public static double coordGpsToKm(double lat1, double lon1, double lat2, double lon2) {        
    double lat1rad = Math.toRadians(lat1);
    double lon1rad = Math.toRadians(lon1);
    double lat2rad = Math.toRadians(lat2);
    double lon2rad = Math.toRadians(lon2);

    double difLatitud = lat1rad - lat2rad;
    double difLongitud = lon1rad - lon2rad;

    double a = Math.pow(Math.sin(difLatitud/2), 2) +
            Math.cos(lat1rad) *
            Math.cos(lat2rad) *
            Math.pow(Math.sin(difLongitud/2), 2);
    double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));

    double radioTierraKm = 6378.0;
    double distancia = radioTierraKm * c;

    return distancia;
}