The calculation of the load-bearing capacity of thin-walled structures, including trapezoidal sheeting, normally follows the procedures of EN 1993-1-3 and similar codes. EN 1993-1-4 complements this standard for thin-walled structures made of stainless steel. Unfortunately, a buckling curve for stiffeners between the plane cross-section parts of the flanges or the webs is lacking. A finite element analysis was performed in order to obtain a buckling curve for such stiffeners. The finite element model was calibrated based on test results and by recalculating the EN 1993-1-3 buckling curve for the stiffeners in trapezoidal sheeting made of non-alloy structural steel. The results of the research into the load-bearing behaviour of thin-walled stainless steel trapezoidal sheeting presented here are closing this gap: the proposed addition to the design formulae means it is now possible to carry out a complete calculation of the load-bearing capacity of stainless steel trapezoidal sheeting.