There is no way of telling right away as to how much of a formula your baby will need; it all depends on your baby’s age and weight. Just like us grownups, a baby’s hunger will vary at different times and from feed to feed. A baby knows when she is hungry and will give you cues like crying and rooting for your nipple or bottle to let you know the same.
The same way, she will give you indications on being full; she will turn her head away or start looking disinterested in the feed. She will also appear playful, happy and relaxed.
The below formula, however, gives you a rough estimate on how much formula feed your baby needs, if you furnish her weight. Please note that this is just a guideline, and approximation, and must not be treated as a thumb rule.