Quick Answer. The time it takes to steam a lobster tail depends on the weight of the lobster. A 2-ounce tail takes 10 minutes, a 4-ounce tail takes 12 minutes, a 6-ounce tail takes 15 minutes, an 8-ounce tail takes 20 minutes, and a 12-ounce tail takes 25 minutes. Anything heavier than 14 ounces generally takes more than 30 minutes to steam.