Child BMI is calculated differently from adult BMI — it is plotted on age and sex-specific growth charts and expressed as a percentile compared to peers of the same age and sex.
Unlike adult BMI which uses fixed cut-offs, child BMI-for-age is plotted on growth charts and expressed as a percentile compared to other children of the same age and sex.
NHS / CDC Percentile Categories:
Below 5th percentile: Underweight
5th–84th percentile: Healthy weight
85th–94th percentile: Overweight
95th percentile or above: Obese
BMI is a screening tool only — not a diagnosis. Children grow at different rates. Please speak with your child's GP or health visitor before drawing any conclusions from a calculator result.