Weight-for-length for boys at 109 cm

At a length of 109 cm, the median weight for boys on the WHO Child Growth Standards is 17.9 kg (39 lb 8 oz): half of boys of this length weigh less and half more. The middle half of boys, from the 25th to the 75th percentile, falls between 16.9 and 19.0 kg, a spread of 2.10 kg. The outer lines of the chart, the 2nd and 98th percentiles, sit at 15.1 and 21.4 kg.

At 107 cm the median weight is 17.3 kg, so 2 cm of extra length goes with about 0.66 kg more weight at the median. At 110 cm it is 18.3 kg. 109 cm is close to the median height of boys at 5 years (108.9 cm). Weight-for-length compares a child's weight with other children of the same length, whatever their age, which is why it can read differently from weight-for-age for a long or a short baby.

For girls at a length of 109 cm the median is 18.0 kg, 0.03 kg more than for boys, which is why the charts are drawn separately by sex.

CDC 2000 weight-for-length tables stop at 103.5 cm, so at 109 cm only the WHO standard applies.

Reading the table: a boy at a length of 109 cm who weighs 18.6 kg is at about the 66th percentile, meaning that out of 100 boys of that length, about 66 weigh less.