Child BMI Percentile Calculator
Find a child's BMI and which CDC percentile category it falls into. Enter the child's sex, age, weight, and height, and this calculator returns their BMI plus the underweight, healthy, overweight, and obese ranges for their age and sex.
Rates and fees change frequently. Always confirm the current figures
with the official authority before relying on this result.
Formula
BMI = weight (kg) ÷ height (m)²
Category from CDC age- and sex-specific BMI percentile cutoffs
- A child's BMI uses the same weight ÷ height² formula as adults, but is interpreted with growth charts.
- BMI is compared to CDC percentiles for the same age and sex rather than fixed adult cut-offs.
- Below the 5th percentile is underweight, 5th–85th is healthy, 85th–95th is overweight, and at or above the 95th is obese.
- A healthy BMI rises with age, so the cutoffs differ for each age and sex.
- This is a screening estimate — a paediatrician should interpret a child's growth in context.
10-year-old boy, 32 kg, 138 cm
Inputs
- Sex: male
- Age (years): 10
- Weight (kg): 32
- Height (cm): 138
BMI = 32 ÷ 1.38² ≈ 16.8, which is in the healthy range for a 10-year-old boy (about 14.0–19.4).
Frequently asked questions
What is a BMI percentile?
It shows how a child's BMI compares with other children of the same age and sex, expressed as a percentile band rather than a fixed category.
What percentile is a healthy weight?
The 5th to 85th percentile for the child's age and sex is considered a healthy weight under CDC guidelines.
Why not use adult BMI categories for children?
Children's body composition changes as they grow, so age- and sex-specific percentiles are far more meaningful than fixed adult cut-offs.
My child is above the 85th percentile — what should I do?
Speak with your paediatrician, who can confirm the reading, review growth trends, and advise on diet and activity if needed.
What ages does this cover?
It is designed for ages 2 to 19. For adults 20 and older, use the standard adult BMI calculator.