Take the length of your room (ft) and add that with the width of your room (ft). Then simply remove the ft and put inches (without converting).
For example, a 12ft by 10ft room equals 22ft. Therefore your minimum chandelier size should be a 22" wide chandelier.
Calculating a Chandelier's Maximum Size
Take the width of your dining room table (inches) and deduct 12 inches.
For example, a 48" table should have a maximum 36" wide chandelier above it.
Why? This gives those sitting and standing head clearance space while also remaining proportionate to the space. With linear fixtures, you'll just want to be sure that the linear fixture do the same calculation using the length of the table and the length of the fixture, in stead.
Think Outside of the box
In lieu of using just a chandelier, we've had customers think outside of the box with their lighting visions.
• Use 2+ pendants over their dining room table; perhaps alternating between a pendant and a recessed can.
• Use track lighting to use a single junction box and have multiple pendants and/or track heads allowing for art lighting and task lighting all in one.