Depending on how much your baby is drinking in a single feeding:
2 oz. or 60ml of water: 1 scoop of formula
3oz. or 90ml of water: 1&1/2 scoops of formula
4oz. or 120ml of water: 2 scoops of formula
5oz. or 150ml of water: 2&1/2 scoops of formula
Remember to have even and level scoops of formula powder to make sure you are adding the correct amount.