How much lamb for 15 people?

For 15 people, you typically need about 1 pound of lamb per person if it's the main course. This means you would require approximately 15 pounds of lamb. If you're serving other substantial side dishes, you could reduce this to about 0.75 pounds per person, totaling around 11-12 pounds. Always consider the specific appetites of your guests and whether there will be leftovers.