Steel Beam Span / Size & Deflection Calculator

AISC W-shapes · Bending + deflection · Auto-select lightest · PDF calc sheet

Check whether an AISC W-shape passes bending stress and deflection for a simply-supported span and load, or auto-select the lightest shape that passes both. A preliminary sizing aid built on real AISC section properties — not an engineered design.

First structural-fab tool on TestTalkHQ. This opens the structural-fab vertical. It is listed on the Interactive Tools Hub and in the free-calculators structural section. Any load-bearing use — a house, an addition, anything affecting life safety — must be designed and stamped by a licensed Professional Engineer before construction.

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How to use: Enter span and load (UDL or midspan point). Set Fy and allowable Fb (defaults to 0.66×Fy). Pick a deflection limit (L/360, L/240, L/180, or custom). Choose Check a specific shape or Auto-select lightest passing, then Calculate. Export a PDF calc sheet or CSV. Read the red PE banner before treating any result as actionable.

Shop note

No genuine structural measuring tools or framing squares were in the TestTalkHQ affiliate CSV at publish time (no tape measures, framing squares, or beam-layout tools with Geniuslink URLs). Unrelated welding/electrical SKUs were intentionally omitted rather than forced onto this page.

Preliminary Only — What This Tool Does Not Do

It does not replace a licensed Professional Engineer. It assumes a fully braced compression flange and does not check lateral-torsional buckling, connections, shear, bearing, web crippling, continuous/cantilever spans, or ASCE 7 load combinations. Beam self-weight is not auto-added — include it in your load. Read the full guide or troubleshooting.

Companion Reading

Learn both modes, Fy/Fb, and deflection limits in the Steel Beam Sizing Guide. Fix common mistakes in troubleshooting. Decide mode with Check a Shape vs Auto-Select.

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