First you should determine how far you want your tablecloth to drop from the edge of the table. We recommend at least 8 to 10 inches drop for more casual events, and up to 15 inches for formal dinner parties. For rectangular tables, simply multiply your desired drop by two (for example, 10 inches of drop x 2 = 20) and add that number to both the width and the height dimensions of your table. This is the size of tablecloth that you need. For a round table, multiply the desired drop by two as before, but then add that number to the table’s overall diameter. If you don’t find the exact size you need, simply order the next largest size.