To calculate the length of day throughout the year, you have to click on the map on the corresponding position or enter the desired address in the address-field. With the country menu on the left side, any country can be selected, which is then displayed on the map itself. Subsequently, the day length during the year can be calculated for the desired position. This requires that the button on the bottom edge of the card to be pressed. The result of the calculation consist of three graphs, which shows the length of day, sunrise and sunset throughout the year.For the calculation of sunrise, sunset and day length, the height, the timezone and the surrounding topography are considered.