Child BMI Calculator
Calculate BMI percentile for children and teens aged 2–19 using CDC growth chart standards.
About Child BMI Percentile
Child BMI is age- and sex-specific because body fatness changes substantially with age. The CDC uses BMI-for-age percentile charts to classify weight status in children aged 2–19. Percentile indicates how a child's BMI compares to peers of the same age and sex.
Accuracy This calculator uses interpolated CDC reference data to estimate BMI percentile. Percentile estimates are approximate (±3–5 percentile points) and are intended for screening only. Official CDC growth chart software or a pediatrician's assessment should be used for clinical decisions.
CDC BMI-for-Age Categories
| Percentile | Category |
|---|---|
| Below 5th | Underweight (<5th %ile) |
| 5th – 84th | Healthy Weight (5th–84th %ile) |
| 85th – 94th | Overweight (85th–94th %ile) |
| 95th and above | Obese (≥95th %ile) |
What to do with your result
- Bring the percentile result to your child's next well-child visit and ask your pediatrician to plot it on the official CDC growth chart alongside previous measurements to assess trends.
- If your child is at or above the 85th percentile, focus on family-wide healthy eating habits — increase vegetables, fruits, and whole grains while reducing sugary drinks and ultra-processed snacks — without singling out the child.
- Aim for your child to get at least 60 minutes of moderate-to-vigorous physical activity daily through play, sports, or active transport like walking or cycling to school.
- Avoid using weight as a topic of shame or criticism; instead frame healthy habits as things the whole family does together to feel strong and energetic.
Frequently Asked Questions
Why is child BMI calculated differently from adult BMI?
Children's body fat percentage changes naturally as they grow, and differs between boys and girls. For this reason, BMI in children is expressed as a percentile compared to peers of the same age and sex rather than as a fixed cutoff. This age- and sex-specific approach gives a far more accurate picture of a child's weight status than adult BMI categories.
What BMI percentile is healthy for a child?
According to CDC guidelines, a BMI percentile between the 5th and 84th is considered healthy weight. Below the 5th percentile is classified as underweight, between the 85th and 94th percentile is overweight, and at or above the 95th percentile is classified as obese.
Should I be concerned if my child's BMI is high but they look healthy?
BMI percentile is a screening tool, not a diagnostic test. Some muscular or large-framed children may have a high BMI percentile without excess body fat. Conversely, a child can have a normal BMI but still have health concerns. A pediatrician can assess the full picture using growth trends, physical examination, and other health markers.
How often should I check my child's BMI?
The American Academy of Pediatrics recommends that BMI be calculated and plotted at every well-child visit — typically annually for school-age children and adolescents. Tracking BMI over time (the percentile trajectory) is more informative than a single measurement.
What should I do if my child is classified as overweight or obese?
Consult your child's pediatrician before making significant changes. In most cases, the goal for growing children is to maintain current weight while they grow taller, rather than active weight loss. Focus on family-based strategies: reducing sugary drinks and processed foods, increasing physical activity to 60 minutes daily, and improving sleep — without using shame or food restriction.
This calculator is for educational purposes only. Consult a qualified healthcare professional for medical advice.