Average Children Height & Weight by Age (6 to 12)
A practical reference for parents tracking growth through the elementary and middle school years — what CDC charts show as average, when the puberty spurt arrives, and how to read the trend.
What “Average” Means at School Age
For children ages 2 and up, U.S. pediatricians use growth charts from the Centers for Disease Control (CDC), built from nationally representative measurements of American children. The 50th percentile is the median — half of children are above, half below. Anywhere from the 3rd to the 97th percentile is considered statistically normal.
Between ages 6 and 12, growth is generally predictable and slower than infancy. Most kids stay on roughly the same percentile band through these years, until puberty arrives and brings the growth spurt — earlier for most girls, later for most boys.
Average Height by Age (50th Percentile)
| Age | Boys | Girls |
|---|---|---|
| 6 years | 45.6 in (115.9 cm) | 45.3 in (115.1 cm) |
| 7 years | 47.9 in (121.7 cm) | 47.7 in (121.2 cm) |
| 8 years | 50.0 in (127.0 cm) | 50.0 in (127.0 cm) |
| 9 years | 52.0 in (132.1 cm) | 52.2 in (132.6 cm) |
| 10 years | 54.0 in (137.2 cm) | 54.3 in (137.9 cm) |
| 11 years | 55.7 in (141.5 cm) | 56.7 in (144.0 cm) |
| 12 years | 58.7 in (149.1 cm) | 59.4 in (150.9 cm) |
Average Weight by Age (50th Percentile)
| Age | Boys | Girls |
|---|---|---|
| 6 years | 46 lb (20.9 kg) | 45.5 lb (20.6 kg) |
| 7 years | 51 lb (23.1 kg) | 50.5 lb (22.9 kg) |
| 8 years | 57 lb (25.9 kg) | 57 lb (25.9 kg) |
| 9 years | 63 lb (28.6 kg) | 64.5 lb (29.3 kg) |
| 10 years | 70.5 lb (32.0 kg) | 73 lb (33.1 kg) |
| 11 years | 78.5 lb (35.6 kg) | 82 lb (37.2 kg) |
| 12 years | 88 lb (39.9 kg) | 92 lb (41.7 kg) |
Parent takeaway: These are median values from CDC charts. A child consistently above or below average can be just as healthy as one right at the 50th — what matters is whether they track along their own percentile band over multiple visits.
Enter measurements to see your child's height and weight percentiles. Based on CDC growth reference data for U.S. children ages 6 through 12.
Enter the values above and tap Calculate Percentiles.
How Growth Changes from 6 to 12
School-age growth follows a steady pattern until puberty arrives. The transition is usually gradual, but the timing differs notably between boys and girls:
When Growth Concerns a Pediatrician
Pediatricians plot height and weight at every well-child visit precisely so a single off number is not taken out of context. The patterns that warrant a closer look are:
What Affects Growth at School Age
Tips for Healthy Growth at School Age
References
Frequently Asked Questions
The average American 6-year-old boy is about 45.6 inches (115.9 cm) tall; the average girl is about 45.3 inches (115.1 cm). The normal range at this age stretches roughly from 42 to 49 inches (3rd to 97th percentile) for both sexes.
The average American 10-year-old boy weighs about 70.5 pounds (32 kg); the average girl weighs about 73 pounds (33.1 kg). The normal range stretches from roughly 53 to 102 pounds (3rd to 97th percentile), reflecting how much variation is normal at this age — especially as puberty begins for some kids and not others.
For girls, the first signs of puberty (breast development) typically appear between ages 8 and 13, with the peak growth spurt usually around ages 11 to 12. For boys, the first signs (testicular enlargement) typically appear between ages 9 and 14, with the peak growth spurt usually around ages 13 to 14. Late bloomers can start 1 to 2 years later than these averages and still reach a normal adult height.
The average American 12-year-old boy is about 58.7 inches (149.1 cm); the average girl is about 59.4 inches (150.9 cm). Girls are often slightly taller than boys at age 12 because most have entered puberty earlier. The normal range is wide — roughly 54 to 65 inches — because puberty timing varies a lot at this age.
Genuine slow growth has clinical markers, not just being short for age. The signs that warrant a pediatrician conversation are growth velocity under 2 inches per year, crossing two or more percentile bands downward between visits, or short stature paired with other symptoms like fatigue, frequent illness, or delayed puberty. A consistently short child who is healthy, growing steadily on their own curve, and has shorter parents is almost always normal.
