Average Height and Weight for Children by Age — Complete Guide

Average height and weight charts give parents and clinicians a reference point — not a target. A child who consistently tracks at the 25th percentile for both height and weight is growing normally for their individual pattern, even though they are smaller than most peers.

What matters most is not where a child falls on the chart at any single visit, but whether they are following a consistent growth curve over time. Sudden changes in percentile — either up or down — are more meaningful than the absolute number.

Growth charts are built from large population studies. The WHO standard, used for children 0–2, describes how children grow under optimal conditions worldwide. The CDC reference, used for ages 2–20, describes how U.S. children actually grew in national surveys.

At birth, most full-term babies fall within a fairly predictable range. The average newborn weighs about 3.3 kg (7.3 lbs) and measures approximately 50 cm (19.7 inches) in length.

Babies typically lose 5–10% of birth weight in the first few days, then regain it by 10–14 days of age. By 5 months, most babies have doubled their birth weight; by 12 months, most have tripled it.

The first year of life is the fastest growth period outside the womb. Babies gain roughly 150–200 g per week in the first few months, slowing to about 85–140 g per week by 6 months.

Head circumference is also measured at every visit during the first year. The average head circumference at birth is about 34–35 cm, growing to approximately 46–47 cm by 12 months.

Growth slows considerably after the first birthday. Toddlers typically gain about 2–3 kg (4–6 lbs) and grow 7–13 cm (3–5 inches) per year between ages 1 and 3.

This is also when BMI-for-age becomes a useful screening tool alongside weight-for-age. The CDC recommends switching from WHO to CDC growth charts at age 2.

Between ages 3 and 5, children grow at a steady, predictable pace — roughly 5–7 cm (2–3 inches) taller and 2 kg (4–5 lbs) heavier each year. Boys and girls are very similar in size during this period.

By age 5, most children are about double their birth length and approximately 5–6 times their birth weight.

The school-age years are a period of steady, gradual growth. Children typically gain about 3–3.5 kg (6–7 lbs) and grow 5–6 cm (2–2.5 inches) per year. Boys and girls remain similar in size until around age 10–11, when girls often begin their pubertal growth spurt first.

Notice that by age 12, girls have caught up with — and slightly surpassed — boys in both height and weight, reflecting their earlier pubertal timing.

Adolescence brings the most dramatic growth changes since infancy. Boys typically experience their peak height velocity around age 13–14, while girls peak around age 11–12. After the growth spurt, height gains slow and eventually stop — usually by age 16–17 for girls and 18–19 for boys.

By age 18–20, most individuals have reached their adult height. The male–female height gap widens significantly during adolescence, with adult men averaging about 17–18 cm taller than adult women in the U.S.

"Average" on a growth chart means the 50th percentile — exactly half of children are above it and half are below. Most healthy children do not grow at exactly the 50th percentile, and that is completely normal.

• A child who consistently tracks at any percentile between P3 and P97 is generally growing normally.
• Crossing two or more major percentile channels over a short period is more concerning than being at a low percentile.
• Genetics play the largest role, so parent height and build matter for context.
• Illness, nutritional changes, and stress can temporarily affect growth.