Tracking your baby’s weight can be a helpful marker of healthy growth and development. But know that when it comes to your baby’s weight in the first year, there’s a big range of normal. Babies can be healthy at the 5th, 50th percentile or 95th percentiles. In other words, healthy babies come in all sizes. 

Your child’s pediatrician will measure your baby’s weight at every well check, but along with that metric, they’ll also track their length and head circumference, plus how they’re progressing on their developmental milestones. Most important? They’ll measure your baby’s growth over time, looking at the overall growth curve throughout that first year to monitor a child’s growth patterns, detect any deviations from the norm, and provide necessary interventions or support to optimize their health and well-being. If you’re curious about your baby’s average weight by month, our reference guide below can be a helpful tool. And because feeding and sleep patterns also play into healthy growth, we’ll touch on what you need to know there, too.

Editor’s note: If you have any concerns about your baby’s health or growth, reach out to your child’s pediatrician.

Average baby weight at 1 month

During the first month of life, your little love will undergo some pretty remarkable changes. Newborns typically lose a small amount of their birth weight in their first week, but they quickly regain it (thanks to feeding around the clock) and then should continue to gain weight steadily. On average, infants gain about an ounce per day during the first month. 

According to the WHO and CDC: 

Feeding and nutrition

Is your baby hungry *all* the time? It might seem that way. Though baby’s stomach is still small, it’s growing every day. In the first month, babies usually drink breast milk every 2 to 3 hours or formula every 3 to 4 hours—but in these early months, it’s important to follow your baby’s hunger cues and feed on demand.

Sleep patterns

Keep in mind that your 1-month-old’s sleep shouldn’t follow a true schedule just yet. Pay attention to their sleepy cues (like rubbing their eyes, fussiness, staring off into space) and wake windows, which will help prevent them from getting overtired. And if you’re holding them for naps (aka contact napping)? That’s definitely OK.

Related: 1-month-old baby health & growth guide

Factors affecting baby weight

There are several factors that contribute to how much your baby weighs, including:

    • Size at birth: The weight of your baby at birth may influence their weight in the first year.

    • Assigned sex at birth: Males tend to weigh a bit more than females, and tend to gain weight slightly faster.

    • Gestational age: Babies born preterm or early full term may weigh less than babies born full or late-term.

    • How they’re fed: Breastfed babies may gain weight slightly faster than formula-fed babies in the first 6 months of life, according to AAP.

Average baby weight in months 2 and 3

As your baby enters the second and third months, their rapid growth continues. Cognitive and motor skills are developing at a quick clip, too. Your little love is becoming more responsive to their surroundings, can use their hands more, recognizes familiar faces, and may even coo and smile (swoon!). In months 2 and 3, your baby may gain an average of 5 to 7 ounces per week. 

Read below for the average weight according to the WHO and CDC.

Average weight at 2 months

Related: 2-month-old baby health & growth guide

Average weight at 3 months

  • A 3-month-old baby boy in the 50th percentile weighs 14 pounds (6.4 kilograms).
  • A 3-month-old baby girl in the 50th percentile weighs 12 pounds, 14 ounces (5.8 kilograms)

Related: 3-month-old baby health & growth guide

Feeding and nutrition

Though your 8-week-old baby’s feeding schedule might be getting a bit more organized, as in, you can better predict when they might be getting hungry, don’t aim to set any strict schedules just yet. You might also see your infant experience a growth spurt or two during this timeframe. These periods are characterized by sudden and rapid growth, increased appetite, and more frequent feeding, also known as cluster feeding. You might also notice more night wakings and fussiness, but trust that growth spurts rarely last more than a week.

Sleep patterns

Your 2-month-old is still considered a newborn, which means they’ll still be sleeping most of the day. But their wake windows might be stretching out slightly, and by 3 months, night sleep may be consolidating a little more. Note that your 3-month-old’s sleep shouldn’t follow a true schedule quite yet—that will come closer to month 4. Still, aim for 3 to 5 naps per day. 

Factors affecting baby length

There are several factors that contribute to your baby’s length and future height:

  • Parental height: The height of a baby’s parents and other family members strongly influences their future height.

  • Nutrition: Adequate nutrition during pregnancy and after birth can lead to strong bones and muscles.

  • Overall health: Chronic disease during childhood can affect future growth and development.

  • Assigned sex at birth: Males tend to be slightly taller than females.

Average baby weight in months 4, 5, and 6

In months 4 through 6, your baby will start to become even more curious and eager to explore their surroundings. These months are big for motor development—they may start to roll over, gain better head and neck control and start to sit with support. By 4 or 5 months, many babies will have doubled their birth weight. You can expect your little one may gain another 1 pound to 1.25 pounds in months 4 and 5, but growth will start to slow down after the 6-month mark (though only slightly!). Also at 6 months? Starting solids! Consult with your pediatrician to ensure a smooth transition to solid foods.

Read on for the average weight according to the WHO and CDC.

Average weight at 4 months

Related: 4-month-old baby health & growth guide

Average weight at 5 months

Related: 5-month-old baby health & growth guide

Average weight at 6 months

Related: 6-month-old baby health & growth guide

Feeding and nutrition

Through the first year of life, until age 1, breast milk or formula should be your baby’s primary source of nutrients and calories. When they start to eat solid foods around the 6-month mark, your goal will be to help them explore new tastes and textures—while still ensuring they get their nutrition from breast milk or formula to foster healthy growth. 

As an example, the AAP and La Leche League (LLL) recommend the following feeding timeline and amounts for 5-month-olds:

  • Breast milk: 5 to 7 ounces every 3 to 4 hours
  • Formula: 5 to 6 ounces every 4 to 5 hours

Sleep patterns

At this time, your baby’s wake windows are stretching out even more, which means more time for play, outdoor walks and tummy time. Though you should still be aiming for a total of 12 to 16 hours of sleep per 24 hours, with around 10 to 12 hours of consolidated night sleep, according to the American Academy of Sleep Medicine. 

Your infant may wake more often at night or have trouble settling down for sleep around now thanks to the dreaded 4-month sleep regression, but reframing the regression as a progression can hopefully help make this period a little less trying. Ultimately, there’s a purpose to all the turmoil: your little one is gaining melatonin production and making some big developmental leaps. Keep focusing on a consistent bedtime routine and know that this too will pass.

What to know about growth charts and percentiles

At each of your child’s well-checks, the pediatrician will plot their weight, length and head circumference on a growth chart, the same one they’ve used since they were born. Growth charts show how your baby has grown over time and how a baby’s weight or length may be compared to that of other babies who are the same age.

As an example, let’s say your baby’s weight is in the 75th percentile. That means that 25% of babies of the same age and sex weigh more, and 75% of babies weigh less. All babies grow at their own pace, and can be healthy at a wide range of percentiles. Your child’s pediatrician will be looking at the overall growth pattern, or curve, of their growth chart to make sure your child is showing steady, sustained growth over time.

Average baby weight in months 7, 8 and 9

During the final stretch of the first year, growth starts to slow down a bit, at least in comparison to the first 6 months. That said, your baby’s development is ramping up. Your lovebug will be working on reaching major developmental milestones in months 7 to 9, like potentially crawling, pulling themselves up to stand, and maybe saying their first word. It’s an exciting time! 

Read on for the average weight according to the WHO and CDC.

Average weight at 7 months

Related: 7-month-old baby health & growth guide

Average weight at 8 months

  • An 8-month-old baby boy in the 50th percentile weighs 19 pounds (8.6 kilograms) 
  • An 8-month-old baby girl in the 50th percentile weighs 17 pounds, 7 ounces (7.9 kilograms)

Related: 8-month-old baby health & growth guide

Average weight at 9 months

Related: 9-month-old baby health & growth guide

Feeding and nutrition

Now’s the time where you’ll want to introduce a wide variety of foods, including vegetables, fruit, grains and proteins, and you can start to get creative with combinations and mash-ups. Just watch out for added salt and sugar—and stay away from anything too hard or small and round (potential choking hazards). 

As your baby’s feeding schedule starts to center more around family meal times, you can begin to stretch out breast milk and formula feedings more too, though milk should still be your baby’s primary source of nutrition and calories until age 1. 

Sleep patterns

In the name of being mentally prepared, there’s another sleep progression coming. The 8-month sleep regression/progression is timed with a big developmental leap, and might signify some interrupted sleep for you and your little one. But keep consistent with your naptime and nighttime routines and you’ll both sail through relatively unscathed. Thankfully, many parents find that around 9 months, sleep becomes more stable—and life with an infant feels a little easier overall. Phew.

When should I worry about my baby’s growth?

Your baby’s growth should generally be following a consistent curve. Try not to stress too much:  While your 1-month-old baby’s weight is one metric of how well they’re developing, it’s not the only one. Head circumference and length also play a role, as well as developmental milestones.

According Boston Children’s Hospital, signs of slow growth in babies may include the following:

  • If your baby doesn’t regain their birth weight in the first 14 days after birth

  • If your newborn up to 3 months isn’t gaining around an ounce a day

  • If your baby has been growing steadily and suddenly stops growing

If you’re concerned, reach out to your child’s pediatrician. They’ll examine how frequently your little one is feeding, how much they’re taking in at each feed, and the number of wet and dirty diapers to try to get the full picture.

Average baby weight in months 10, 11 and 12

Your baby is becoming more of their own person every day. From showing more interest in foods to learning to grasp objects and understanding simple instructions, it’s hard to believe they were a teeny newborn mere months ago. By their first birthday, generally speaking, your baby should have tripled their birth weight. Though their weight gain rate has slowed down as compared to their first six months of life, they should still gain a few ounces each month between months 10 through 12.

Average weight at 10 months

Related: 10-month-old baby health & growth guide

Average weight at 11 months

Related: 11-month-old baby health & growth guide

Average weight at 12 months

Related: 12-month-old baby health & growth guide

Feeding and nutrition

Your little one wants to take in the world around them at every moment, which means they can get distracted while breastfeeding or taking a bottle. When you can, try to feed them in a darkened, quiet environment, away from potential distractions. Or if that’s not working, go the opposite route: feed them while babywearing, while you walk, or while listening to music or an audiobook. Although solids are gaining more importance in their world, the nutrition they get from breast milk or formula is still essential to their growth and development at this stage.

Sleep patterns

Your little one may be ready to drop a nap around the 9- or 10-month mark, which means they’ll likely be going from three naps a day to two. Now’s a good time to start being strategic around wake windows, ensuring that the longest wake stretch is in the afternoon, before bedtime. This helps promote a regular sleep pattern and sets your baby up to sleep for a longer stretch at night. Getting your little one on a regular sleep schedule now can pay off in the long run—for both of you. 

A note from Motherly on your baby’s first year of growth

Take stock, mama. We hope you’ll look back on this first year of remarkable growth and change and see just how far you’ve both come. From first smiles to first steps, you’ve both truly grown—and blossomed—together, every inch and ounce along the way. And just remember, if you have any questions or concerns, reach out to your child’s pediatrician, who can help you determine next best steps.

A version of this story was originally published on July 15, 2023. It has been updated.

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