A 4-week-old typically drinks 3 to 4 ounces of formula per feeding, every 3 to 4 hours, totaling roughly 24 to 32 ounces over a full day. That said, every baby is slightly different, and the right amount depends more on your baby’s hunger cues and weight gain than on hitting an exact number.
How Much Per Feeding
By the end of the first month, most formula-fed babies have worked up to 3 to 4 ounces (90 to 120 ml) per bottle. Earlier in the month they may still be closer to 2 to 3 ounces, so if your baby just turned 4 weeks and isn’t quite finishing a 4-ounce bottle, that’s normal. Babies gradually increase their intake over the first several weeks of life rather than jumping to a set amount overnight.
A simple way to think about it: your baby’s stomach at birth was roughly the size of a marble, holding just 1 to 2 teaspoons. By day 10 it had grown to the size of a ping-pong ball, holding about 2 ounces. At 4 weeks, that stomach is still small. Offering 3 to 4 ounces and letting your baby decide when to stop is a better strategy than trying to push a set volume.
Daily Total and Feeding Frequency
Most 4-week-olds eat about 6 to 8 times in a 24-hour period, spacing feedings roughly every 3 to 4 hours. That puts the daily total somewhere between 18 and 32 ounces, depending on the size of each feeding. The general upper limit to keep in mind is about 32 ounces (960 ml) per day. Consistently exceeding that is worth mentioning to your pediatrician.
Night feedings are still very much part of the picture at this age. A 4-week-old’s stomach empties quickly, so going longer than 4 to 5 hours without eating overnight is uncommon. If your baby sleeps a longer stretch, you don’t necessarily need to wake them for a feeding as long as they’re gaining weight well and making enough wet diapers.
Reading Your Baby’s Hunger and Fullness Cues
Charts and ounce ranges are useful starting points, but your baby gives real-time feedback that matters more than any guideline. Learning to read those signals helps you avoid both underfeeding and overfeeding.
Signs your baby is hungry include putting hands to their mouth, turning their head toward the bottle (called rooting), lip smacking or licking, and clenched fists. Crying is actually a late hunger cue. If you can catch the earlier signals, feedings tend to go more smoothly.
Signs your baby is full include closing their mouth, turning their head away from the bottle, and visibly relaxing their hands. When you see these, it’s fine to stop the feeding even if there’s formula left in the bottle. Trying to get a baby to finish every last drop can lead to overfeeding and discomfort.
Growth Spurts Change the Pattern
Around 2 to 3 weeks, many babies go through their first growth spurt, and another one commonly hits around 6 weeks. That means your 4-week-old may be coming off one spurt or ramping up toward the next. During a growth spurt, babies become fussier and hungrier than usual, sometimes wanting to eat every 2 hours instead of every 3 to 4.
This is normal and temporary, typically lasting a few days. The best response is simply to offer extra feedings when your baby seems hungry rather than trying to stick rigidly to a schedule. Once the spurt passes, your baby will likely settle back into a more predictable routine, often at a slightly higher baseline intake than before.
How to Tell Your Baby Is Getting Enough
The most reliable day-to-day sign that your baby is eating enough is diaper output. After the first week of life, you should see at least 6 wet diapers per day. The number of dirty diapers varies more from baby to baby, but consistent wet diapers mean your baby is well hydrated.
Weight gain is the other key measure, and your pediatrician tracks this at well-child visits. Most newborns gain about 5 to 7 ounces per week during the first month. If your baby is steadily gaining weight and producing plenty of wet diapers, the exact ounce count at each feeding matters less than the overall trend.
One Important Safety Note on Preparation
If you’re ever tempted to stretch formula by adding extra water, don’t. Over-diluting formula reduces the concentration of calories and nutrients your baby receives, which can lead to poor growth. In more serious cases, too much water relative to formula can dilute the sodium in your baby’s blood to dangerous levels. Always follow the mixing instructions on the label exactly as written, using the scoop that comes with that specific formula.