Baking 4 oz lobster tails in the oven at 350 degrees will take about 12-16 minutes, if you have a 6 oz lobster tail, it will take approximately 18-20 minutes, and for an 8 oz lobster tail, you should bake it for about 24-26 minutes. The lobster tail is done baking when the internal temperature reaches 145°F and the meat becomes opaque and firm to the touch.