how long to cook lobsters
4. Cook the lobsters. Once the water has come to a boil again, begin timing the cooking of the lobsters. One-pound lobsters should cook for about 15 minutes, 1 Â½-pound lobsters for 20 minutes, and 2-pound lobsters for 25 minutes. The lobsters are finished cooking when their shells have turned bright red. Remove them from the pot and set them on a plate on their backs to dry and cool. This keeps the juices in the lobsters.