It depends on various factors such as the size of the chicken, the cooking method, and the desired level of doneness. Generally, a chicken needs to be cooked for around 20 minutes per pound at 350 degrees Fahrenheit (175 degrees Celsius) until it reaches an internal temperature of 165 degrees Fahrenheit (75 degrees Celsius). However, it is always best to use a meat thermometer to ensure that the chicken is fully cooked.