The post‐buckling strength, which is simply called as crippling, is investigated for laminated composite structures in this study. L profiles that had various stacking sequences of carbon fiber reinforced epoxies were tested. Three different layups configurations were used by changing flange‐to‐thickness ratios. The main objective of this research was to show that flange‐to‐thickness ratio was not the only effecting parameter for crippling. Therefore, a new parameter, EGY number, was developed by considering the positions of 0° and 45° plies. Depending on EGY number, a new semi‐empirical formulation was presented to calculate crippling strength of the laminated composite structures. One of the test results was employed to verification of EGY number. In addition, the test results were validated with finite element analyses. Static, Riks and Dynamic, Explicit computational results were compared to simulate the experiments. Highlights Determination of crippling strength both experimentally and theoretically. Comparison of numerical models: Static, Riks versus Dynamic, Explicit. Developing a new parameter called as EGY number. Developing of a new analytical semi‐empirical formula for crippling strength. The Effect of EGY Number on Crippling Strength for Composites