The temperature you roast a turkey at depends on the size of the turkey. See the guide below to know what to set your temperature to.  If your turkey weighs 15 to 16 pounds, roast it at: 425°F for 3 to 3 1/4 hours 400°F for 3 1/4 to 3 1/2 hours 350°F for 3 1/2 to 3 3/4 hours 325°F for 3 3/4 to 4 hours