To ensure the safety of people in high voltage installation environments, it is necessary to perform a correct grounding design. This requires knowledge of the applicable soil resistivity. In most cases, it is not acceptable to assume a uniform soil, but in many cases, a two-layer soil model can be used with sufficient accuracy. Determining the parameters of a two-layer soil from surface resistivity measurements is a complex problem for which many estimation techniques have been proposed. This paper proposes a method of great simplicity to determine the parameters of a two-layer soil, based on a greedy algorithm, which results in sufficiently precise values with an iterative process in very few stages. The validity of the method is verified for three cases that have been analyzed in the literature, demonstrating a high degree of accuracy with very few iterations. In the process of calculating groundings in two-layer soils, sums of series of infinite terms are involved. In the paper, a limit is obtained for the number of terms to truncate the series with an error lower than desired.