Typically, most newborns (2-3-week-old baby) that are formula-fed or breast-fed should be fed every 2 to 3 hours. As they grow older and their tummies can comparatively hold more milk, they usually start consuming it every 3 to 4 hours.
And if the baby is very young, or is facing problems gaining weight, you should never go too long without feeding, even if it requires waking your baby. In such a condition, seek your doctor's help, talk to him about how often your baby should be fed. It is important to feed baby with proper diet so that they can grow well.
This is the most common question for every new parents. Most of the newborn babies eat(half ounce per feeding) in every 2 to 3 hours in a day. This can be increase to 2 to 3 ounces as they grow by 2-3 week. Then 4 to 6 ounces per feeding at age of 4 months in every 3-4 hours.