In general, you should plan for about 8-10 oz of cooked lobster tail meat per person if you're serving lobster tails as your main dish - meaning two lobster tails per person, unless they are jumbo lobster tails. Most often frozen lobster tails that are readily available in grocery stores (not from specialty fishmongers, who will have larger Maine lobster tails more readily) are around 4-6 ounces, so plan on about two per person if making lobster tail your main dish.