Perforations are often provided in the web and (or) flange plates of beams and columns of cold-formed steel (CFS) structural members in order to facilitate duct work, piping, and bridging. This paper is concerned with the establishment of effective design width equations for the determination of the ultimate strength of such perforated members in compression. A proven finite element model has been used to study the effects of perforation parameters on the ultimate strength of perforated members. The finite element model consists of short columns of lipped channel CFS sections, discretized using nonlinear "assumed strain" shell finite elements, and utilising experimental-based material properties models. The parametric study covers web slenderness values between 31 and 194, perforation width to web width ratios up to 0.6, and perforation height to perforation width ratios up to 3.0. Effective design width equations for plates having square perforations and elongated perforations were developed. The efficiency and accuracy of these two equations in predicting the ultimate strength of perforated CFS compression members have been verified through a comparison with the ultimate load results of several experimental studies from the literature.Key words: cold-formed steel, compressive loads, local buckling, perforations, finite element analysis, experimental, post-buckling strength, ultimate strength, effective width, design.