BMI Calculator for Kids - Calculate Child BMI Percentile
Free online BMI calculator for kids (5-19 years). Calculate BMI percentile using WHO growth standards and get personalized health insights.
Medical Disclaimer
The health and fitness tools provided on this website are for informational and educational purposes only. The information contained herein is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. The results provided by these tools are estimates based on general formulas and may not apply to your specific situation. If you think you may have a medical emergency, immediately call your doctor or dial emergency services.
BMI Calculator for Kids & Teens
Welcome to our comprehensive BMI Calculator for Kids and Teens, designed specifically for children aged 5-19 years. This advanced tool uses WHO (World Health Organization) child growth standards to calculate BMI-for-age percentiles, the gold standard for pediatric weight assessment.
Unlike adult BMI, child BMI must be interpreted relative to age and gender. Our calculator uses the LMS method (Lambda-Mu-Sigma) to calculate z-scores and convert them to percentiles, following WHO growth reference data for 5-19 year olds.
Key features:
- Accurate BMI-for-age percentile calculation using WHO standards
- Interactive growth chart visualization with percentile curves
- Peer comparison analysis (how your child compares to others)
- Future health risk assessment based on current growth pattern
- Long-term growth projection up to age 19
- Expert recommendations tailored to your child's age and gender
- Support for both metric (cm, kg) and imperial (ft, in, lbs) units
Whether you're monitoring your child's growth, concerned about weight, or just curious about their development, this tool provides valuable, evidence-based insights. Always consult a pediatrician for medical advice.
- WHO-standard BMI-for-age percentile calculation for 5-19 year olds
- Interactive growth chart visualization with percentile curves
- Peer comparison and future health risk assessment
- Long-term growth projection up to age 19
- Expert recommendations tailored to age and gender
- Complete support for both metric and imperial units
FAQ About Child & Teen BMI
How do you calculate BMI for kids?
Child BMI is calculated the same way as adult BMI (weight kg / height m²), but the result is compared to growth charts of children of the same age and gender. Instead of fixed categories, we use percentiles: <5th = underweight, 5th-85th = healthy, 85th-95th = overweight, ≥95th = obese.
What is a normal BMI for a child?
Normal BMI for children varies by age and gender. A healthy weight is defined as a BMI-for-age percentile between the 5th and 85th percentiles, according to WHO growth standards for children and teens aged 5-19 years.
Does BMI work for children?
Yes, but BMI-for-age percentiles are used instead of adult categories. BMI-for-age is the recommended screening tool by WHO and CDC for assessing weight status in children and teens aged 5-19, though it should be interpreted by healthcare professionals.
How to read a BMI chart for children?
Child BMI charts show age on the x-axis and BMI or percentile on the y-axis. Find your child's age, then trace up to their BMI. The percentile curves (3rd, 15th, 50th, 85th, 97th) show how they compare to peers. Our calculator visualizes this automatically.
When should I worry about my child's BMI?
Consult a pediatrician if your child is below the 5th percentile (underweight) or at/above the 85th percentile (overweight/obese). Also watch for rapid changes in BMI percentile, regardless of category, as this may indicate health concerns.
What is pediatric BMI percentile calculation example?
Let's calculate for a 10-year-old boy, 140 cm tall, weighing 35 kg. First, BMI = 35 / (1.40)² = 17.9. Using WHO growth standards for 10yo boys, mean BMI (M) is ~17.3, standard deviation (S) ~1.7. Z-score = (ln(17.9) - ln(17.3)) / 1.7 ≈ 0.20. Percentile ≈ 58th, which is healthy!