AT A GLANCE
- 01Height and weight
- 02Age and sex
- 03Appropriate reference
Children need age and sex references
The growth tool compares BMI by age in months and sex using WHO 2007 references. Fixed adult cutoffs should not be applied to a child's result.
Adults use a separate tool
The website’s adult BMI tool is for people aged 20 and above and returns an index with a general reference category. BMI does not directly measure body composition or fitness.
Context still matters
A single result cannot diagnose health. For concerning changes or questions about growth, speak with a professional who can consider the full context.
References
- WHO — Height-for-age (5–19 years)
- WHO — BMI-for-age (5–19 years)
- WHO — Weight-for-age (5–10 years)
- WHO — Computation of centiles and z-scores
Reviewed on 3 October 2026. These sources do not endorse or certify Siroby.