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Your child on the CDC growth chart
The curves show BMI percentiles for boys from age 2 to 20. Add measurements over time to see how your child's BMI tracks along them.
- Underweight (below 5th)
- Healthy (5th to below 85th)
- Overweight (85th to below 95th)
- Obesity (95th and above)
Saved measurements
Saved only in this browser| Measured | Age | BMI | Percentile | Remove |
|---|
No measurements saved yet. Use Add to growth chart after each checkup to build a history.
How the percentile was calculated
Every percentile calculator does this behind the scenes. Here is the same math, using your child's numbers and the CDC reference data.
Why kids get a percentile instead of a BMI category
Children's body fat changes a lot as they grow, and differently for boys and girls. BMI normally falls from age 2 to about age 5 or 6, then rises through the teen years.1 So the same BMI can mean very different things at different ages.
BMI-for-age categories
These CDC categories apply to children and teens aged 2 through 19.2
| Percentile | Category |
|---|---|
| Below the 5th | Underweight |
| 5th to below the 85th | Healthy weight |
| 85th to below the 95th | Overweight |
| 95th and above | Obesity |
Severe obesity: percent of the 95th percentile
Above the 95th percentile, percentiles bunch together and stop being useful. Instead, the CDC compares a child's BMI with the BMI at the 95th percentile for their age and sex.3 For example, a BMI 20% above the 95th-percentile value is 120% of the 95th percentile.
| % of the 95th percentile | Class |
|---|---|
| 100% to below 120% | Obesity class 1 |
| 120% to below 140% | Severe obesity, class 2 |
| 140% and above | Severe obesity, class 3 |
For parents: measuring and talking about BMI
Measure accurately
Shoes off, back against a flat wall, eyes looking straight ahead. Weigh in light clothes on a hard floor. A 1-inch error in height can move a young child's percentile noticeably. How to measure at home.
Look at the trend
One measurement is a snapshot. A child who stays near the same percentile curve over time is usually growing as expected. Big jumps across curves are worth asking about.
Keep the focus on habits
Talk with children about energy, sleep, play and food they enjoy, not about weight or numbers. Your pediatrician can help put a result in context.
Talk to your child's doctor if the result is below the 5th or at or above the 85th percentile, or the percentile has changed quickly. Bring it up at the next checkup; there's no need to wait for a special visit. When to see a doctor.
Frequently asked questions
Is BMI calculated differently for kids?
No. The BMI formula is the same. What changes is how the number is read: it is compared with other children of the same age and sex, and reported as a percentile.
What age does the kids BMI calculator cover?
Ages 2 through 19, using the CDC growth charts.1 From age 20, use the adult BMI calculator. Under age 2, doctors use weight-for-length charts instead of BMI.
Why do boys and girls have different charts?
Boys and girls gain body fat at different rates and times, especially around puberty. Separate charts make the comparison fair.
How do I calculate a BMI percentile by hand?
You need the CDC's L, M and S values for the child's age and sex. Use them to calculate a z-score, then convert the z-score to a percentile. The steps above show the full math with your numbers. See the method in detail.
Why did my child's BMI go up when they look the same?
BMI naturally rises as children get older, especially after age 6. That is why the percentile, not the BMI number, is what matters for kids.
Sources
This page is for education and is not medical advice. A pediatrician or other healthcare professional can tell you what a BMI percentile means for your child.
