Typically, the proportional stress is 50% to 100% of the yield stress,

Given the material properties (Young's modulus E , yield stress s y , proportional limit s pl ) and the column geometry ( effective length L eff and radius of gyration r ), this calculator will compute the allowable stress with respect to a given safety factor.

This calculator is designed specifically for structural steel columns. Columns made by other materials (e.g. aluminum alloys) should use other formulas.