How Much Do Newborns Eat, Really? We Asked a Pediatrician

Of the many questions new parents will find themselves asking, the ones that have to do with how much a newborn eats can often feel especially urgent – and confusing. After all, whether you’re breastfeeding or using formula, how much newborns eat changes a lot in the first few days and weeks of your little one’s life. And so do factors like their weight, which you might normally use as signs of underfeeding or overfeeding.

The short answer is that how much newborns eat varies depending on the baby. But there are some general rules of thumb about roughly how many fluid ounces they should be consuming during each feeding, and how often they should be eating. Here, pediatricians lay out how much your newborn may eat during the day, how frequently you should feed them, how to know if your baby isn’t eating enough or is eating too much, and when it’s time to talk to a pediatrician.

How Much Does a Newborn Eat?

Newborn babies’ stomachs are no bigger than a toy marble at birth, according to Women, Infant and Children (WIC) Breastfeeding Support. So at each feeding, they’ll consume about one to two ounces of breastmilk or formula, says Emily Wisniewski, MD, a board-certified pediatrician at Mercy Medical Center in Baltimore, Maryland.

But those tiny stomachs empty quickly too, so newborn babies should be eating every two to three hours, or about eight to 12 times per 24 hours, according to the American Academy of Pediatrics.

“As they continue to grow, this will for sure change,” Dr. Wisniewski says. As early as 2 to 3 weeks, they may begin to eat more frequently – every hour or less, especially in the evenings. This is what’s known as cluster feeding, and while it can be exhausting for parents, it’s normal, and often a sign of an impending growth spurt.

When your baby is about 4 months old, they’ll be consuming four to six ounces of breastmilk or formula at a time, and they may even be ready for the introduction of solids, she says. At 6 months old, they’ll be up to six ounces of food plus solids, and at 9 months, they’ll take six to eight ounces per feeding – but they may only be eating four or five times per day, because by that point “they’re eating so many more solids,” Dr. Wisniewski says.

How To Know If Your Newborn Is Eating Enough

If you’re pumping breast milk or using formula, you can measure how much you’re putting into each bottle and how much your baby actually consumes. But if you’re breastfeeding, it’s difficult to tell exactly how much breast milk your baby is consuming at a time.

One way you can get a rough estimate is if you weigh your baby before and after a feeding, Dr. Wisniewski says. The difference in ounces is the amount of breast milk your baby took in.

Additionally, the breastfeeding parent “should be able to hear the infant swallowing, and [their] breasts should feel like they’re emptying. The infant should also not be showing signs of hunger after feeding,” Dr. Wisniewski says.

But that last one can be a little less reliable than others, since sometimes breastfed infants want to nurse for comfort, even when they’re not hungry, she adds.

Other markers to keep an eye on include “good urine output and stools and weight gain,” Dr. Wisniewski says. According to the AAP, newborn babies usually have two to three wet diapers daily a few days after birth. Once they’re about 5 days old, newborns produce five to six wet diapers daily.

The number of times a newborn poops varies whether they are breastfed or formula fed. For the first five days of life, breastfed babies poop about as many days as they are old (so one poop on when they’re 1 day old, two when they’re 2 days, etc.), according to What To Expect. After that, several poopy diapers a day is normal, though they’ll decrease again around 6 weeks. Formula-fed babies poop about three to four times a day.

How to Know If Your Newborn Isn’t Eating Enough

Red flags that your baby isn’t taking in enough breast milk or formula is if their urination and poop output decreases and they’re losing weight, Dr. Wisniewski says. They may also be more irritable and cranky. “If you are seeing these things, you should follow up with your pediatrician to get a weight. The weight is the best way to tell what’s going on,” she says.

At the appointment, your pediatrician will weigh your baby and see if it aligns with their growth chart. Newborns who are eating enough during their feedings will follow a steady growth rate.

Can You Overfeed a Baby?

Overfeeding is less of a concern, because babies tend to turn away from the breast or bottle when they’re full. If you’re concerned you may be overfeeding your baby, it’s best to talk to your pediatrician. You can’t tell just based on their size or how often they’re feeding (remember, cluster feeding is a common occurrence.) And while spitting up can be a sign of overfeeding, it can also be a normal infant reaction, so it’s not a reliable red flag either. Bottom line: talk to a doctor before ever cutting back on an infant’s feeding schedule.

Should I Wake Up My Baby To Eat?

Right after delivery, newborns shouldn’t go longer than four to five hours without a feeding. As they get older, around 3 to 4 weeks, you can extend the length of time between feedings to every six hours, Dr. Wisniewski says. But that doesn’t mean you’ll have to wake them up in order to eat.

“Provided the infant is growing normally with normal urination and stooling, they tend to fall asleep when they are full. You don’t have to fight an infant or wake them to make sure they get enough; because it’s also possible that they feed a little less this time, but more the next time,” Dr. Wisniewski says.

That says, defer to your doctor’s advice. Right after delivery, especially if your newborn is premature or has a heart defect, they may suggest waking them on a set schedule (if they don’t rouse themselves) to make sure they’re getting enough nutrients.