Estimate your baby's weight and height percentile for their age.
Estimate only, based on general growth patterns. Not a diagnosis.
One of the most common things parents ask at every pediatrician visit is, "Is my baby growing normally?" Growth charts and percentiles were created to answer exactly that question, by comparing a baby's weight and height to typical ranges seen in large populations of children the same age.
Our Baby Growth Percentile Calculator lets you enter your baby's age, sex, weight and height to get an instant, approximate percentile estimate, along with the typical median values for comparison. It is free, works on any device and needs no sign-up.
A percentile shows how a baby's measurement compares to other babies of the same age and sex. If a baby is at the 60th percentile for weight, it means that, in a typical reference population, about 60% of babies of the same age and sex weigh less, and about 40% weigh more. Percentiles run from close to 0 to close to 100, with the 50th percentile representing the statistical median, that is, right in the middle.
Babies come in a wide range of healthy sizes, influenced heavily by genetics, so there is no single "correct" weight or height for a given age. Percentiles solve this by comparing each baby only to others of the same age and sex, which is far more useful than a single fixed number. This is why a pediatrician is usually far less concerned with where a baby sits on the chart today, and far more focused on whether that position stays roughly consistent over time.
| Age | Typical Weight (Boys) | Typical Weight (Girls) |
|---|---|---|
| Birth | ~3.3 kg | ~3.2 kg |
| 3 months | ~6.4 kg | ~5.8 kg |
| 6 months | ~7.9 kg | ~7.3 kg |
| 12 months | ~9.6 kg | ~8.9 kg |
| 24 months | ~12.2 kg | ~11.5 kg |
These figures are approximate medians (50th percentile) based on general growth reference patterns and are shown here for context. Individual healthy babies vary widely around these numbers.
| Age | Typical Height (Boys) | Typical Height (Girls) |
|---|---|---|
| Birth | ~49.9 cm | ~49.1 cm |
| 3 months | ~61.4 cm | ~59.8 cm |
| 6 months | ~67.6 cm | ~65.7 cm |
| 12 months | ~75.7 cm | ~74.0 cm |
| 24 months | ~87.1 cm | ~86.4 cm |
As with weight, these are approximate medians shown for context, and individual healthy babies vary meaningfully around these figures.
Real clinical growth charts, such as those published by the WHO and CDC, are built from detailed statistical curves (called LMS curves) fitted to large population studies, broken down by age in exact days or weeks. This calculator uses a simplified approximation based on typical median and spread values at each age, which gives a reasonable estimate for general awareness, but is not as precise as the official charts your pediatrician uses, which account for finer age increments and measurement details.
Pediatricians actually track several different growth curves, not just one. Weight-for-age and height-for-age, which this calculator estimates, show overall growth compared to peers. Weight-for-height (or later, BMI-for-age) compares a baby's weight relative to their own height, which helps identify whether a baby is proportionate, rather than simply large or small overall. A baby who is tall and heavy might have a high weight-for-age percentile but a completely normal weight-for-height, since the two are proportionate. This is one more reason a single percentile number should always be interpreted by a professional alongside the full picture.
| Percentile Range | General Interpretation |
|---|---|
| 3rd - 97th percentile | Generally considered within the typical range |
| Below 3rd percentile | May warrant closer monitoring by a pediatrician |
| Above 97th percentile | May warrant closer monitoring by a pediatrician |
| Sudden percentile jump or drop | Often more significant to a pediatrician than the number itself |
These ranges are general guidance, not strict cutoffs. Many perfectly healthy babies fall outside the 3rd-97th range, and your pediatrician will always consider your baby's full history, family growth patterns, and overall health, not a single measurement.
Research has shown that breastfed and formula-fed babies tend to follow slightly different growth patterns in the first year. Breastfed babies often gain weight a little faster in the first few months and then more slowly in the second half of the first year, compared to formula-fed babies. The WHO growth standards, widely used internationally, are specifically based on breastfed babies as the healthy growth reference, while some regional charts historically used a mixed-feeding population. This is one reason a baby's growth pattern can look slightly different depending on which chart or reference is used, and it is another reason a pediatrician's interpretation matters more than the raw percentile number.
Growth percentiles are a helpful way to understand how a baby's size compares to typical patterns for their age, but they are only one piece of the picture. Use this calculator for a quick, general estimate, and rely on your pediatrician's official growth chart and clinical judgment for an accurate, personalized assessment of your baby's health and development.