I buy organic free-range chicken when possible. And yet, you can buy a standard roast chicken at any supermarket. Also, it's best to buy a medium-size, not too small and not too large. A small chicken is about 1.2 kgs or 2.5 pounds and would feed 2 to 3 people. While a medium-size is 1.75 to 2 kgs (3.5 to 4 pounds) and will feed about 4 to 6 people. Also, leftovers from a roast chicken are always a good thing to have. So, a slightly bigger chicken than you need is not a bad idea.