Calculate BMI-for-age for boys aged 5–19 years. Enter age, height and weight to estimate BMI and compare it with reference values for boys of the same age.
Supported age range: 61–228 months. Enter completed years and any additional months for the most appropriate comparison.
How boys’ BMI is calculated
The BMI formula is the same as for adults—weight in kilograms divided by height in metres squared—but a child’s number must be interpreted by age and sex. The calculator compares the result with BMI-for-age reference values for boys. Measure height without shoes and use a current, accurate weight where possible.
Understanding the percentile range
A percentile compares the result with the reference population of boys of the same age. A result around the 75th percentile, for example, means the BMI is equal to or higher than that of approximately 75% of boys of the same age in the reference data.
- Underweight: below the 5th percentile
- Healthy weight: from the 5th percentile to below the 85th percentile
- Overweight: from the 85th percentile to below the 95th percentile
- Obesity: at or above the 95th percentile
Reference data and limitations
The calculator’s age- and sex-specific values are based on the WHO 2007 growth reference for ages 5–19. The descriptive percentile bands follow the categories explained by the CDC for child and teen BMI.
BMI is a screening measure, not a diagnosis. Growth pattern, development, medical history and other factors matter. Discuss concerns or unexpected results with a qualified healthcare professional. For girls, use the girls BMI calculator; for people aged 20 and older, use the adult BMI calculator.
Reference information reviewed 29 August 2026. Do not use this calculator as a substitute for professional medical advice.