How to use
- Choose the reference — CDC (used in the United States, ages 2–20) or WHO (ages 0–19) — and the child's sex.
- Enter the age in years and months, then height and weight in cm and kg or inches and pounds.
- Read the BMI, percentile and weight category, then check the healthy range and the chart.
Options explained
- BMI-for-age percentile (CDC)
- Compares your child's BMI with children of the same age and sex in the CDC reference. The 60th percentile means a BMI higher than 60 out of 100 children.
- CDC categories
- Underweight below the 5th percentile; healthy weight from the 5th to below the 85th; overweight from the 85th to below the 95th; obesity at or above the 95th; severe obesity at or above 120% of the 95th percentile.
- WHO categories
- Based on Z-scores (standard deviations). Under 5 years — above +1 at risk of overweight, above +2 overweight, above +3 obesity. From 5 to 19 — above +1 overweight, above +2 obesity. Below −2 is thinness and below −3 severe thinness at any age.
CDC BMI cut-offs by age
BMI values (kg/m²) where each category starts, from the CDC 2000 BMI-for-age charts.
| Age | Boys 5th | Boys 85th | Boys 95th | Girls 5th | Girls 85th | Girls 95th |
|---|---|---|---|---|---|---|
| 4 | 14.0 | 16.9 | 17.8 | 13.7 | 16.8 | 18.0 |
| 6 | 13.7 | 17.0 | 18.4 | 13.4 | 17.1 | 18.8 |
| 8 | 13.8 | 18.0 | 20.1 | 13.5 | 18.3 | 20.7 |
| 10 | 14.2 | 19.4 | 22.2 | 14.0 | 20.0 | 23.0 |
| 12 | 15.0 | 21.0 | 24.2 | 14.8 | 21.7 | 25.3 |
| 14 | 16.0 | 22.7 | 26.0 | 15.8 | 23.3 | 27.3 |
| 16 | 17.1 | 24.2 | 27.6 | 16.8 | 24.7 | 28.9 |
What the result means
BMI is a screening measure. It cannot tell muscle from fat, and children grow in spurts, so one reading in the overweight or underweight range is a reason to talk to your pediatrician, not a diagnosis. Tracking BMI over time on the chart is more useful than a single number.
Frequently asked questions
Why not use the adult BMI chart for a child?
Children's body fat changes as they grow — BMI normally falls after infancy and rises again from about age 6 — so a BMI of 18 is healthy for a 12-year-old but high for a 5-year-old. Percentiles compare a child with others of the same age and sex.
Why does the result show a percent of the 95th percentile?
Above the 95th percentile the original CDC percentiles are not precise. Since 2022 the CDC describes high BMIs as a percentage of the 95th percentile; 120% or more is severe obesity.
CDC or WHO?
In the United States, the CDC recommends the WHO charts under age 2 and the CDC charts from 2 to 20. Most other countries use the WHO references. The two can give slightly different categories near the cut-offs.
Is my child's data saved?
No. Everything is calculated in your browser and nothing is uploaded.
Privacy
This tool runs entirely in your browser. Your files and text are processed on your device and are never uploaded to our servers.