Child BMI and Nutrition Needs Calculator
Estimate your child's BMI, BMI-for-age percentile category, and recommended daily calorie, protein, carbohydrate, and fat intake based on age, sex, weight, and height.
Formulas Used
BMI: BMI = weight (kg) ÷ height² (m²)
BMI Category: Age- and sex-specific percentile cut-points from CDC 2000 growth charts: Underweight < 5th percentile; Healthy 5th–84th; Overweight 85th–94th; Obese ≥ 95th percentile.
Estimated Energy Requirement (EER) – IOM/DRI 2005:
- Boys: EER = 88.5 − 61.9 × age(y) + PA × (26.7 × wt(kg) + 903 × ht(m)) + energy deposit (20 kcal ages 3–8; 25 kcal ages 9–18)
- Girls: EER = 135.3 − 30.8 × age(y) + PA × (10.0 × wt(kg) + 934 × ht(m)) + energy deposit
- PA coefficients (boys): Sedentary 1.00 | Low 1.13 | Active 1.26 | Very Active 1.42
- PA coefficients (girls): Sedentary 1.00 | Low 1.16 | Active 1.31 | Very Active 1.56
Macronutrients (AMDR – IOM 2005): Carbohydrate 45–65 % kcal; Protein 10–30 % kcal; Fat 25–35 % kcal (4/4/9 kcal per gram respectively).
Protein RDA: 1.1 g/kg/day (ages 4–13); 0.95 g/kg/day (ages 14–18).
Fibre AI: 14 g per 1,000 kcal consumed.
Assumptions & References
- BMI percentile categories follow CDC Clinical Growth Charts (Kuczmarski et al., 2000; Vital Health Stat 11(246)).
- EER equations from Institute of Medicine (IOM) Dietary Reference Intakes for Energy, 2005.
- Acceptable Macronutrient Distribution Ranges (AMDR) from IOM DRI Macronutrients, 2005.
- Protein RDA from IOM DRI Protein and Amino Acids, 2005.
- Calcium and Iron values from IOM DRI Minerals, 2011 and 2001 respectively.
- Total water Adequate Intakes (AI) from IOM DRI Water, Potassium, Sodium, Chloride, and Sulfate, 2005.
- EER equations were validated for children aged 3–18; a 800 kcal floor is applied for edge cases.
- BMI is a screening tool, not a diagnostic measure. Results do not replace clinical assessment.
- Calculations assume typical healthy children without chronic conditions affecting metabolism.