Paediatric BMI: percentile for age
Calculates BMI from 2 to 20 years and classifies it by the CDC 2000 percentile.
When to use
Child or adolescent from 2 to 20 years whose weight is classified by age and sex instead of a fixed adult cutoff.
Pearls and pitfalls
- The reference is different before 2 years: the CDC BMI for age starts at 24 months.
- BMI alone does not separate lean mass from fat, so interpretation is clinical and longitudinal.
- The cutoffs are the CDC ones: below the 5th percentile underweight, 85th overweight and 95th obesity.
- The percentile comes from the z score through the normal curve; the value is not read from a band table.
- At the extremes the percentile is shown as 0.1 and 99.9, because no chart supports an exact endpoint.
Fill in the fields to see the result.
Formula
BMI = weight ÷ height². z score = ((BMI ÷ M)^L − 1) ÷ (L × S), with L, M and S interpolated at the age in months; percentile from the normal curve.
Evidence
The 2000 CDC growth reference, the one used in United States growth charts, with published LMS parameters by sex and month of age.
References
- Kuczmarski RJ, Ogden CL, Guo SS, et al. 2000 CDC Growth Charts for the United States: methods and development. Vital Health Stat 11. 2002;(246):1-190. doi:10.1542/peds.2004-1952
Frequently asked questions
What is Paediatric BMI: percentile for age?
Calculates BMI from 2 to 20 years and classifies it by the CDC 2000 percentile. Child or adolescent from 2 to 20 years whose weight is classified by age and sex instead of a fixed adult cutoff.
How is the result calculated?
BMI = weight ÷ height². z score = ((BMI ÷ M)^L − 1) ÷ (L × S), with L, M and S interpolated at the age in months; percentile from the normal curve.
How should the result be interpreted?
The 2000 CDC growth reference, the one used in United States growth charts, with published LMS parameters by sex and month of age.
What are the sources?
Kuczmarski RJ, Ogden CL, Guo SS, et al. 2000 CDC Growth Charts for the United States: methods and development. Vital Health Stat 11. 2002;(246):1-190.