Resonant inductive coupling (RIC) systems have undergone a remarkable improvement thanks to several research efforts. Nevertheless, practical difficulties and stringent design requirements still present several limitations and challenges to overcome. One of the important concerns is how to design the coils for the desired power level with a high efficiency considering all design constraints and parameters, i.e.The number of turns, the frequency, the air gap, etc. A planar spiral coil can be considered as an inductance connected in series with internal resistance. The coil resistance significantly decreases the power transfer efficiency (PTE) in resonant inductive coupling wireless power transfer (RIC WPT) applications, since it leads to power losses. In this paper, we have suggested a numerical optimization method based on genetic algorithms (GA) that gives the best coil parameters ensuring the highest coil quality factor, by respecting the system design constraints such as the frequency and the used material. In this paper, we propose a model for a silver planar spiral coil and an operating frequency of 100 kHz, following the Qi guidelines. Obtained results show the efficiency of genetic algorithms for giving the optimal solution for designing spiral coils, without the need to simplify the model function.