A 4-week-old baby typically eats 3 to 4 ounces per feeding, about 8 to 12 times in a 24-hour period. That works out to roughly 24 to 32 ounces of breast milk or formula per day, though every baby is different. If your baby was eating smaller amounts in the first couple of weeks, this increase is normal and expected.
How Much Per Feeding
By the end of the first month, most babies take at least 3 to 4 ounces (90 to 120 mL) per feeding session. This is a gradual increase from the early days of life, when a newborn’s stomach is only about the size of a marble and can hold just 1 to 2 teaspoons. By day 10, the stomach has grown to roughly the size of a ping-pong ball (about 2 ounces), and it continues expanding from there.
At 4 weeks, some babies may still be closer to 3 ounces per session, while hungrier or larger babies might take a full 4 ounces. Both are within the normal range. What matters more than hitting an exact number is whether your baby seems satisfied after a feeding and is gaining weight steadily.
Breastfed vs. Formula-Fed Babies
Breastfed and formula-fed babies eat on slightly different patterns, even if the total daily intake ends up similar. Formula-fed newborns typically settle into a rhythm of feeding every 3 to 4 hours by this age, which usually means 8 or so feedings per day. Breastfed babies tend to eat more frequently, every 2 to 4 hours, because breast milk digests faster than formula. That can mean 8 to 12 nursing sessions in 24 hours.
If you’re breastfeeding, you can’t see exactly how many ounces your baby is taking per session. Instead of measuring volume, you rely on other signals: your baby seeming content after a feeding, consistent weight gain at checkups, and adequate diaper output. After the first five days of life, a well-fed baby should produce at least 6 wet diapers per day. The number of soiled diapers varies more widely but is another useful indicator.
The Growth Spurt Factor
Right around this age, your baby may suddenly seem insatiable. Growth spurts commonly happen at 2 to 3 weeks and again at 6 weeks, so a 4-week-old can fall right in between these periods of increased demand. During a growth spurt, babies want to eat longer and more often, sometimes as frequently as every 30 minutes. It can feel like feeding is all you do.
This is temporary, usually lasting a few days. For breastfeeding parents, the frequent nursing serves a specific purpose: it signals your body to produce more milk to keep up with your baby’s growing needs. For formula-fed babies, you may notice your baby draining bottles faster or acting hungry sooner than usual. Offering an extra ounce per bottle during these stretches is reasonable, but let your baby’s cues guide you rather than forcing a set amount.
Reading Your Baby’s Hunger Cues
Feeding on demand, rather than on a strict schedule, is the standard recommendation at this age. Your baby will tell you when they’re hungry before they start crying. Early hunger cues include putting hands to the mouth, turning their head toward the breast or bottle (called rooting), smacking or licking their lips, and clenching their fists. Crying is actually a late hunger signal, so catching the earlier signs makes feedings smoother for both of you.
Fullness cues are just as important. A baby who is done eating will close their mouth, turn their head away from the breast or bottle, and relax their hands. If your baby is showing these signs, don’t push them to finish the last half ounce in the bottle. Overfeeding can cause discomfort and spitting up, and respecting fullness cues early on helps your baby develop healthy self-regulation around eating.
Signs Your Baby Is Getting Enough
The simplest day-to-day check is diaper count. After the first five days, your baby should have at least 6 wet diapers every 24 hours. Fewer than that can signal dehydration or insufficient intake. Weight gain is the other key measure, and your pediatrician will track this at regular checkups. Most babies regain their birth weight by about 2 weeks of age and then gain roughly 5 to 7 ounces per week through the first few months.
Other reassuring signs include your baby seeming alert and active during awake periods, having good skin color, and being generally content (not constantly fussy) between feedings. If your baby is consistently eating less than 3 ounces per feeding, seems lethargic, or is producing fewer wet diapers than expected, that’s worth bringing up with your pediatrician sooner rather than later.
What to Expect in the Coming Weeks
Feeding amounts increase steadily over the next couple of months. By 2 months, many babies are taking 4 to 5 ounces per feeding. The frequency of feedings gradually decreases as the volume per session goes up, so you’ll likely shift from 8 to 12 feedings per day down to 6 to 8 by the time your baby is 2 to 3 months old. Most formula-fed babies plateau at around 32 ounces per day, and babies who reach that amount consistently don’t need a vitamin D supplement beyond what’s in the formula. Breastfed babies, regardless of volume, typically do need a separate vitamin D supplement.