The size of a ceiling fan is determined by its blade span. The blade span ranges from 29 to 54 inches. The most popular size is the 52-inch models.
Room size should be translated to square feet by multiplying the width of the room by its length. For example, a 10 by 16 foot room is 160 square feet. Use the square footage to determine the proper fan size necessary for the room.
Use a 29- to 36-inch ceiling fan for a room that is less than 75 square feet. A 36- to 42-inch fan is ideal for a room between 76 and 144 square feet. A 44-inch fan is suggested for a room size of 144 to 225 square feet. If the room is between 225 and 400 square feet, use a fan that is 50 to 54 inches.