Figure on a third of a pound per sandwich, then try to guess how many sandwiches each guest will eat. If they have salads and lots of other side dishes to choose from and grand desserts to look forward to, many people may eat only one sandwich.

If you have particularly big eaters (an overabundance of teenagers or a sports team, perhaps), plan on two or more per guest. Assuming they average 1.5 sandwiches each, 50 pounds of meat will be enough.