A ten-month-old boy typically weighs around 20 pounds (9.2 kg), while a ten-month-old girl typically weighs around 18.7 pounds (8.5 kg), based on the 50th percentile of WHO growth charts. But “typical” covers a wide range. Babies anywhere from the 5th to the 95th percentile are generally growing normally, which means a healthy ten-month-old could weigh anywhere from about 15 to 25 pounds depending on sex, genetics, and birth size.
Average Weight by Sex
The 50th percentile represents the midpoint, where half of babies weigh more and half weigh less. For boys at ten months, that’s roughly 20.2 pounds. For girls, it’s about 18.7 pounds. These numbers come from the WHO growth standards, which pediatricians in the U.S. use for children under two.
Your baby’s percentile matters less than their consistency on that percentile over time. A baby who has tracked along the 20th percentile since birth is growing perfectly well. A baby who was at the 75th percentile and has dropped to the 20th percentile over a few months is a different situation, even though both babies might weigh exactly the same at ten months.
Why Weight Gain Slows Down Around This Age
Most babies double their birth weight by about five months and triple it by their first birthday. But the rate of gain slows considerably in the second half of the first year. Between ten and twelve months, the average baby gains about 13 ounces per month, a noticeable drop from the rapid gains of the early months.
Some babies actually lose a small amount of weight around this time, and there are a few common reasons. Ten-month-olds are often crawling, pulling to stand, and cruising along furniture, burning far more calories than they did as younger, less mobile babies. They may also be more interested in exploring than eating, treating mealtime as playtime instead. A recent illness can cause a temporary dip too. These short-term fluctuations are normal as long as the overall trend stays on track.
What Percentiles Actually Tell You
Growth percentiles describe where your baby falls relative to other babies of the same age and sex. A baby at the 30th percentile weighs more than 30% of babies and less than 70%. That’s not a grade. Being at the 15th percentile doesn’t mean your baby is underweight any more than being at the 85th means they’re overweight.
What pediatricians watch for is a pattern called “crossing percentiles.” The American Academy of Pediatrics recommends evaluation when a baby’s weight drops across two major percentile lines (for example, falling from around the 75th percentile to below the 25th). A single weigh-in that seems low isn’t usually cause for concern. The trajectory over several visits tells the real story, which is why regular well-child checkups matter so much during the first year.
Factors That Influence Your Baby’s Weight
Genetics play the biggest role. If both parents are on the smaller side, a baby tracking at the 15th percentile is doing exactly what their genes dictate. Birth weight and length set an initial trajectory, though some babies “catch up” or “catch down” in the first six months before settling into their own curve.
Feeding method can influence weight patterns too. Breastfed babies tend to gain weight faster in the first few months and then slow down compared to formula-fed babies, who often gain more steadily through the second half of the first year. By ten months, breast milk or formula still serves as the primary source of nutrition, with solid foods gradually making up a larger share of the diet. Babies who have taken enthusiastically to solids may weigh differently than those who are still warming up to table food.
Premature babies follow a different timeline. Pediatricians often use a “corrected age” for growth tracking, meaning a baby born two months early would be compared against the charts for an eight-month-old, not a ten-month-old. This adjusted comparison typically continues until age two.
Signs of a Growth Problem
Most parents who search for weight ranges are looking for reassurance, and most of the time, their baby is fine. But there are signs that a baby’s growth has genuinely stalled. A baby experiencing growth faltering (the current clinical term for what used to be called “failure to thrive”) may show several overlapping signals: not gaining weight as expected over multiple visits, not growing in length, excessive crying, sleeping more than usual or falling asleep during feedings, and not interacting with people in age-appropriate ways like mimicking facial expressions or responding to their name.
No single sign on that list is alarming on its own. A ten-month-old who sleeps a lot but is gaining weight and hitting milestones is just a good sleeper. The concern arises when poor weight gain appears alongside other developmental or behavioral changes. If your baby’s growth curve has flattened or dropped and you’re noticing any of these patterns together, that’s worth bringing up at your next visit rather than waiting.
Feeding at Ten Months
At this age, breast milk or formula remains the nutritional foundation. Solid foods are increasingly important but are still supplementary. Most ten-month-olds eat three small meals of soft table foods or purees alongside their usual milk feeds.
Babies’ stomachs are small, so portions look tiny by adult standards. A tablespoon or two of food at a time is normal. Offering a variety of textures and flavors matters more than quantity at this stage. Some days your baby will eat enthusiastically, and other days they’ll reject everything. This inconsistency is developmentally normal and rarely affects growth when milk intake stays steady. If your baby seems to be refusing both solids and milk consistently over several days, or if they’re losing interest in feeding altogether, that’s a more meaningful signal than one skipped meal.