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BMIKID is a 4-digit-numeric variable with two implied decimals.

0: Not in Universe
99.95: 99.95+
99.99: Unknown


BMIKID is the variable identifying Body Mass Index (BMI), a measure of body weight relative to height, was calculated using the formula: BMI = kilograms /[meters, squared]. Kilograms and meters were derived from pounds and inches using the following factors: 1 kilogram=2.20462 pounds; 1 meter=39.37008 inches. BMI was calculated for all sample children aged 12-17 years with a reported current height and weight, including those for whom specific height and weight values were changed to "96" (not available) on the public use file.

BMIKID is derived from the two variables HIEGHTKID and WEIGHTKID. These two variables were subject to data quality checks to ensure accuracy during data collection, as well as data editing of extreme values. To protect the confidentiality of sample children who might be identifiable by their unusual physical characteristics, the highest 1.5 percent of records and the lowest 1.5 percent of records, the sex-specific height-for-age and weight-for-age values of were changed to "96" ("Not available"). For example, a 12 year old girl who weighed 60 lbs. or less (lowest 1.5 percent of records) or 188 lbs. or more (highest 1.5 percent of records) was coded as not available. In cases where extreme values were reported for either current height or current weight, the data for both variables were changed to "Not available" on the public use data file.

BMI variable values are released as 5-digit numbers with two decimal places implied. For example, a value of 2587 for the BMI variable indicates a 25.87 BMI.


BMIKID is completely comparable from 2008 forward.


  • 2008-2018: Sample children age 12-17.


  • 2008-2018