A 4-week-old baby typically drinks 2 to 4 ounces of milk per feeding, eating 8 to 12 times over 24 hours. That works out to roughly 16 to 32 ounces total per day, though every baby is a little different. The exact amount depends on whether your baby is breastfed, formula-fed, or getting a combination of both.
How Much Per Feeding
At four weeks old, your baby’s stomach is about the size of a large chicken egg, holding somewhere between 3 and 5 ounces at a time. Most babies this age take in 2 to 4 ounces per feeding session. Before birth, your baby received constant nutrition through the placenta. Now, their digestive system is still adjusting to taking in food in separate meals rather than a steady stream. That’s why small, frequent feedings work better than fewer, larger ones.
If your baby consistently finishes a bottle and still shows signs of hunger, it’s fine to offer another half ounce or ounce. But pushing past what they want can lead to spit-up and discomfort. Let your baby set the pace.
How Often to Feed
Expect to feed your 4-week-old somewhere between 8 and 12 times in a 24-hour period. For breastfed babies, that often means feeding every 2 to 3 hours, including overnight. Formula-fed babies at this age tend to go a bit longer between feedings, roughly every 3 to 4 hours, because formula takes slightly longer to digest than breast milk.
These numbers are averages. Some babies cluster their feedings, eating several times close together and then sleeping for a longer stretch. This is normal, especially in the evening. It doesn’t mean your milk supply is low or that your baby isn’t getting enough.
Breastfeeding vs. Formula Feeding
If you’re breastfeeding, you can’t measure ounces directly, and you don’t need to. Your baby regulates their own intake at the breast. A typical nursing session at four weeks lasts 10 to 20 minutes per side, though some babies are efficient and finish faster. The key is watching your baby, not the clock.
For formula-fed babies, the numbers are more concrete. Start by offering 2 to 4 ounces per bottle and adjust based on how your baby responds. If they drain the bottle quickly and root around for more, try preparing slightly more next time. If they regularly leave an ounce behind, scale back. Babies who get both breast milk and formula fall somewhere in between, and the same principle applies: follow your baby’s lead.
One nutritional note: babies who are exclusively breastfed, or who receive a mix of breast milk and formula, need a vitamin D supplement starting shortly after birth. Formula contains added vitamin D, so babies drinking only formula typically get enough on their own.
How to Read Your Baby’s Hunger Cues
Rather than feeding strictly by the clock, watch for your baby’s built-in signals. Early hunger cues include licking their lips, sucking on their hands, opening and closing their mouth, and turning their head side to side (called rooting). These are the ideal moments to start a feeding, when your baby is calm and ready to eat.
If those early signs are missed, babies escalate. They’ll start bobbing their head, fussing, and moving their head frantically from side to side. By the time a baby is full-on crying with agitated body movements, they’re past hungry and into upset territory. A very worked-up baby often needs to be calmed down before they can latch or take a bottle well.
Fullness cues are just as important. A satisfied baby will slow their sucking, turn away from the breast or bottle, relax their hands, or fall asleep. If your baby pulls off the breast on their own or stops sucking on the bottle nipple, the feeding is done. There’s no need to coax them into finishing a specific amount.
Signs Your Baby Is Getting Enough
Since you can’t always measure exactly how much milk goes in, especially with breastfeeding, diaper output and weight gain are the two most reliable indicators that your baby is well-fed.
By four weeks, your baby should produce at least 6 wet diapers per day. The number of dirty diapers varies more widely, especially between breastfed and formula-fed babies, but consistent wet diapers are the clearest day-to-day sign of adequate hydration.
Weight gain is the longer-term measure. In the first few months, babies gain about 1 ounce per day, or roughly 5 to 7 ounces per week. Your pediatrician will track this at regular checkups. Steady weight gain along your baby’s growth curve, even if they’re on the smaller side overall, is more important than hitting a specific number on the scale.
Warning Signs of Underfeeding
Occasionally, a baby doesn’t get enough milk. This can happen for several reasons: trouble latching, a low milk supply, or a baby who is too sleepy to eat enough. The signs to watch for include fewer than 6 wet diapers a day, a sunken soft spot on top of the head, sunken eyes, few or no tears when crying, and unusual drowsiness or irritability. A baby who seems increasingly difficult to wake for feedings or who is losing weight needs prompt medical attention.
If you notice any of these signs, or if your baby has gone significantly longer than 4 hours without showing interest in eating, contact your pediatrician. Dehydration in a newborn can progress quickly, but it’s also very treatable when caught early.