Weight for boys at 9 years
At 9 years, the median weight for boys on the CDC 2000 growth charts is 28.6 kg (62 lb 15 oz): half of boys this age weigh less and half more. The middle half of boys, from the 25th to the 75th percentile, falls between 25.7 and 32.2 kg, a spread of 6.52 kg. The outer lines of the chart, the 3rd and 97th percentiles, sit at 22.0 and 42.8 kg.
Since 8 years, the median has risen by 2.91 kg over 1 year. By 10 years it reaches 31.9 kg.
For girls at 9 years the median is 29.0 kg, 0.44 kg more than for boys, which is why the charts are drawn separately by sex.
From 2 years CDC recommends its own 2000 growth charts, which draw the 3rd to the 97th percentile; under 2, the WHO charts draw the 2nd to the 98th.
Reading the table: a boy at 9 years who weighs 30.8 kg is at about the 67th percentile, meaning that out of 100 boys this age, about 67 weigh less.
Percentiles at 9 years
Download CSV (all ages)| Percentile | z-score | Metric | Imperial |
|---|---|---|---|
| 3rd | −1.88 | 21.99 kg | 48 lb 8 oz |
| 5th | −1.64 | 22.62 kg | 49 lb 14 oz |
| 10th | −1.28 | 23.67 kg | 52 lb 3 oz |
| 25th | −0.67 | 25.72 kg | 56 lb 11 oz |
| 50th (median) | 0.00 | 28.55 kg | 62 lb 15 oz |
| 75th | +0.67 | 32.24 kg | 71 lb 1 oz |
| 90th | +1.28 | 36.69 kg | 80 lb 14 oz |
| 95th | +1.64 | 40.14 kg | 88 lb 8 oz |
| 97th | +1.88 | 42.82 kg | 94 lb 6 oz |
CDC 2000 charts draw the 3rd to the 97th percentile. Values computed with the LMS method from the published tables (retrieved 2026-10-05).