Abstract: This study proposes a model for calculating the optimum dry film thickness of corrosion protective Coatings. It was assumed that the graph of coating thickness against corrosion rate is a parabola whose coordinates at turning point consists of optimum thickness and minimum corrosion rate. On this basis, equation of parabola was formed. Three equations of parabola were also formed with three assumed thicknesses, taking arbitrarily with their corresponding corrosion rates of the coated metals. From the equations, a 3x3 matrix was derived. From the solution of the matrix, equations for optimum thickness, minimum corrosion rates and corrosion rate of uncoated specimen were obtained. It is assumed that with this model a technical ground shall be established, upon which the optimum thicknesses of corrosion protective coatings shall be recommended.