The aim of the present study is to develop a simple analytical method for calculating the ultimate strength of a stiffened panel subject to uniaxial compression. The behavior of the stiffened panel is analyzed by using a plate–stiffener combination model as representative of the stiffened panel. Three collapse modes, namely plate induced failure, stiffener induced failure and local buckling of stiffener web are considered. While several other approaches to the same problem exist, an analytical expression of ultimate strength is of value because it can explicitly show the influence of different parameters. The given formulations can be applied to stiffened plating employing all types of stiffener profiles. The Perry–Robertson approach is used to derive the criteria for plate induced and stiffener induced failures without rotation of stiffener web. The effect of possible stiffener web buckling is included through closed form expressions for predicting the elastic buckling strength of the stiffener web taking account of the influence of rotational restraints at the plate–stiffener and stiffener web–flange intersections. The web buckling strength expressions are used together with the Johnson–Ostenfeld formulation which provides a simple plasticity correction. The influence of initial imperfections (initial deflection and welding induced residual stresses) for both plating and stiffener are taken into account. As verification, the theoretical solutions from the study are compared with some existing experimental results for stiffened panel strength under uniaxial compression. As an interesting contribution, this study develops, presents, and uses a new refined procedure to reasonably accurately evaluate the effective cross sectional area of the representative plate stiffener combination in the stiffened panel. The effective width of plating between stiffeners is analytically formulated, accounting for applied compressive loads, initial deflections, and welding induced residual stresses.