The amount of popcorn to order for a wedding depends on the number of guests you plan to have at your reception.
In general, you should plan one to two cups of gourmet popcorn per person. So, for example, if you have 200 guests, you should order up to 400 popcorn cups, bags, or boxes.
Keep in mind that one gallon of pre-popped popcorn typically contains about 16 cups of popcorn. However, one pound of un-popped popcorn kernels will make roughly 60 cups of popped popcorn.