If a 20-pound turkey is stuffed, the roasting time is between six to six-and-a-half hours; if it's not stuffed, the turkey roasting time varies between five and six hours. After the turkey is ready, it needs to rest for 30 minutes before being served.
Once the turkey is fully prepared for roasting, it's important to return it to the refrigerator for around four hours before beginning the cooking process. This is intended to fully dry out the skin, making the turkey crispier and tastier after cooking it for the appropriate amount of time. After this cooling process, the turkey should be removed and allowed to return to room temperature, a process of about one hour for a 20-pound turkey. During this period, the oven should be preheated to 450 degrees Fahrenheit.
First,the turkey gets roasted for 30 minutes uncovered and the basting process begins. After the initial 30 minutes, the temperature should be reduced to 350 F. It's necessary to cover the turkey with aluminum foil and let it finish the cooking process, which should be around five more hours for a 20-pound turkey. The turkey is finished when it has an internal temperature of 165 F. After cooking, the turkey should be allowed to rest so that it reabsorbs its juices.