Unsaturated expansive soils undergo a volume change due to the physical-chemical reaction produced by variations in their water content. The stress-strain behavior of these soils is very sensitive to this variation, for which reason, buildings constructed on expansive soils present structural problems due to the repetitive stresses produced by shrink-swell cycles caused, in turn, by drying-wetting cycles that generate suction, water content variations and hysteresis cycles. This last phenomenon is generated by water flow through the soil, causing drying-wetting paths, thus requiring knowledge of the real cycles to which the soil has been exposed. While the hydraulic behavior of soil can now be estimated via indirect theoretical models developed to fit the Soil-Water Retention Curve (SWRC) for a soil, the adjustments obtained have a low correlation with experimental SWRC results. The present study compares the most common methods for determining secondary hysteresis cycles based on the fitting of SWRC, two of which are based on predetermined expressions. The other method applied a polynomial fit based on an arrangement table using both methods of interpolation with variable increments and Lagrange’s interpolation, resulting in a polynomial fit that generates the numerical SWRC. The results obtained were compared with the experimental results and data reported by other authors. The results show that the main and secondary cycles were consistent with those reported by other authors for sandy and silty soils; however, for clayey soils, only the polynomial method was capable of identifying hysteresis, while the process of fitting the SWRC is unnecessary with the polynomial method, resulting in a quick and easy tool that obtains consistent results.