My 3 month old baby slept through nyt (6 hrs) is it ok to feed on demand?

A. A 3-month-old needs to eat about 4 to 6 ounces of breast milk or formula every 3 to 4 hours. 1 Since all babies are different, some babies will eat a little more or a bit less than this. When your baby is 3 months old, they have reached an important milestone—they are no longer considered a newborn.