It is very important to determine the soil class correctly in the building design process. One of the most important parameters determining the earthquake loads acting on the buildings in the soil -structure interaction is the fundamental soil period. The fundamental soil period is related to the average shear wave velocity. It is seen that one of the important parameters used in the determination of soil classes in many earthquake codes is the average shear wave velocity. There are many correlations proposed in the literature and different earthquake codes for the determination of average shear wave velocity and fundamental soil period. Within the scope of the study, firstly, the approximate relations currently used in the literature were examined and compared with the solution that can be described as the exact solution. In the study, the fundamental soil period was taken as an exact solution. For the exact solution, the modified finite element transfer matrix method in the literature was used. In addition, to verify this method, transfer functions were obtained using the Transfer Function Tool program, and fundamental soil periods were found. It has been observed that the exact period values obtained by the two methods are exactly the same. In this context, 6 different methods, one of which is the exact solution, have been determined for the calculation of the fundamental soil period. In the second stage of the study, soil surveys taken from 10 different site within the borders of Edirne province were examined. Soil profiles of these sites were determined by using the soil survey results. Then, using the determined soil profiles, the performances of the relations suggested in the literature were examined. As a result of the study, it was concluded that the closest result to the final solution among earthquake regulations was realized in the correlation suggested by the Japanese Earthquake Code.