BMI Calculator
Calculate your Body Mass Index (BMI) to determine if you are at a healthy weight relative to your height.
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BMI Introduction
Body Mass Index (BMI) is a standardized measurement of a person's leanness or corpulence based on their height and weight, designed to quantify active tissue mass. It is internationally utilized by health practitioners and scientific agencies as a foundational indicator of whether an individual possesses an appropriate body weight for their height.
Specifically, the value obtained from calculating BMI serves to place individuals into eight distinct weight ranges: Underweight (comprising severe, moderate, and mild thinness subclasses), Normal Weight, Overweight, and Obese (comprising Class I, II, and III subclasses). These weight tiers directly correspond to metabolic risk factors and cardiovascular health standards formulated by the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC).
BMI Table for Adults
This is the World Health Organization's (WHO) internationally recognized body classification system based on BMI scores for adults aged 20 years or older.
| Classification | BMI Range (kg/m²) | BMI Prime |
|---|---|---|
| Severe Thinness | < 16.0 | < 0.64 |
| Moderate Thinness | 16.0 - 17.0 | 0.64 - 0.68 |
| Mild Thinness | 17.0 - 18.5 | 0.68 - 0.74 |
| Normal Weight | 18.5 - 25.0 | 0.74 - 1.0 |
| Overweight | 25.0 - 30.0 | 1.0 - 1.2 |
| Obese Class I (Moderate) | 30.0 - 35.0 | 1.2 - 1.4 |
| Obese Class II (Severe) | 35.0 - 40.0 | 1.4 - 1.6 |
| Obese Class III (Very Severe) | > 40.0 | > 1.6 |
Risks of Overweight & Obesity
Excess body fat increases the risk of numerous acute and chronic health conditions. According to the CDC, these risks include:
- High blood pressure and hypertension
- Type 2 diabetes mellitus
- Coronary heart disease and myocardial infarction
- Stroke and cardiovascular events
- Gallbladder disease and sleep apnea
- Osteoarthritis and articular cartilage breakdown
- Reduced overall quality of life and clinical mobility impairments
Risks of Being Underweight
Being underweight is associated with physiological deficits and endocrine disruptions, presenting its own set of critical health risks:
- Malnutrition, vitamin deficiencies, and severe anemia
- Osteoporosis and premature bone density loss (osteopenia)
- Decreased immune response and elevated susceptibility to infectious illnesses
- Growth and physical developmental delays in children and teenagers
- Endocrine imbalances and reproductive issues (such as amenorrhea in females)
- Post-surgical complications and slower clinical wound healing rates
Mathematical Formula Foundations
Below are the exact equations utilized globally to compute body composition and relative index scores:
Methodology & Formula: Metric & Imperial BMI Formulas
Standard Reference Calculations
Average Adult Male (Metric)
Overweight Adult Female (Imperial)
Frequently Asked Questions
Get answers to common queries based on clinical literature and fitness research.
For most adults, a healthy BMI is between 18.5 and 24.9. A BMI below 18.5 is considered underweight, 25.0 to 29.9 is overweight, and 30.0 or above is obese.
Yes. BMI does not directly measure body fat or distinguish between fat and lean muscle mass. Therefore, muscular athletes may have a high "overweight" or "obese" BMI despite having low body fat. It also does not account for age, gender, or bone structure.
A high BMI is associated with an increased risk of chronic diseases such as type 2 diabetes, high blood pressure, cardiovascular disease, stroke, sleep apnea, and certain types of cancer.