BMI Calculator for Kids
Calculate child BMI, BMI prime, and healthy weight percentile for boys and girls up to age 10.
Why Child BMI Is Different
BMI for children is not read like adult BMI. A value that looks high for an adult can be healthy for a growing child. Pediatric BMI must be compared with age- and sex-specific reference data. This tool is for ages 2 to 10. For older children, use the BMI Calculator for Teens or Child BMI Percentile Calculator.
Child BMI Formula
$$\text{BMI} = \frac{\text{weight (kg)}}{(\text{height (m)})^2}$$
BMI prime divides child BMI by 25, the adult reference value. It helps compare a child result to adult scale, but percentile and WHO category are the main pediatric outputs.
WHO Weight Categories for Children
- Underweight: below 5th percentile
- Healthy weight: 5th to 85th percentile
- Overweight: 85th to 95th percentile
- Obese: above 95th percentile
Frequently Asked Questions
Can I use adult BMI charts for my child?
No. Children change shape as they grow, so adult cutoffs do not apply. Use age- and sex-specific percentiles instead.
What age range does this calculator support?
This version is designed for children ages 2 through 10. Teens need a separate reference chart.
Is BMI enough to diagnose obesity in kids?
No. BMI is a screening tool. A pediatrician should review growth history, diet, activity, and other health factors.
What is BMI prime?
BMI prime is BMI divided by 25. It shows how far the result sits from the adult reference midpoint.
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