A two-month-old boy typically weighs around 12.3 pounds (5.6 kg), while a two-month-old girl typically weighs around 11.2 pounds (5.1 kg). These are 50th percentile values on the WHO growth charts, meaning half of healthy babies weigh more and half weigh less. The normal range is wide: a healthy two-month-old can weigh anywhere from about 9 pounds to over 14 pounds depending on sex, birth weight, and feeding method.
Average Weight by Sex
Boys and girls follow slightly different growth curves from birth. At two months, the gap is roughly a pound on average. Here’s what the WHO growth charts show for common percentile ranges at two months of age:
- Boys: 3rd percentile is about 9.7 lbs (4.4 kg), 50th percentile is about 12.3 lbs (5.6 kg), and 97th percentile is about 15.4 lbs (7.0 kg).
- Girls: 3rd percentile is about 8.8 lbs (4.0 kg), 50th percentile is about 11.2 lbs (5.1 kg), and 97th percentile is about 14.1 lbs (6.4 kg).
If your baby falls at the 15th or 85th percentile, that’s completely normal. Percentiles describe where a baby sits relative to other babies of the same age and sex. They are not grades. A baby consistently tracking along the 20th percentile is growing well. What matters most is the pattern over time, not any single number.
How Fast Babies Gain Weight at This Age
In the first few months of life, babies gain about 1 ounce (28 grams) per day. That works out to roughly 5 to 7 ounces per week, or about 1.5 to 2 pounds per month. Most babies double their birth weight by around four to five months.
It’s common for newborns to lose up to 7 to 10 percent of their birth weight in the first few days after delivery. They usually regain it within 10 to 14 days. So when you’re looking at your two-month-old’s weight, the trajectory since about two weeks of age is the most meaningful window. A baby who was born at 7 pounds, dipped to 6.5, and now weighs 11.5 at two months is right on track.
Breastfed vs. Formula-Fed Babies
Breastfed and formula-fed babies often weigh about the same at two months, but their growth patterns start to diverge shortly after. Healthy breastfed infants typically put on weight more slowly than formula-fed infants in their first year. The difference becomes more noticeable after about three months, when formula-fed babies tend to gain weight more quickly. Length growth stays similar regardless of feeding method.
This matters because your pediatrician should be using the WHO growth charts for all children under two, which are based on breastfed infants. Older CDC charts were built from a mix of breastfed and formula-fed babies, and using them can make a breastfed baby’s slower-but-normal gain look like a problem when it isn’t. If you’re breastfeeding and your baby’s weight percentile dips a little between two and six months, that pattern alone isn’t necessarily a concern.
When Weight Is a Concern
Doctors look for specific patterns rather than isolated weights. The biggest red flag is a drop across two or more major percentile lines on the growth chart. A baby who was tracking at the 50th percentile and falls to the 10th over a couple of visits is more concerning than a baby who has always been at the 10th. Falling below the 5th percentile for weight also raises attention, though some small babies are simply genetically small and growing at a healthy rate for their body.
Other signs that a two-month-old may not be getting enough nutrition include fewer than six wet diapers a day, persistent fussiness or lethargy, and not regaining birth weight by two weeks. A baby who is feeding well, alert when awake, producing plenty of wet and dirty diapers, and steadily gaining weight is almost certainly fine, even if the number on the scale seems low compared to a friend’s baby.
Premature Babies and Adjusted Age
If your baby was born before 37 weeks, the numbers above won’t apply directly. Premature babies are assessed using their “adjusted age,” which is their actual age minus the number of weeks they arrived early. A baby born at 32 weeks who is now 2 months old has an adjusted age of about 2 weeks, and their weight should be compared to the growth expectations for a 2-week-old, not an 8-week-old.
Pediatricians use specialized growth charts (called Fenton charts) designed specifically for preterm infants, which track growth from as early as 22 weeks of gestation and transition into the standard WHO charts around term age. Adjusted age is typically used for growth tracking until the child is about two years old, at which point most preemies have caught up to their peers.
What Affects Your Baby’s Weight
Several factors influence where a two-month-old falls on the growth curve. Genetics play the largest role. Tall, large-framed parents tend to have bigger babies, and petite parents tend to have smaller ones. Birth weight matters too: a baby born at 6 pounds will likely weigh less at two months than one born at 9 pounds, even if both are gaining at a healthy rate.
Feeding frequency and effectiveness also influence weight. At two months, most babies eat 8 to 12 times per day if breastfed and 6 to 8 times if formula-fed, consuming roughly 4 to 5 ounces per feeding on formula. Babies going through a growth spurt may temporarily cluster their feedings closer together for a few days, which is normal. Illness, reflux, and tongue ties can all interfere with feeding efficiency and slow weight gain if they aren’t addressed.
Your baby’s weight at the two-month checkup is one data point in a longer story. The overall trend across multiple visits is what tells your pediatrician whether growth is on track.