The average turkey should roast for around 2 3/4 hours to 3 1/2 hours. The exact time depends on the size.
A 10- to 12-pound turkey breast, unstuffed, should roast for 2 1/2 hours to 3 hours. Stuffed, it takes around 3 to 3 1/2 hours. A large turkey over 24 pounds will need to cook for approximately 3 3/4 to 4 1/2 hours if unstuffed and 4 1/4 to 5 hours if stuffed. These cooking times are based on a temperature of 325 degrees Fahrenheit. Using a roasting bag to cook the turkey breast in can reduce the cooking times by at least 1 hour.