The amount of time needed to cook a chicken depends on the temperature and cooking method used. For example, roasting a 7-pound chicken in the oven at 350 degrees Fahrenheit typically takes between 20 and 30 minutes per pound, or up to 2.5 hours.
Reduce the cooking time for the chicken by increasing the heat. At 425 degrees Fahrenheit, the chicken cooks within 1.5 to 2 hours. When it is fully cooked, the juices should run clear when the skin is pierced. To be more exact, check the internal temperature by inserting an instant-read thermometer in the meatiest part of the breast, where it should be at least 180 degrees Fahrenheit.