ADULT BMI CALCULATOR
Calculate Body Mass Index for adults age 20 and older
BMI RESULT
Enter age, height, and weight to calculate adult BMI.
ABOUT THIS RESULT
BMI is a screening measure based on height and weight. It does not diagnose a medical condition and does not directly measure body fat.
BMI cannot distinguish body fat from muscle, bone, or other components of body weight. Medical history, physical examination findings, blood pressure, laboratory results, and other information may be needed for a broader health assessment.
Children and teenagers ages 2 through 19 should not be evaluated with the adult ranges shown here. Their results require BMI-for-age percentiles based on age and sex.
Adult BMI Calculator and Categories
Body Mass Index, commonly abbreviated as BMI, is a calculation that compares an adult’s weight with the square of their height. The result is expressed in kilograms per square meter and placed within a standard adult BMI category.
Age Requirement
This calculator is intended only for adults age 20 and older. Standard adult BMI categories are applied regardless of adult age or sex.
Children and teenagers ages 2 through 19 must be evaluated differently. Their BMI is compared with people of the same age and sex using BMI-for-age percentiles. Entering a child’s measurements into an adult calculator can produce an incorrect category.
BMI Formula
For metric measurements, BMI is calculated with the following formula:
BMI = weight in kilograms ÷ height in meters²
For pounds and inches, the calculation is:
BMI = weight in pounds ÷ height in inches² × 703
Adult BMI Categories
The following ranges apply to adults age 20 and older:
| Adult BMI category | BMI range |
|---|---|
| Underweight | Below 18.5 |
| Healthy weight | 18.5 to below 25.0 |
| Overweight | 25.0 to below 30.0 |
| Obesity, Class 1 | 30.0 to below 35.0 |
| Obesity, Class 2 | 35.0 to below 40.0 |
| Obesity, Class 3 | 40.0 or higher |
Interpreting a BMI Result
BMI is a screening measure rather than a diagnosis. It provides a general comparison of weight relative to height but does not directly measure body fat or determine an individual’s overall health.
BMI cannot distinguish fat mass from muscle, bone, or other components of body weight. People with the same BMI can have different body compositions and different health circumstances.
A broader health assessment may include medical history, physical examination findings, blood pressure, laboratory results, health behaviors, and other relevant information. The calculator does not provide personalized dietary, exercise, weight-loss, weight-gain, or medical recommendations.
BMI for Children and Teenagers
For people ages 2 through 19, BMI must be interpreted using age- and sex-specific percentiles rather than the fixed adult ranges listed above. The CDC Child and Teen BMI Calculator provides BMI, BMI percentile, and the corresponding child or teen category.
CDC Child and Teen BMI Calculator
Sources and References
- Adult BMI Categories — Centers for Disease Control and Prevention, March 19, 2024. Last checked July 12, 2026.
- About Body Mass Index — Centers for Disease Control and Prevention, December 16, 2025. Last checked July 12, 2026.
- Child and Teen BMI Calculator — Centers for Disease Control and Prevention, June 26, 2024. Last checked July 12, 2026.
- BMI Frequently Asked Questions — Centers for Disease Control and Prevention, June 28, 2024. Last checked July 12, 2026.
