Users of this calculator can determine the percentage of window surface shading and the length of shade from an awning or balcony situated above the window. The calculation can be performed for any day of the year taking into account position of the sun, and it applies to the orientation of the window perpendicular to the direction of the solar rays.

The calculation serves as a basis for an assessment of daylight and sunlight, and can be used for planning window shading and lighting inside the building.