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How Breast Milk Feeding Amounts Vary by Age

Leana L. Thompson, RN, BSN, IBCLC

An IBCLC Looks at a Baby’s First Year

A primary reason that I’m a practicing International Board Certified Lactation Consultant (IBCLC) is to help parents understand what to expect during the first year of their feeding journeys with their infants.

Having access to guideposts—like how much breast milk or formula a baby is expected to consume at each feeding, across their first year of life—can help alleviate parental anxiety in a time of so many other unknowns.

What to Expect in the First 2 Weeks

When a baby is born, their stomach is the size of a cherry. The average feeding for a 1-day-old infant is about 1 teaspoon of either breast milk or formula. That’s it! Though that amount may seem so tiny, your colostrum—the first, nutrient-dense form of breast milk, which birth parents produce in the first few days after delivery—is the perfect amount to feed your baby.

Still, many breastfeeding parents fear they are not producing enough breast milk for their baby in the first two weeks. That’s why sharing education with parents about the size of babies’ bellies during the first two weeks is so important. We IBCLCs aim to alleviate some of those parental anxieties.

During these first weeks, babies often “cluster feed”—wanting multiple, short feedings over the course of a few hours. Cluster feeding at the breast brings lots of stimulation to help your milk transition from colostrum to that transitional milk which then becomes your mature breast milk.

By day three, your baby’s belly is growing to the size of a ping pong ball. Your baby now is taking in about 1 ounce during a feeding, whether it’s breast milk or formula. By the end of the first two weeks, your baby’s belly will be the size of an egg. At 2 weeks old, your baby can tolerate about 2-3 ounces per feeding. (Note: these numbers are averages, and each baby is different.)

What to Expect From 2 Weeks to 6

If you’re providing breast milk for your baby, weeks two through six of your baby’s life are a crucial time for establishing your supply. If you have not met with a lactation consultant yet, this is a good chance to check in with one. These IBCLCs can help you understand if your baby is transferring milk from your breasts efficiently, and that your milk supply is where you want it to be. Whether it’s breast milk or formula, an average feeding during these weeks is 2-4 ounces. If you are pumping and replacing a breastfeeding session with the pumped milk, an IBCLC would expect you to pump a total of 2-4 ounces. If you just nursed a baby and you are pumping after a feeding, the average amount of pumped milk is 0.5-2 ounces. If you make anything over 5 ounces during a post-feed pump session, that could be considered as a slight over-supply (and another topic to discuss with your lactation consultant).

As long as your feeding routine works for you and your baby, and you are not having any issues with clogged ducts or recurrent mastitis, then you should be okay. Reach out to an IBCLC if you need help increasing or stabilizing your supply.

Remember, during these weeks, supply and demand is crucial. The more you nurse or pump on demand, the more milk you make. Your postpartum hormones in the first six weeks are high, and it’s easier to increase your milk supply during this time, compared to after this six-week window. This period is the crucial time to introduce a bottle to your exclusively breastfed baby.

What to Expect From 6 Weeks to 6 Months

At six weeks after delivering a baby, your hormones start to plateau. Commonly, breastfeeding parents feel like their milk supply is decreasing during this time. In reality, their body has finally figured out the perfect precise amount of breast milk for their baby’s needs. This is when your body starts to make a consistent amount of milk.

If you suspect you are seeing a dip in milk supply during this time, you can reach out to an IBCLC for an assessment. Usually, breastfeeding starts to take less time than bottle feeding, since baby is becoming more efficient at removing milk from the breast during feeds.

Babies’ breast milk consumption per feeding typically becomes consistent during this time period. Whether they are six weeks old or six months old, they will need about 2-5 ounces per feeding. The volume range depends on when they last fed. If they’re getting a bottle, the guideline is between 1 ounce and 1.5 ounces per hour from when they last fed. So, if a baby is eating every three hours during the day, you would prepare a bottle of breast milk that’s between 3 ounces and 4.5 ounces for them.

Around age 2-to-4-months, formula feeders usually start consuming 4-to-6 ounces every four hours. This generally holds steady until they’re about 6 months old.

What to Expect From 6 Months to One Years Old

Starting at age 6 months, the game changes because this generally is the time when babies start to eat solid foods. We IBCLCs recommended to still offer breast milk or formula before offering solids at feedings. Both liquid options are still their primary source of nutrition until they’re 12 months old. Older babies are faster feeders and may get distracted very easily, so we want to get their primary nutrition in, first.

During this stage, babies usually still only need 3-5 ounces per feeding of breast milk. If your baby is on formula during this stage, the average formula feeding bottle is 6 to 8 ounces, with no more than 36 ounces in a 24-hour period.

The reason why this differs from breast milk volume is because the calories per ounce will vary with breast milk, since breast milk changes in water and fat composition to meet baby’s developing nutritional needs. Formula’s nutritional content is consistent, so a growing baby needs more formula volume to meet their increasing nutritional needs.

If you are struggling with maintaining your milk supply at any stage, remember to reach out to an IBCLC. We are on your team and always happy to help you reach your feeding goals.

About the author:

Leana L. Thompson, RN, BSN, IBCLC

Leana is a Registered Nurse, an International Board Certified Lactation Consultant, and a mom of two little girls under age 2. She lives in Gilbert, Arizona, where she owns her own business, LactationNow. She worked as a Mother-Baby RN for nearly a decade in hospitals all across the United States. Leana offers in-home and virtual lactation consultations. LactationNow’s goal is to provide services that give you and your partner the ultimate mother-baby experience before and after you leave the hospital. She covers prenatal breast consults, weaning consults, and everything in between. She also shares pumping and breastfeeding tips and tricks on her social media (@lactationnow) to support families across the globe. Contact Leana at for virtual or in person IBCLC support.

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