Roasting a turkey based on a minutes per pound scale is the best way to estimate your turkey roasting time. The average cook time for a completely thawed turkey is roughly 15 minutes per pound, however, all ovens cook differently and no bird is alike. Therefore, to supplement per pound cooking, it is necessary to rely on the readings of an internal temperature thermometer to know exactly when the bird is properly cooked through to avoid both under cooking and over cooking.
Thaw the turkey. If your turkey is frozen, you must thaw it completely before placing it in the oven. The recommended method of thawing poultry is in the refrigerator as it is the safest way to prevent bacteria from forming. Refrigerator thawing times are roughly based on a scale of 24 hours per every five pounds. Therefore, a 24 lb. turkey would take about four or five days to thaw in the refrigerator. If you are running short on time, the quicker method is the cold water bath. Place the frozen turkey (still in its plastic wrapping) in a sink full of cold water. Change the water every 30 minutes. The water thawing scale is about 30 minutes per pound, therefore, a 24 lb. turkey would take about 10 to 12 hours to thaw in the cold water.
Remove the giblets and rinse the turkey thoroughly. Once the bird is cleaned, place it in a sturdy roasting pan (avoid flimsy aluminum foil disposable trays) and butter and season the skin and inner cavities with your preferred turkey seasonings, chopped herbs, onions and garlic. You can place bread stuffing inside of the turkey, however, it is not recommended by many chefs and food safety professionals as it tends to harbor bacteria.
Cook the bird in an oven preheated to 325 degrees Fahrenheit. General turkey roasting time is based on a scale of 15 minutes per pound. Therefore, an 11 lb. turkey requires about three hours of cooking time, and a 24 lb. turkey requires about five hours. Regardless of the cooking time, however, never remove a turkey that has not reached an internal temperature of at least 165 degrees Fahrenheit on a quality meat thermometer. Do not rely on the small plastic buttons some turkeys are manufactured with. Refer to the USDA (US Department of Agriculture) unstuffed turkey roasting chart below for estimated times:
8 to 12 lbs for 2 3/4 to 3 hours
12 to 14 lbs for 3 to 3 3/4 hours
14 to 18 lbs for 3 3/4 to 4 1/4 hours
18 to 20 lbs for 4 1/4 to 4 1/2 hours
20 to 24 lbs for 4 1/2 to 5 hours