Reinforced concrete is one of the most common materials in construction and knowledge of the behavior of reinforced concrete with lateral reinforcement has been one of the important topics in researches. Due to the high cost of laboratory studies, researchers have tried to develop numerical methods with the help of relationships obtained from analytical researches as well as various programs including finite element codes. In most studies, moment-curvature diagrams in reinforced concrete with confined cores have been significant in studying the behavior and performance of reinforced concrete sections. In this research, using analytical relations and applying MATLAB program, a suitable algorithm for calculating the moment-curvature in reinforced concrete columns with lateral reinforcement is presented. In this algorithm, the famous Mander and Kent and Park models are used and a method for eliminating the non-confined concrete cover during the analysis is proposed. Finally, the moment-curvature was obtained for 4 sections of reinforced concrete and compared with the KSU-RC program, which show a good agreement.