1. Enter values for gender, height and weight.
2. The result is interpreted within four categories: Underweight (<5th percentile), Healthy weight (5th-85th percentile), Overweight (85th-95th percentile) and Obese (>95th percentile).
3. To evaluate height in relation to age click the "Evaluate height button"
4. Please note, that BMI is only a very rough predictor for overweight in individuals.
For adults, the body mass index limits for overweight and obesity are straight forward (overweight = BMI > 25 and obesity = BMI > 30). For children this is much more complicated as the limits vary a lot depending on age. This calculator uses the US guidelines that are based on fixed percentiles from a large reference population.
A BMI of 20 indicates obesity in a 6 year old girl, whereas it would represent healthy weight for a 13 year old girl. However, as growth of children varies, the final evaluation should always be based on a several factors including physical growth, muscularity and subcutaneous fat deposits.
The calculator also includes the possibility to evaluate height in relation to age. If the child/youth scores in the high percentile range on height (above average) this could indicate that physical development is ahead of chronological age. As higher BMI is expected with increasing age (above age 6), this information can assist in a qualified evaluation of BMI.
Mei Z, Grummer-Strawn LM, Pietrobelli A, Goulding A, Goran MI, Dietz WH. Validity of body mass index compared with other body-composition screening indexes for the assessment of body fatness in children and adolescents. American Journal of Clinical Nutrition 2002;7597–985.
Pietrobelli A, Faith MS, Allison DB, Gallagher D, Chiumello G, Heymsfield, SB. Body mass index as a measure of adiposity among children and adolescents: A validation study. Journal of Pediatrics. 1998; 132:204–210.