An 11-month-old typically weighs between 17 and 22 pounds, depending on sex and individual growth patterns. The average (50th percentile) weight for an 11-month-old girl is about 19.2 pounds (8.7 kg), while boys tend to weigh slightly more at this age. More important than hitting any single number is whether your baby has been growing steadily along their own curve over the past several months.
Average Weight by Percentile
Pediatricians in the United States use World Health Organization growth charts for all children under 2. These charts are based on data from healthy breastfed infants across multiple countries and represent how children grow under optimal conditions. For 11-month-old girls, the WHO standards break down like this:
- 5th percentile: 15.9 pounds (7.2 kg)
- 50th percentile: 19.2 pounds (8.7 kg)
- 95th percentile: 23.6 pounds (10.7 kg)
Boys at 11 months typically weigh about a pound more than girls at each percentile. A baby at the 5th percentile is not necessarily underweight, and a baby at the 95th percentile is not necessarily overweight. Percentiles describe where your child falls relative to other children the same age. What matters most is consistency: a baby who has tracked along the 25th percentile since birth is growing exactly as expected, even though they weigh less than average.
What “Normal” Growth Looks Like at This Age
Between 10 and 12 months, babies gain an average of about 13 ounces per month. That’s noticeably slower than the rapid gains of the first few months. By their first birthday, most babies have tripled their birth weight. So if your baby was born at 7 pounds, you’d expect them to be somewhere around 21 pounds by 12 months.
Growth at this age can be uneven. A baby who is learning to crawl or pull up to stand may burn more calories and gain weight more slowly for a few weeks, then catch up. Teething, minor illnesses, and changes in appetite can also cause temporary slowdowns. A single weigh-in that looks low or high is rarely a concern on its own. Your pediatrician looks at the pattern over multiple visits.
Why Breastfed and Formula-Fed Babies Differ
Breastfed babies typically gain weight more slowly than formula-fed babies during the first year. This difference becomes noticeable after about 3 months of age and continues even after solid foods are introduced. Both groups grow in length at similar rates, so the difference is specifically in weight and body composition rather than overall size.
This is one reason the CDC recommends the WHO growth charts for children under 2. The WHO charts are based on breastfed infants and reflect healthy growth rather than the slightly faster weight gain that formula feeding produces. If your breastfed baby looks lighter compared to formula-fed peers, that’s expected and not a sign they need supplementation.
Factors That Influence Your Baby’s Weight
Genetics play the biggest role. Tall, lean parents tend to have babies who track along lower weight percentiles, while stockier families tend to produce heavier babies. Birth weight also matters: research shows that a higher birth weight raises the risk of tracking higher on growth charts through childhood. Babies born to mothers with gestational diabetes, for example, often start larger and may stay above average.
Sleep is another factor that gets overlooked. Babies who get enough sleep are more likely to maintain a healthy weight. At 11 months, most babies need about 12 to 14 hours of total sleep per day, including naps. Screen time, even at this young age, is associated with a greater risk of excess weight gain.
Calorie Needs at 11 Months
An 11-month-old needs roughly 750 to 900 calories per day. About 400 to 500 of those calories should still come from breast milk or formula, which works out to approximately 24 ounces per day. The rest comes from solid foods. At this age, most babies are eating three small meals plus one or two snacks, with a mix of soft table foods and purees.
If your baby seems to be eating well but gaining weight slowly, the calorie density of their food may be the issue. Fruits and vegetables are nutritious but low in calories. Adding healthy fats like avocado, nut butters (thinly spread), or olive oil to meals can help. On the other hand, if your baby is gaining faster than expected, it’s worth checking whether they’re getting more than 24 to 32 ounces of formula daily, since overfeeding from a bottle is one of the more common causes of rapid weight gain at this age.
Premature Babies and Adjusted Age
If your baby was born prematurely, their weight should be compared to growth charts using their corrected age, not their actual birth date. A baby born two months early who is now 11 months old would be plotted at 9 months on the growth chart. Pediatricians use corrected age for growth tracking until age 2. Some premature infants also need specialized growth charts designed specifically for preterm babies, particularly if they were born very early or at a very low birth weight.
Catch-up growth is common in premature babies, but it happens on its own timeline. Some preemies reach the weight range of their full-term peers by 12 months, while others take longer. Consistent upward movement on the growth curve is what your pediatrician watches for.
Signs That Weight May Be a Concern
A single measurement outside the “normal” range rarely signals a problem. Pediatricians look for red flags like crossing two or more percentile lines in either direction over a short period, falling below the 2nd percentile, or weight that flatlines for several months. Other signs that your baby’s weight deserves a closer look include persistent lethargy, fewer than four wet diapers a day, or loss of developmental milestones.
Rapid upward crossing of percentile lines can also warrant attention, though it’s less commonly flagged at this age. In most cases, a baby who looks healthy, is meeting developmental milestones, and is eating a variety of foods is growing exactly the way they should, regardless of where they fall on the chart.