A 5-day-old baby eats roughly 22 to 27 milliliters (about 1 ounce) per feeding if breastfed, and 1 to 2 ounces per feeding if formula-fed. That sounds tiny, but it matches the size of your baby’s stomach, which at five days old is only about as big as a walnut. Feedings happen frequently at this age, typically 8 to 12 times in a 24-hour period, so the small amounts add up.
Stomach Size Sets the Limit
At birth, a newborn’s stomach holds only about 5 to 7 milliliters, roughly the size of a hazelnut. By day 3 to 5, that capacity grows to 22 to 27 milliliters, which is just under one ounce. This is why newborns need to eat so often. They physically cannot take in large volumes at once, so they make up for it with frequent, small meals spread across the day and night.
Breastfeeding Amounts and Timing
If you’re breastfeeding, measuring exact ounces isn’t practical or necessary. Instead, the key numbers to watch are frequency and duration. Breastfed newborns typically nurse every 2 hours, counting from the start of one feeding to the start of the next. That works out to 10 to 12 nursing sessions in 24 hours. Each session can last up to 20 minutes or longer on one or both breasts.
At five days, your mature milk is starting to come in (or may have already), replacing the thick, yellowish colostrum your baby has been getting since birth. As your milk supply increases, your baby will start getting more volume per feeding. If your milk production is delayed, your baby may want to nurse more frequently to compensate. This is normal and actually helps stimulate your supply.
Formula Feeding Amounts and Timing
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. At five days old, most babies are still in this range. That means roughly 8 or more feedings per 24 hours as a minimum. Some babies will consistently take 1 ounce, others will take closer to 2. Let your baby guide you rather than pushing them to finish a set amount.
Hunger and Fullness Cues to Watch For
Your baby will tell you when they’re hungry before they start crying. Early hunger cues include putting hands to their mouth, turning their head toward your breast or the bottle (called rooting), puckering or smacking their lips, and clenching their fists. Crying is actually a late sign of hunger, so try to catch the earlier signals when you can. A calm baby latches and feeds more effectively than a frantic one.
When your baby is full, they’ll close their mouth, turn their head away from the breast or bottle, and visibly relax their hands. These signals are your best guide to how much is enough. Trying to force extra milk after your baby shows fullness cues isn’t helpful.
Cluster Feeding Around Day 5
Don’t be alarmed if your baby suddenly wants to eat every hour or even more frequently. This pattern, called cluster feeding, is common in the first week. It can feel like your baby is never satisfied, but it doesn’t necessarily mean your supply is low. Cluster feeding helps signal your body to produce more milk as your baby’s needs grow.
That said, if your baby is cluster feeding around the clock by day 5 with no breaks, it could be a sign they aren’t getting enough at each feeding. By the end of the first week, the constant cluster feeding pattern should start to ease. If it doesn’t, a lactation consultant or your baby’s pediatrician can check whether the latch is effective and your baby is transferring milk well.
How to Tell Your Baby Is Getting Enough
Since you can’t measure what a breastfed baby takes in, diaper output is the most reliable indicator. By day 5, your baby should be producing at least 6 wet diapers per day. The number of dirty diapers will vary, but you should be seeing some. Fewer wet diapers than this can signal dehydration.
Weight is the other key measure. Most newborns lose some weight in the first few days after birth, which is completely expected. The concern threshold is a loss of 10 percent or more of birth weight, which warrants a careful assessment. Most babies begin regaining weight between days 3 and 5, and about 80 percent are back to their birth weight by two weeks. Your baby’s pediatrician will track this at early checkups, so those first appointments matter.
Breastfed vs. Formula-Fed: Key Differences
- Frequency: Breastfed babies typically eat more often (every 2 hours, or 10 to 12 times daily) because breast milk digests faster than formula. Formula-fed babies eat every 2 to 3 hours, with a minimum of about 8 feedings daily.
- Volume per feeding: Formula-fed babies may take slightly more per session (up to 2 ounces) since formula is delivered at a consistent flow. Breastfed babies regulate their own pace, and intake varies from feeding to feeding.
- Tracking: With formula, you can see exactly how much your baby drank. With breastfeeding, you rely on feeding duration, diaper counts, and weight checks to confirm adequate intake.
Both feeding methods provide complete nutrition at this age. What matters most is that your baby is eating frequently enough, producing enough wet diapers, and starting to regain weight by the end of the first week.