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Child BMI Percentile Calculator

Find your child's BMI percentile per CDC growth charts (ages 2–20). Accounts for age + sex — not just absolute BMI.

Health

Child BMI Percentile Calculator

Generated on April 25, 2026

Child & teen BMI is interpreted by PERCENTILE, not absolute number. A 14-year-old's "normal" BMI is very different from an adult's — this calculator looks up the right comparison group.
Healthy weight
16.3 BMI
≈ 45th percentile for 10.0-year-old boys.

Reference percentiles for this age

5th
14.2
Underweight
50th
16.6
Median
85th
19.6
Overweight starts
95th
22.1
Obesity starts

CDC growth chart (BMI vs age)

152025302y5y10y15y20yYouBMI (kg/m²)
5th pct
50th pct
85th pct
95th pct
Your child

Step-by-step calculation

Formula

Child BMI = weight (kg) ÷ height (m)². Percentile from CDC 2000 growth chart by age + sex.

  1. 1Age: 10.0 years (male).
  2. 2Weight: 32.0 kg, height: 140.0 cm.
  3. 3BMI = 32.0 / (1.40)² = 16.33.
  4. 4For age 10.0 male: 5th=14.2, 50th=16.6, 85th=19.6, 95th=22.1.
  5. 5Estimated percentile: 44.9th → Healthy weight.
  6. 6CDC categories: <5th = Underweight; 5-85 = Healthy; 85-95 = Overweight; ≥95 = Obesity.
Estimates use simplified linear interpolation between published CDC reference points. For clinical accuracy your pediatrician uses the full LMS tables (per-month resolution). For Pakistan-specific local growth norms, your doctor may apply slightly different cutoffs (Pakistani children average ~5-10% below US reference values at the same age).

?What is the Child BMI Percentile Calculator?

The Child BMI Percentile Calculator interprets a child's or teenager's BMI by age and sex, using CDC 2000 growth-chart reference data — the standard worldwide for pediatric growth assessment. Unlike adults (where a BMI of 25 is always 'overweight'), a child's BMI must be interpreted in context: a 6-year-old with BMI 18 is overweight, but a 16-year-old with the same BMI is normal. Categories per CDC: Underweight (<5th percentile), Healthy (5-85th), Overweight (85-95th), Obesity (≥95th). Linear interpolation is used between published age anchors for an instant estimate; clinical pediatric assessment uses the full LMS tables for per-month resolution.

The Formula

Child BMI = weight (kg) / height (m)². Result interpreted as a percentile against a same-age, same-sex reference population.

Practical Examples

1

10-year-old boy, 32 kg, 140 cm: BMI 16.3 ≈ 50th percentile (healthy median).

2

8-year-old girl, 35 kg, 130 cm: BMI 20.7 ≈ 95th+ percentile (obesity).

3

16-year-old girl, 50 kg, 165 cm: BMI 18.4 ≈ 25th percentile (healthy, on the lean side).

4

5-year-old: Healthy BMI range is 14-17. Adult-style 'normal' BMI numbers don't apply — kids are leaner.

5

Teen growth spurts can shift percentile rapidly. A single reading isn't enough — track over multiple visits.

Frequently Asked Questions

Because children's body composition changes dramatically with age. A 4-year-old's healthy BMI median is ~15.5; a 17-year-old's is ~21. Adult BMI categories (25 = overweight, 30 = obese) don't apply to growing bodies. Percentiles compare a child to peers of the same age and sex.

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