The most important function of a chandelier is to properly light the area where the fixture is mounted. In a dining room, there are usually secondary lights to provide lighting around the perimeter of the table, and the chandeliers are used for light directly on the table surface. If a chandelier is too big, too small or positioned too high or off to one side, then the table will not be properly lit.
Chandeliers are often used in areas other than the dining room. In these applications, the fixture is usually centered on the area of the room where its light is being used. For some rooms, this means there will be rows of chandeliers, each lighting an area and overlapping into the lighting area of the adjacent fixtures. These fixtures look best when the fixture arrangement makes sense visually. In a master bathroom, the fixture may be centered over the sink area or tub area, while pot lights are used for additional illumination in the rest of the room. A chandelier placed to one side over a table is likely to look awkward and unfinished.
Lighting designers use calculators to determine the amount of light or size of chandelier required to work well in a room. The width of a chandelier is calculated by measuring the length and width of the room. If a room is 12 by 12 feet square, the designer will add 12 plus 12 to get 24 and estimate that a fixture 24 to 28 inches wide will work well in the space.
The height of a chandelier is also calculated. Measure the ceiling height of the room at its tallest point. Calculate 2-1/2 to 3 inches per foot of height for the height of the fixture when you are using a single fixture. When you are using multiple fixtures, you combine the measurements so that you create the same visual effect even if the fixtures are spread out. Designers will usually go larger in larger rooms if they feel a fixture looks thin or too small. Chandeliers are also placed at any location to highlight some aspect of that location. The location can be as mundane as a kitchen sink.