A 4-day-old baby typically eats about 1 ounce per feeding, with some babies taking closer to 1.5 ounces as milk supply increases. That works out to roughly 8 to 12 ounces total over 24 hours. The amount sounds tiny, but it matches a newborn’s stomach, which at this age holds only about 22 to 27 milliliters (just under an ounce) at a time.
How Much Per Feeding
Whether you’re breastfeeding or using formula, the target is similar. Breastfed babies take in about 1 ounce per session around days 2 through 4, gradually climbing toward 2 ounces per session by the end of the first week. Formula-fed newborns follow the same pattern: 1 to 2 ounces of formula every 2 to 3 hours in the first days of life, according to the CDC.
Day 4 often falls right in a transition zone. If you’re breastfeeding, your body is shifting from producing colostrum (the thick, yellowish first milk) to making larger volumes of mature milk. This shift typically happens between days 2 and 5, and once it does, you’ll notice your baby swallowing more actively and feeding sessions feeling different. Total daily output for a breastfeeding parent at this stage is around 8 ounces across all feedings combined, rising to 12 to 20 ounces by days 5 through 7.
How Often to Feed
Newborns eat frequently. Expect 8 to 12 feedings in a 24-hour period, which means your baby will want to eat roughly every 2 to 3 hours, including overnight. Some of those feedings will cluster together, especially in the evening, with stretches where your baby wants to eat every hour. That’s normal and actually helps stimulate milk production during the transition from colostrum.
At this age, you should not try to put your baby on a schedule. Feed on demand, every time the baby signals hunger. Watching the clock matters less than watching your baby.
Why the Amounts Seem So Small
A newborn’s stomach at birth is about the size of a hazelnut, holding only 5 to 7 milliliters (roughly a teaspoon). By day 4, it has expanded to about 22 to 27 milliliters, closer to the size of a walnut. That’s why frequent, small feedings are the design rather than the problem. Your baby physically cannot hold much more than an ounce at a time, and overfilling the stomach leads to spitting up.
How to Tell Your Baby Is Getting Enough
Since you can’t measure what a breastfed baby takes in at the breast, diapers are your best tracking tool. The general rule in the early days: expect one wet diaper and one dirty diaper for each day of life. So a 4-day-old should produce at least 4 wet diapers and 4 dirty diapers in 24 hours. By the end of the first week, wet diapers climb to 6 or more per day.
Weight is the other key indicator. It’s normal for newborns to lose up to 7% of their birth weight before starting to gain it back. Most babies hit their lowest weight around day 3 or 4, then begin recovering and return to birth weight by day 10. A loss greater than 10% of birth weight is a warning sign that feeding may need attention. Your pediatrician will check weight at the first office visit, which is usually scheduled within a few days of leaving the hospital.
Hunger and Fullness Cues
Crying is actually a late hunger signal. If you wait until your baby is wailing, they may be too upset to latch or feed well. Earlier cues to watch for include putting hands to mouth, turning the head toward your breast or the bottle (called rooting), smacking or licking lips, and clenching fists. A baby who is doing any of these things is ready to eat.
When your baby has had enough, you’ll see the opposite: their mouth closes, their hands relax and open, and they turn away from the breast or bottle. Some babies fall asleep at the breast when satisfied. Trust these signals rather than trying to push an extra half ounce.
Breastfeeding vs. Formula at This Stage
The volume per feeding is roughly the same for both, but the rhythm can feel different. Breastfed babies tend to eat slightly more often because breast milk digests faster than formula. A formula-fed baby might go a full 3 hours between feedings, while a breastfed baby may want to eat again after 1.5 to 2 hours, particularly during cluster-feeding periods.
If you’re supplementing with formula alongside breastfeeding, keep the supplemental amounts small, around 0.5 to 1 ounce, to avoid overfilling your baby’s stomach and to protect your milk supply. Frequent breastfeeding in these early days is what signals your body to increase production during the colostrum-to-milk transition.
Signs Something May Be Off
A few red flags worth knowing: fewer wet or dirty diapers than expected for the day of life, a baby who is too sleepy to wake for feedings (going longer than 4 hours without eating), weight loss exceeding 10% of birth weight, or a baby who seems hungry immediately after every feeding and never appears satisfied. Dark, concentrated urine or brick-red dust in the diaper after day 3 can also signal that intake is too low. Any of these patterns warrants a call to your pediatrician or a visit with a lactation consultant sooner rather than later.