Planning a graduation open house
A graduation party is usually an open house, which is a different planning problem from a party where everyone arrives at once. Guests drop in across a window, families overlap with friends, and the room is never quite at full capacity but never empty either. That is why the spread is sized for the full guest list with a buffer for the waves, rather than for the number standing in the yard at any one moment.
How much food for a graduation party
The reliable open-house spread is one main protein at about half a pound per adult, two sides, buns or a starch, chips, and a sheet-cake dessert that serves a crowd from one pan. Food that holds well at room temperature or in a slow cooker beats anything that has to be served hot to order, because you are refilling trays over hours, not plating a single seating.
Make-ahead and serve-yourself
The format rewards make-ahead, self-serve food: pulled meats and slider stations, big bowls of pasta or potato salad, a build-your-own taco or sandwich bar, and a dessert that cuts into many pieces. Set it out so guests help themselves and you stay out of the kitchen, and lean on the buffer so a late rush of relatives does not catch you short. The calculator sizes each item for the full count and rounds to pack sizes so the shopping trip is one list.