To avoid sudden and brittle failure of bending members, the Indian Standard Code prescribed limits on the minimum and maximum values of longitudinal reinforcement ratios. In the present paper, a computer program in C-language is developed for moment-curvature relationship of the reinforced concrete beams with minimum percentage of steel. The moment-curvature relationship helps in understanding the strength characteristics, flexural behaviour, and ductility characteristics of RC beams under flexure. The influence of grade of concrete, grade of steel, percentage of tension steel, and geometric parameters like depth of the beam section on the moment-curvature relation of reinforced beams is studied. Based on the Moment-curvature diagrams, it is found that the first crack moment and the ultimate moment of concrete increases with increase in the grade of concrete due to the increase in the interfacial toughness. The energy absorption capacity and curvature ductility of the concrete is found to be decreasing with the increase in the compressive of the concrete and percentage of steel due to the increase in brittleness of the concrete.