1. What is BMI Percentile for Children?

The BMI percentile indicates how a child's BMI compares to other children of the same age and gender. It's calculated using the LMS method which accounts for the skewed distribution of BMI values in children.

2. How Does the Calculator Work?

The calculator uses the LMS method equation:

Where:

• \( BMI \) — Body Mass Index (kg/m²)
• \( M \) — Median BMI for age and gender
• \( L \) — Box-Cox power (skewness parameter)
• \( S \) — Coefficient of variation
• \( \Phi \) — Standard normal cumulative distribution

Explanation: The LMS method transforms BMI values to follow a normal distribution, allowing percentile calculation.

3. Importance of BMI Percentile

Details: BMI percentile is the standard measure for assessing weight status in children. Categories are:

• Underweight: <5th percentile
• Healthy weight: 5th to <85th percentile
• Overweight: 85th to <95th percentile
• Obese: ≥95th percentile

4. Using the Calculator

Tips: Enter BMI in kg/m², age in years (2-20), and select gender. For accurate results, use exact age and measured height/weight.

5. Frequently Asked Questions (FAQ)

Q1: Why use percentiles instead of BMI categories for children?
A: Children's body composition changes with growth, so percentiles account for normal age and gender differences.

Q2: Where do the L, M, S values come from?
A: These are derived from large growth chart studies like CDC or WHO growth standards.

Q3: How often should BMI percentile be checked?
A: Annually for healthy children, more frequently if tracking growth concerns.

Q4: What if my child is above the 99th percentile?
A: Extreme percentiles may indicate need for further evaluation by a healthcare provider.

Q5: Does this work for all ages?
A: Typically used for ages 2-20. For younger children, weight-for-length percentiles are more appropriate.