The best size for a stainless steel napkin holder is about 6 inches by 2 inches by 5 inches. This will allow you to have a large amount of napkins available, when it’s full, without feeling like you have a large and bulky item on your table. This size also allows for use of most mass-manufactured napkin options. If you regularly use a nontraditional size of napkin, make sure to measure that and select a napkin holder that will work for that shape!