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Cold-Formed Steel (CFS) C-Stud Deflection Checker

Check a cold-formed steel stud's calculated lateral (wind) deflection against a code deflection limit.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax
9.84 ft
Schematic, drawn to the proportions you entered — not to scale on screen.

Calculated stud deflection

0.03 in

High confidence

PASSES — calculated deflection (0.79 mm) is within the 12.50 mm allowable limit. Make sure I_eff came from the manufacturer's or AISI S100 span table for your exact stud size and gauge, not an assumed value.

Allowable limit
0.49 in

For the dimensions entered, expect a calculated stud deflection of 0.79 mm. Of the working steps, allowable limit dominates at 12.5 mm. Note that effective moment of inertia i_eff (×10⁶ mm⁴) sits at the low end of the range this calculator was checked against, so treat the output as indicative rather than settled. Set for United States against IRC 2024. The market selector changes both the units and the code cited.

Add the equipment this sizes

This result is a specification — 0.031 in — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • AISI S100 governs how a CFS stud's effective section properties (I_eff) are derived, but the deflection check itself is standard elastic beam theory: Δ = 5wL⁴/(384EI_eff); manufacturers (SSMA, ClarkDietrich) publish I_eff per stud size/gauge in their span tables for use in this formula

Your workspace

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Frequently asked questions

Where does the effective moment of inertia (I_eff) come from?
I_eff is not a simple geometric property you can compute from the stud's nominal dimensions — AISI S100 requires it to be derived from the stud's effective (post-local-buckling) section properties, which manufacturers like SSMA or ClarkDietrich publish per stud size and gauge in their span tables.
Why do brittle finishes need a tighter deflection limit (L/600)?
Rigid or brittle wall finishes (tile, stucco, some gypsum assemblies) crack under smaller amounts of stud movement than more flexible finishes, so codes and manufacturers commonly specify a tighter L/600 limit for studs behind those finishes versus the more common L/240 or L/360.
Does passing this deflection check confirm the stud is structurally adequate overall?
No — this checks lateral (wind) deflection serviceability only. The stud's bending and axial capacity (including any gravity load it also carries) must be checked separately per AISI S100 to confirm overall structural adequacy.