Pediatric BMI Calculator

No. BMI itself is only Weight divided by Height squared -- Age and Sex never enter that calculation. What Age and Sex do change is how that same BMI number is interpreted: the Percentile and weight Category compare the child's raw BMI against real CDC reference values for their specific age and sex group, so two children with an identical BMI can land in very different percentile categories if they're different ages.

Because the CDC reference median BMI for a given age group shifts as children grow -- it actually dips slightly through the preschool years before climbing again around age 5-6 (the real "adiposity rebound" pattern in the CDC BMI-for-age data this calculator reads from). A BMI that sits right at the 50th percentile at one age can read as a different percentile a few years later purely because the reference median moved, even with no change in the child's own BMI.

It converts the 5th-to-85th BMI percentile band from the real CDC reference curve -- the range this calculator classifies as Normal Weight -- back into kilograms at the child's current height. It's a target weight window for this specific height and age/sex group, not a universal healthy weight for children of that age.

Obese is the standard CDC cutoff (BMI-for-age at or above the 95th percentile). Severe Obesity is a stricter, separately-flagged threshold: BMI at or above 120% of the age/sex 95th-percentile BMI value itself (not 120% of the percentile score) -- the current CDC/AAP convention for identifying children whose obesity is severe enough to warrant closer clinical attention than the plain 95th-percentile threshold alone communicates.

BMI-for-age is only a standard, validated screening tool from age 2 through 20, matching the CDC's own published BMI-for-age reference range. Infants and toddlers under 2 are tracked using weight-for-length charts instead, since BMI behaves differently and less reliably as a screening measure in that age range.