Within the framework of the Ritz method, the quantum-statistical functional, and the stabilized jellium model, the problem of calculating the surface energy per unit area, the electron and positron work function, and the Schottky barrier height for a metal with a dielectric coating is considered. The calculated values are in satisfactory agreement with both experimental data and the results of the Kohn–Sham calculations. The simplest inhomogeneous dielectric coatings are considered. The connection between the Ritz theory for inhomogeneous coatings and the Kohn–Sham theory for the surface characteristics of metal–dielectric nanosandwiches is established. Invited to take into account the effect of inhomogeneous coating on the metal surface characteristics by scaling a uniform coverage case. The effect of dielectric confinement for the energy characteristics of the asymmetric metal–dielectric sandwiches is reduced to the weighted average value of the dielectric constants. The possibility of application the obtained results in various experimental situations is discussed.