BMI Calculator
Calculate your Body Mass Index (BMI). Choose US, EU, or International units for weight and height.
About this calculator
What is BMI?
Body Mass Index (BMI) is a simple ratio of weight to height used to classify underweight, healthy weight, overweight, and obesity in adults. It is widely used in public health screening because it is easy to calculate and correlates with body fat at the population level.
BMI does not directly measure body fat. Athletes with high muscle mass may have a high BMI without excess fat. Always interpret BMI alongside other health indicators.
BMI = weight (kg) ÷ height (m)²
How to use this calculator
Select US, EU, or International units, enter your weight and height, then click Calculate. Your result includes a BMI value and weight category based on WHO adult standards.
Reference tables & standards
WHO adult BMI classification
Source: World Health Organization (WHO)| Category | BMI range |
|---|---|
| Underweight | Below 18.5 |
| Normal weight | 18.5 – 24.9 |
| Overweight | 25.0 – 29.9 |
| Obesity Class I | 30.0 – 34.9 |
| Obesity Class II | 35.0 – 39.9 |
| Obesity Class III | 40.0 and above |
WHO uses the same cut-offs for adults in most populations. Asian populations may use lower overweight thresholds in some national guidelines.
CDC adult BMI categories (United States)
Source: U.S. Centers for Disease Control and Prevention (CDC)| Category | BMI range |
|---|---|
| Underweight | Below 18.5 |
| Healthy weight | 18.5 – 24.9 |
| Overweight | 25.0 – 29.9 |
| Obesity | 30.0 and above |
These calculators provide estimates for educational purposes only. They are not a substitute for professional medical advice, diagnosis, or treatment.