A 4-day-old baby typically eats 1 to 2 ounces (30 to 60 ml) per feeding, every 2 to 3 hours. That adds up to roughly 8 to 12 feedings in a 24-hour period. The exact amount varies depending on whether your baby is breastfed or formula-fed, and individual babies have slightly different appetites even at this age.
Stomach Size at Four Days
A newborn’s stomach is tiny. Between days 3 and 6, it’s roughly the size of a grape, holding about 30 to 60 ml (1 to 2 ounces) at a time. This is why newborns eat so frequently. They physically can’t take in very much at once, so they need to refuel often. Trying to push more than this amount in a single feeding can lead to spitting up or discomfort.
Breastfed vs. Formula-Fed Amounts
If your baby is breastfed, you won’t be measuring ounces, and that’s completely normal. Breastfed babies regulate their own intake at the breast, and the goal is simply to feed on demand, which at 4 days old means every 1 to 3 hours. Most breastfed newborns nurse 8 to 12 times per 24 hours. Some cluster their feeds, eating several times in a short stretch and then sleeping a longer period.
Day 4 also falls right in the middle of a major transition in your milk. For the first couple of days after birth, your breasts produce colostrum, a thick, concentrated early milk that comes in very small volumes. Between days 2 and 5, transitional milk starts coming in, gradually increasing in volume. Many parents notice their breasts feeling fuller around this time, and their baby starting to take longer, more satisfying feeds. This transition continues for about two weeks until mature milk is fully established.
For formula-fed babies, the CDC recommends starting with 1 to 2 ounces of formula every 2 to 3 hours in the first days of life. Let your baby guide the pace. If they finish a bottle and still show hunger cues, it’s fine to offer a small amount more. If they turn away or close their mouth partway through, they’ve had enough.
How to Tell Your Baby Is Hungry
Crying is actually a late sign of hunger. Well before that point, a hungry newborn will put their hands to their mouth, turn their head toward your breast or the bottle (called rooting), pucker or smack their lips, or clench their fists. Catching these early cues makes feeding easier because a calm baby latches and eats more effectively than one who’s already upset.
When your baby is full, the signals flip. They’ll close their mouth, turn their head away from the breast or bottle, and relax their hands. These are reliable cues at any age, but they’re especially useful in the first week when you’re still learning your baby’s rhythms.
Diaper Output as a Feeding Check
Since you can’t measure how much a breastfed baby takes in, diapers are your best window into whether they’re getting enough. The general pattern in the first few days is simple: a baby typically produces about one wet diaper and one dirty diaper for each day of life. So on day 4, you’d expect around 4 wet diapers and 4 dirty diapers.
This number climbs quickly. By the end of the first week, most well-fed newborns produce 6 or more wet diapers a day. If your baby is consistently falling short of these numbers, it’s worth checking in with your pediatrician or a lactation consultant.
Normal Weight Loss in the First Week
Almost all newborns lose weight in the first few days after birth. This is expected and not a sign that feeding is going wrong. The concern point is when weight loss exceeds 10 percent of birth weight. So if your baby was born at 7 pounds 8 ounces (3,400 grams), losing more than about 12 ounces (340 grams) by day 4 or 5 would warrant a closer look at feeding.
Most babies hit their lowest weight around days 3 to 4 and then start gaining. By about two weeks, they should be back to their birth weight. Your baby’s doctor will track this at early checkups, but knowing the 10 percent threshold helps you understand what they’re looking for.
Signs Your Baby Isn’t Getting Enough
Beyond diaper counts and weight, there are physical signs that a 4-day-old may be underfed or dehydrated. Watch for a sunken soft spot on top of the head, sunken eyes, few or no tears when crying, drowsiness that makes it hard to wake them for feeds, or unusual irritability. Any of these warrants a prompt call to your baby’s doctor.
Mild jaundice (a yellowish tint to the skin) is also common around day 3 to 5 and can worsen if a baby isn’t eating enough, since frequent feeding helps flush out the bilirubin that causes it. Feeding on schedule, or more often, is one of the most effective ways to help mild jaundice resolve.
Feeding at Night
At 4 days old, your baby needs to eat overnight. Most pediatricians recommend not letting a newborn go longer than 3 to 4 hours without a feeding, even if that means waking them. Their small stomach and high caloric needs relative to body size mean that long stretches without food can lead to low blood sugar or excessive weight loss. This changes as babies grow, but in the first week or two, round-the-clock feeding is the norm.