Choosing the right size ceiling fan for your room is important to ensure that it effectively circulates the air. To determine the right size, measure the room's square footage and refer to a size chart provided by the manufacturer. As a general rule of thumb, for rooms up to 75 square feet, use a 29-36 inch fan, for rooms up to 144 square feet, use a 36-42 inch fan, and for rooms up to 225 square feet, use a 44-inch fan. For larger rooms, choose a fan with a blade span of 50 inches or more.