Average Baby Weight & Height by Age (0–5 Years)

The average (50th percentile) newborn boy weighs about 3.3 kg (7 lb 4 oz) and a newborn girl about 3.2 kg (7 lb 1 oz). By 12 months, boys average 9.6 kg (21 lb 3 oz) and girls 8.9 kg (19 lb 11 oz). These are population medians — half of healthy babies will be above, and half below.

A baby at the 10th percentile weighs more than 10% of babies their age and less than 90%. The 50th percentile is the median — the middle of the population. The 90th percentile means heavier than 90% of same-age, same-sex peers. All three are within the 'normal' range. The normal range spans the 3rd to 97th percentile.

Probably not. The average is just the middle of a wide range of healthy babies. What matters is that your baby is growing consistently along their own percentile curve over time, not whether they match the 50th percentile. A baby consistently at the 15th percentile for weight is just as healthy as one at the 85th.

Boys tend to be slightly heavier and longer/taller than girls from birth through the early years, though the differences are small. By adolescence, boys typically overtake girls in height (who grow faster earlier). The differences at 0–5 years are generally only 0.5–2 cm and 0.2–0.5 kg.

The table uses WHO MGRS (Multicentre Growth Reference Study) 2006 data — the gold standard for child growth from 0–5 years. The study enrolled children from Brazil, Ghana, India, Norway, Oman, and the United States raised under optimal conditions (exclusive breastfeeding, non-smoking homes, no chronic illness).

Weight measured on a calibrated infant scale is very accurate (within 10–20 g). Length/height at home can vary by 0.5–2 cm depending on technique. Head circumference at home is typically within 0.5–1 cm if a non-stretch tape is used correctly. Professional measurements at well-child visits are more standardized and reliable for tracking growth.