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Slenderness Ratio Calculator
Calculate a column’s slenderness ratio to assess its buckling tendency.
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Column Slenderness Ratio
The slenderness ratio predicts whether a column will fail by crushing (short, stocky columns) or by buckling (long, slender columns). It’s calculated as λ = KL / r, where K is the effective length factor (depending on end support conditions), L is the unsupported length, and r is the radius of gyration of the cross-section.
A low slenderness ratio (roughly under 40) indicates a short column governed by material strength, while a high ratio (over about 120) indicates a slender column governed by elastic (Euler) buckling. Intermediate values fall into a transition zone where both effects matter. This is a standard structural engineering reference calculation.
Last reviewed August 2026