As a main course? Is this another one of your potato-themed meals?

You will have noticed over the course of your life that potatoes come in all shapes and sizes, so it is challenging for us to give you an absolute number of potatoes that will feed your baker's dozen. The standard serving size is 2/3 cup per person. In general, a pound of potato yields 2 cups of mashed, so you want to start with about 4-1/2 pounds of potatoes.

Potatoes at the market can range from 4 ounces each to more than 20 ounces, yielding less than 1/2 cup to 2-1/4 cups of cooked potato each (and that doesn't take into account some of the tiny boutique potatoes that pop up at farmer's markets and specialty stores, and which, unless you intend to keep the skin in your mashed potatoes, are fairly impractical for mashing.)

If you use large potatoes (a pound or more each), you'll need four or five. If you use medium potatoes (at about a third of a pound), you'll need around 13 potatoes. If you use small potatoes (less than a quarter-pound), you'll need around 18 potatoes. If you choose to buy by the bag, a 5-pound bag will be generous.

The U.S. Potato Board, on the other hand, suggests you use one 5-1/3-ounce potato for each person. So you would just walk into the produce section of your favorite store, reach into the 5-1/3-ounce potato bin, and select 13 of the prettiest 5-1/3-ounce potatoes. What could be simpler? Thank heavens for the U.S. Potato Board, which apparently assumes you can always find a pile of 5-1/3-ounce potatoes sitting around.

There are people in this world who consider 2/3 of a cup to be a somewhat modest serving.

You might like to try this recipe for Classic Mashed Potatoes, which will be just about right for your party if you double the recipe.