Calculating Ceiling Medallion Size
First you need to calculate the appropriate size medallion for your room. Take the room length multiplied by the room width, divided by 7. That would equal your ceiling medallion diameter in inches. Example: A room that is 12 x 18 = 216 sq. ft., divided by 7 = 31" diameter.
What about lighting fixtures?
For best results, medallion should be larger or smaller than the lighting fixture diameter for a triangular effect.
What about ceiling fans?
Medallion should be smaller than fixture diameter.
Things to consider...
Ceiling height: An eight-foot ceiling may require a smaller medallion; A taller entry foyer could require a larger one.