Thickness is a key factor on the physical properties of the new miniaturized technology of thin film devices. Thin film physical properties depend on the thickness value and its control. This paper highlights the importance of the accurate determination of the thickness in thin films. Many efforts have been made through the years to develop reliable thickness measurement techniques. In this work, some of these techniques implemented to measure the thickness are briefly discussed. A theoretical model for film thickness determination was discussed. We proposed a simple method based on the variations of electrical resistance of a probe film to measure and control in situ the metallic film thickness with good resolution. Gold films were deposited by free evaporation and sputtering in order to apply the proposed method to measure and control the film thickness.