We often get asked if there is a rule of thumb for how high to hang it a chandelier or pendant over a dining table.
Some of it depends on the chandelier itself: Is it light and airy and transparent or does it have a structure that takes up more visual space?
The purpose of a chandelier over a dining table is of course to provide lighting for that immediate area. You want to create a comfortable illumination for the circle of family or friends gathered around the table. The right lighting makes your china, silverware, crystal and floral arrangements "pop" when you have a festive meal and it also allows you to use the area for other tasks like reading or playing cards. On the other hand you don't want the chandelier or pendant to overwhelm the space or even make it hard to see who is sitting across the table from you. And you want to leave room for beautiful floral arrangements or tall candelabras.
Often the chandelier or pendant is, however, asked to do more functions than just illuminating the table. It is so tempting to use the lighting for the dining table to light up the entire room. The problem is just that this inevitable leads to hanging the light too high and not getting the more intimate effect you want. Ideally a chandelier or pendant is hung so low that it primarily illuminates that immediate area. This creates a more intimate "pool of light" and makes the dining table into a focal point. Having the bottom of the light about 30" above the table focuses it on the table top and makes it possible to read comfortably.
In rooms with very high ceilings and especially in open floor plans with lots of space around the table you can add a few inches, but once you have the light 40" or more above the table it turns into more of a general ambient light and loses that special effect.