The paper presents the main theoretical concepts related to methods of calculating the erosion rate for sandy dunes on natural coasts, namely, the beach equilibrium profile and incident waves. To illustrate calculations of dune erosion in the vicinity of the Coastal Research Station (CRS) in Lubiatowo, the Xbeach model (an incident wave model) was used. The calculations were carried out for hydrological and hydrodynamic conditions that accompanied Hurricane Ksawery (December 6–8, 2013). The results of the calculations were compared with the measured data. A satisfactory agreement was obtained between the predicted and measured results.