The volumetric behavior of sands during differential deformation, referred to as dilatancy or dilation, is considered one of the complex subjects in soil mechanics. Considering the influence of soil volumetric behavior on distortional deformation requires the definition of a differential stress–strain relationship in addition to a relationship between the increment of plastic strain and the increment of volumetric strain. Many investigations have shown that the stress ratio is one of the principal variables governing this relationship, referred to as the stress–dilatancy relationship. In the interpretation of laboratory test results, the evaluation of dilatancy requires the determination of plastic strain increments. The separation of plastic strain increments from total strain also necessitates an accurate estimation of elastic strain increments. Various elastic models have been proposed for determining elastic strain increments during elastoplastic deformation. In the present study, it is demonstrated that the selection of elastic models can significantly influence stress–dilatancy relationship. This research investigates the stress–dilatancy behavior of Karlsruhe sand under semi-cyclic loading conditions. To evaluate the influence of methods used for determining elastic strain increments on the stress–dilatancy relationship, four different approaches are examined. In the first and second approaches, the elastic bulk modulus is defined using two different functions of mean effective stress. In the third approach, a constant bulk modulus is assumed, and in the fourth approach, the coupling effect between volumetric and shear strains is considered. The obtained results are evaluated against stress–dilatancy relationships, including Roscoe’s energy dissipation relationship, Rowe’s stress–dilatancy relationship, the sliding block theory, Taylor’s energy dissipation equations, and the two-surface yield model.