The Body Mass Index (BMI) Calculator accurately evaluates biometric weight status and personal body mass index while factoring in chronological age and biological sex. Select the "Metric Units" tab for international standard metric values or the "Other Units" tab to seamlessly convert measurements between imperial and metric systems. In addition to primary BMI analysis, this engine calculates ponderal index, target healthy weight intervals, and BMI prime metrics explained comprehensively below.
BMI introduction
Body mass index represents an established physiological screening metric assessing an individual's relative tissue mass and corpulence by comparing total body weight against standing height. Clinical practitioners, healthcare networks, and epidemiological researchers worldwide rely on BMI as a fast, noninvasive benchmark for identifying potential weight-related wellness hazards. Calculated values place individuals into specific diagnostic tiers—underweight, healthy weight, overweight, or clinical obesity classes—signaling general body composition and metabolic health. These clinical thresholds can vary across global geographic populations, ethnic backgrounds, and demographic groups, occasionally utilizing granular subcategories like moderate thinness or severe obesity. Sustained deviations from healthy weight ranges can influence cardiovascular and metabolic well-being; thus, while BMI does not directly differentiate skeletal muscle from adiposity, it serves as an indispensable initial guidepost. Review the comprehensive clinical reference table below to see standard diagnostic classifications applied throughout this tool.
BMI table for adults
The World Health Organization (WHO) establishes these universally recognized adult weight classification thresholds based on standardized BMI intervals. These clinical benchmarks serve as primary diagnostic criteria for adult men and women aged 20 years and older.
| Classification | BMI range - kg/m² |
|---|---|
| Severe Thinness | < 16 |
| Moderate Thinness | 16 - 17 |
| Mild Thinness | 17 - 18.5 |
| Normal | 18.5 - 25 |
| Overweight | 25 - 30 |
| Obese Class I | 30 - 35 |
| Obese Class II | 35 - 40 |
| Obese Class III | > 40 |
BMI chart for adults
This clinical visualization maps adult body mass index categories across comprehensive height and weight distributions based on official WHO data. The distinct color-coded bands identify key weight categories, while fine contour lines represent continuous integer BMI gradations for diverse body proportions.
BMI table for children and teens, age 2-20
The Centers for Disease Control and Prevention (CDC) recommends standardized growth-percentile distributions for pediatric BMI evaluation in children and adolescents aged 2 through 20.
| Category | Percentile Range |
|---|---|
| Underweight | < 5% |
| Healthy weight | 5% - 85% |
| At risk of overweight | 85% - 95% |
| Overweight | > 95% |
BMI chart for children and teens, age 2-20
Official CDC pediatric growth charts delineate BMI-for-age percentile trajectories, enabling parents and healthcare providers to monitor healthy juvenile developmental milestones.