.
  5. Read the pass/fail result for deflection, bending stress and shear stress.

The Math Behind the Check

Three checks run together: bending stress (fb = M/S, with M = wL^2/8 for a simply supported beam) against the adjusted bending design value; shear stress (fv = wL/(2bd)) against the adjusted shear value; and deflection (5wL^4/384EI) against your chosen limit (L/360 is standard).

Whether a beam passes depends entirely on its cross-section, species/grade, span, load and deflection limit -- there is no single "maximum span" that applies universally. This calculator computes a real result from your inputs under the US NDS 2018 method only; other design standards remain selectable placeholders until real span data is sourced for them.

Maltese Design Standard

  • Timber beam spans in Malta are designed to Eurocode 5 (EN 1995-1-1) -- this calculator's Span mode currently computes real results only using the US NDS 2018 method, so Eurocode 5 is selectable but not yet populated with real span data.

Tips and Common Mistakes

Having a structural engineer (perit) review a single beam span check typically costs around €260-€950 in Malta, depending on complexity.

  • Adjustment factors (load duration, wet service, temperature, and others) default to 1.0 -- only change them if you know your project's conditions genuinely differ from standard dry, normal-duration assumptions.
  • This is a planning aid, not a stamped structural calculation. For any load-bearing beam, confirm your final size, span and load against your applicable design standard or a licensed structural engineer before you build.