Cdc Bmi Percentile Calculator

CDC BMI Percentile Equation:

\[ Z = \begin{cases} \frac{(BMI / M)^L - 1}{L \times S} & \text{if } L \neq 0 \\ \frac{\ln(BMI / M)}{S} & \text{if } L = 0 \end{cases} \] \[ \text{Percentile} = 100 \times \Phi(Z) \]

BMI Percentile:

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the CDC BMI Percentile Calculator?

The CDC BMI Percentile Calculator uses the LMS method to determine a child's BMI percentile based on CDC growth charts. It compares a child's BMI to others of the same age and gender.

2. How Does the Calculator Work?

The calculator uses the LMS equation:

\[ Z = \begin{cases} \frac{(BMI / M)^L - 1}{L \times S} & \text{if } L \neq 0 \\ \frac{\ln(BMI / M)}{S} & \text{if } L = 0 \end{cases} \] \[ \text{Percentile} = 100 \times \Phi(Z) \]

Where:

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

Explanation: The LMS method accounts for the non-normal distribution of BMI in children, with different parameters for each age and gender.

3. Importance of BMI Percentile

Details: BMI percentile is the most common indicator of weight status in children and adolescents. It helps identify underweight, healthy weight, overweight, and obesity.

4. Using the Calculator

Tips: Enter BMI in kg/m², age in years (2-20), and select gender. For accurate results, use exact age (including decimal for months).

5. Frequently Asked Questions (FAQ)

Q1: Why use BMI percentile instead of BMI?
A: BMI percentile accounts for normal growth patterns and variations by age and gender in children.

Q2: What are the BMI percentile categories?
A: Underweight (<5th), Healthy weight (5th-85th), Overweight (85th-95th), Obese (≥95th).

Q3: How often should BMI be measured in children?
A: The AAP recommends annual BMI screening for all children aged 2+ years.

Q4: Are there limitations to BMI percentile?
A: It doesn't distinguish between fat and muscle mass, and may be less accurate for very muscular or very tall children.

Q5: Where can I find the official CDC growth charts?
A: The CDC provides detailed growth charts with LMS values at https://www.cdc.gov/growthcharts/