Estimate sandwich platters for guests.
Catering sandwiches are counted in halves because that is how platters are built and how guests take them. Two and a half halves per person is the standard figure for a lunch buffet with other items on the table — the half beyond two accounts for the third of guests who take a third piece. Trays commonly hold 24 halves, so thirty guests need 75 halves and four trays. The vegetarian share is worth calculating separately and ordering as whole varieties rather than mixing a few into every tray, because vegetarian fillings run out first when they are the only option available to part of the room.
Sandwich Tray
Halves = guests x halves per guest; trays = halves / halves per tray, rounded up; vegetarian halves = total x vegetarian share%
Two and a half halves, so about one and a quarter whole sandwiches. Three halves each if sandwiches are the only substantial item on the table.
Three to five, with at least one vegetarian variety ordered whole rather than scattered. Keep one filling plain — cheese or ham — since it is always the first to go.