Ounces to Weight Ratio
A general rule of thumb is that a baby should consume 2 to 3 ounce of formula per day for every pound of body weight. So an 18-pound 7-month-old baby should receive about 36 ounces of formula per day. More if she is not yet eating solid food. Breastfed babies should wet 4 to 6 diapers everyday, indicating they are getting enough milk.
Solid Foods
Babies start to experiment with solid foods between 4 and 6 months and begin to eat them at every meal after 6 months, depending on the interest of the baby. A 7-month-old who is eating cereals, fruits and veggies at every meal may decrease the amount of formula she drinks, but increase the amount of water. A 7-month-old should always have the appropriate amount of formula per her weight available to her each day.
Bottom Line
A 7-month-old baby who is gaining weight consistently, eating and drinking well, wetting 4 to 6 diapers a day and having a bowel movement once or twice a day is likely getting enough formula to drink. Check with your doctor if you have concerns.