My 5 week old is exclusively formula fed. I vaguely remember something about the amount they need being based on their weight...there was a calculation I saw somewhere... Anyway we have been going by the guide on the tin which is by age and our boy seems to want a lot more. He has been a large baby since birth 9lb13 so I was wondering maybe it's normal for him to have more??? My first was exclusively breastfed for 13 months so this formula stuff is all new to me.... Any advice would be great... We go by his hungry signs as to when we feed him.... And sometimes he finishes a bottle sometimes he doesn't.