Child BMI and Nutrition Needs Calculator

ANA›Life Services Authority›National Calculator Authority›Child BMI and Nutrition Needs Calculator

.calc-container { max-width: 640px; margin: 2rem 0; padding: 1.5rem; background: #fff; border: 1px solid #ddd; border-radius: 8px; box-shadow: 0 1px 3px rgba(0,0,0,0.06); font-family: system-ui, -apple-system, sans-serif; } .calc-container h3 { font-family: Georgia, serif; font-size: 1.15rem; color: #1a1a1a; margin-bottom: 1rem; padding-bottom: 0.5rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-row { display: flex; align-items: center; gap: 0.75rem; margin-bottom: 0.75rem; flex-wrap: wrap; } .calc-row label { min-width: 160px; font-size: 0.9rem; color: #333; font-weight: 500; } .calc-row input[type="number"], .calc-row select { flex: 1; min-width: 120px; max-width: 200px; padding: 0.5rem 0.6rem; border: 1px solid #ccc; border-radius: 4px; font-size: 0.9rem; font-family: system-ui, sans-serif; color: #1a1a1a; background: #fafaf8; } .calc-row input:focus, .calc-row select:focus { outline: none; border-color: var(--ac, #3d5a80); box-shadow: 0 0 0 2px rgba(26,74,138,0.12); } .calc-row .unit { font-size: 0.82rem; color: #888; min-width: 30px; } .calc-btn { display: inline-block; margin-top: 0.5rem; padding: 0.55rem 1.5rem; background: var(--ac, #3d5a80); color: #fff; border: none; border-radius: 4px; font-size: 0.9rem; font-weight: 600; cursor: pointer; font-family: system-ui, sans-serif; } .calc-btn:hover { opacity: 0.9; } .calc-result { margin-top: 1.25rem; padding: 1rem 1.25rem; background: #f0f6fc; border-left: 3px solid var(--ac, #3d5a80); border-radius: 0 6px 6px 0; display: none; } .calc-result.visible { display: block; } .calc-result-label { font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.06em; color: #666; margin-bottom: 0.25rem; } .calc-result-value { font-size: 1.6rem; font-weight: 700; color: var(--ac, #3d5a80); } .calc-result-detail { font-size: 0.85rem; color: #555; margin-top: 0.5rem; line-height: 1.5; } .calc-note { margin-top: 1rem; font-size: 0.8rem; color: #888; font-style: italic; } .calc-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 0.75rem; margin-top: 0.75rem; } .calc-grid-item { padding: 0.6rem 0.8rem; background: #f8f9fa; border-radius: 4px; border: 1px solid #eee; } .calc-grid-item .label { font-size: 0.75rem; color: #888; text-transform: uppercase; letter-spacing: 0.04em; } .calc-grid-item .value { font-size: 1.1rem; font-weight: 600; color: #1a1a1a; } @media (max-width: 720px) { .calc-row { flex-direction: column; align-items: flex-start; gap: 0.3rem; } .calc-row label { min-width: auto; } .calc-row input[type="number"], .calc-row select { max-width: 100%; width: 100%; } .calc-grid { grid-template-columns: 1fr; } } .calc-chart { margin: 1rem 0; text-align: center; } .calc-chart svg { max-width: 100%; height: auto; } .calc-chart-legend { display: flex; flex-wrap: wrap; justify-content: center; gap: 0.6rem 1.2rem; margin-top: 0.6rem; font-size: 0.8rem; color: #555; } .calc-chart-legend span { display: inline-flex; align-items: center; gap: 0.3rem; } .calc-chart-legend i { display: inline-block; width: 10px; height: 10px; border-radius: 2px; font-style: normal; } .calc-related { max-width: 640px; margin: 2rem 0 1rem; padding: 1.25rem 1.5rem; background: #f8f9fa; border: 1px solid #e8e8e8; border-radius: 8px; } .calc-related h3 { font-family: Georgia, serif; font-size: 1rem; color: #1a1a1a; margin: 0 0 0.75rem; padding-bottom: 0.4rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-related-list { list-style: none; padding: 0; margin: 0 0 0.75rem; display: grid; grid-template-columns: 1fr 1fr; gap: 0.4rem 1.5rem; } .calc-related-list li a { font-size: 0.88rem; color: var(--ac, #3d5a80); text-decoration: none; } .calc-related-list li a:hover { text-decoration: underline; } .calc-browse-all { margin: 0.5rem 0 0; font-size: 0.9rem; font-weight: 600; } .calc-browse-all a { color: var(--ac, #3d5a80); text-decoration: none; } .calc-browse-all a:hover { text-decoration: underline; } @media (max-width: 720px) { .calc-related-list { grid-template-columns: 1fr; } }

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.

Age (years, 2–18)

Biological Sex

-- Select -- Male Female

Weight Unit

Kilograms (kg) Pounds (lb)

Weight (kg)

Weight (lb)

Height Unit

Centimetres (cm) Feet & Inches

Height (cm)

Height (ft & in)

Activity Level

Sedentary (little/no exercise) Low active (light activity 1–3 days/week) Active (moderate activity 3–5 days/week) Very active (hard exercise 6–7 days/week)

Calculate

function chiToggleWeightUnit() { var u = document.getElementById('chi-weight-unit').value; document.getElementById('chi-weight-kg-row').style.display = u === 'kg' ? '' : 'none'; document.getElementById('chi-weight-lb-row').style.display = u === 'lb' ? '' : 'none'; } function chiToggleHeightUnit() { var u = document.getElementById('chi-height-unit').value; document.getElementById('chi-height-cm-row').style.display = u === 'cm' ? '' : 'none'; document.getElementById('chi-height-in-row').style.display = u === 'in' ? '' : 'none'; }

function chiCalc() { var errors = [];

var age = parseFloat(document.getElementById('chi-age').value); if (isNaN(age) || age 18) errors.push("Age must be between 2 and 18 years.");

var sex = document.getElementById('chi-sex').value; if (!sex) errors.push("Please select a biological sex.");

var weightUnit = document.getElementById('chi-weight-unit').value; var weightKg; if (weightUnit === 'kg') { weightKg = parseFloat(document.getElementById('chi-weight-kg').value); if (isNaN(weightKg) || weightKg 200) errors.push("Weight must be between 5 and 200 kg."); } else { var lb = parseFloat(document.getElementById('chi-weight-lb').value); if (isNaN(lb) || lb 440) errors.push("Weight must be between 11 and 440 lb."); weightKg = lb * 0.453592; }

var heightUnit = document.getElementById('chi-height-unit').value; var heightCm; if (heightUnit === 'cm') { heightCm = parseFloat(document.getElementById('chi-height-cm').value); if (isNaN(heightCm) || heightCm 220) errors.push("Height must be between 50 and 220 cm."); } else { var ft = parseFloat(document.getElementById('chi-height-ft').value) || 0; var inch = parseFloat(document.getElementById('chi-height-in2').value) || 0; var totalIn = ft * 12 + inch; if (totalIn 87) errors.push("Height must be between 1 ft 8 in and 7 ft 3 in."); heightCm = totalIn * 2.54; }

var activity = document.getElementById('chi-activity').value;

var resultDiv = document.getElementById('chi-result'); if (errors.length > 0) { resultDiv.style.display = 'block'; resultDiv.innerHTML = 'Please fix the following:' + errors.map(function(e){ return ''; }).join('') + ''; return; }

// ── BMI ────────────────────────────────────────────────────────────────── var heightM = heightCm / 100; var bmi = weightKg / (heightM * heightM);

// ── BMI-for-age percentile category (CDC LMS approximation) ────────────── // Uses simplified age-based BMI thresholds derived from CDC growth charts // (Kuczmarski et al., 2000). Exact percentile requires LMS lookup tables; // here we use the published cut-points for clinical categories. var bmiCat = chiGetBMICategory(bmi, age, sex);

// ── Estimated Energy Requirement (EER) – IOM / DRI 2005 ────────────────── // Boys 3–8: EER = 88.5 - 61.9×age + PA×(26.7×wt + 903×ht) + 20 // Boys 9–18: EER = 88.5 - 61.9×age + PA×(26.7×wt + 903×ht) + 25 // Girls 3–8: EER = 135.3 - 30.8×age + PA×(10.0×wt + 934×ht) + 20 // Girls 9–18: EER = 135.3 - 30.8×age + PA×(10.0×wt + 934×ht) + 25 // ht in metres, wt in kg; PA = physical activity coefficient var PA; if (sex === 'male') { var paMap = {sedentary:1.00, low:1.13, active:1.26, very:1.42}; PA = paMap[activity]; } else { var paMapF = {sedentary:1.00, low:1.16, active:1.31, very:1.56}; PA = paMapF[activity]; }

var eer; var energyDeposit = age '; html += 'MetricValue'; html += 'BMI' + bmi.toFixed(1) + ' kg/m²'; html += 'BMI Category' + bmiCat.label + ''; html += 'Estimated Daily Energy (EER)' + Math.round(eer) + ' kcal/day'; html += 'Carbohydrates (45–65 % kcal)' + Math.round(carbMinG) + '–' + Math.round(carbMaxG) + ' g/day'; html += 'Protein (AMDR 10–30 % kcal)' + Math.round(protMinG) + '–' + Math.round(protMaxG) + ' g/day'; html += 'Protein (DRI RDA ' + protRDA_gkg + ' g/kg)' + protRDA.toFixed(1) + ' g/day'; html += 'Fat (25–35 % kcal)' + Math.round(fatMinG) + '–' + Math.round(fatMaxG) + ' g/day'; html += 'Dietary Fibre (AI)' + Math.round(fibre) + ' g/day'; html += 'Total Water (AI)' + water + ' L/day'; html += 'Calcium (AI/RDA)' + calcium + ' mg/day'; html += 'Iron (RDA)' + iron + ' mg/day'; html += '';

html += 'These are population-level estimates. Consult a paediatrician or registered dietitian for personalised advice.

';

resultDiv.style.display = 'block'; resultDiv.innerHTML = html; }

// ── Helper: BMI category using CDC age/sex-specific cut-points ──────────── // Simplified from CDC 2000 growth chart percentile tables: // Underweight

#### 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:

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

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