Cohesive soil exhibits various degrees of swelling potential due to their clay contents and minerals. Many studies have been conducted to determine the degree of swelling of cohesive soil in the literature. These studies are related with the percentage of clay and colloid, plasticity index, shrinkage limit, activity, liquid limit, the water content and absorption and some of them give tables and others give graphics. In this study, the swelling potential of cohesive soil depending on liquid limit and natural water content were investigated. The graphical relation in literature was solved and a general equation between the water content and liquid limit of cohesive soil was determined for predicting swelling percentage. It is understood that the relation of swelling percentage between water content and liquid limit is not logarithmic as given in the literature, but it is an exponential equation with a -0.187w power constant N. The proposed methodology was applied to cohesive soil between Avcilar and Esenyurt. In literature classifications for swelling potential are variable and these definitions are inconsistent with each other. Whereas reliable numerical values for swelling are obtained by the proposed approach of swelling potential associated with clays water content.