Disposable napkins are generally available in 3 different sizes: beverage, luncheon, and dinner. Some patterns may even include an item called a guest towel for formal events. Luncheon napkins may vary in size from different manufacturers, but they are generally 13"x13" when unfolded. This means that when the 13"x13" napkin is folded, it will appear to have 4 sections, or panels, and when folded it will appear as a 6.5" square. The difference in size may not sound like much, but you can definitely see the difference in person.
Luncheon napkins are very popular with birthday parties and luncheons where the entrees served are a bit lighter than a regular sit-down dinner. Luncheon napkins can be made of 1, 2 or 3 ply tissue paper. The quality increases with the number of plies. The highest quality disposable luncheon napkin is made of a soft yet thick tissue which is marketed under the name Better than Linen.
It is generally recommended that you plan for 2 napkins per guest when planning your event. Luch napkins are used more for meals during which guests will want to wipe their hands, or guests will accidentally throw away the napkin without thinking. Depending on the size of your party, you may want to look at bulk party supplies to see if the pattern you want is available so you can get tons of supplies at half the cost.