This study describes a method to quantify the visual impact of an offshore wind farm, as seen from the coast. In brief, the method involves distinguishing between the visual impact due to the intrusion in the observer's vision field and the un-aesthetic effect of the arrangement unevenness. Both parameters, visual intrusion and unevenness, can be quantifiable; therefore, a final indicator for the visual impact of the wind farm can be calculated for a specific wind farm layout. Two approaches are presented to calculate the visual intrusion, which give rise to similar results. The method has been programmed and included in an application that has been tested with two known wind farm layouts, showing a complete coherence of the results given by the method. This method provides the designer with a tool that allows him to take into account the estimated visual impact of a wind farm under study. If an algorithm is used to look for the optimum location/layout for an offshore wind farm, its programmer can include this method in order to obtain a trade-off between maximum profitability and minimum visual impact.