BMI Calculator
BMI Calculator
Calculate your Body Mass Index (BMI) using your age, gender, height and weight.
Your BMI Result
— kg/m²
- Healthy adult BMI range: 18.5–24.9
- Healthy weight estimate:
- BMI Prime:
- Ponderal Index: kg/m³
BMI is a screening measure, not a diagnosis. Discuss health concerns with a qualified healthcare professional.
What Is BMI?
Body Mass Index (BMI) is a screening measure calculated from a person's weight and height. It can help indicate whether an adult's weight falls within a commonly used range, but it does not directly measure body fat or distinguish fat from muscle.
BMI Formula
For metric measurements:
BMI = weight in kilograms ÷ height in metres²
For US measurements:
BMI = 703 × weight in pounds ÷ height in inches²
BMI Categories for Adults
| Category | BMI (kg/m²) |
|---|---|
| Underweight | Below 18.5 |
| Healthy 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 |
What Is BMI Prime?
BMI Prime compares a person's BMI with the upper limit of the standard healthy adult BMI range (25). It is calculated as BMI ÷ 25.
What Is the Ponderal Index?
The Ponderal Index is another height-and-weight measure. In metric units, it is calculated as weight in kilograms divided by height in metres cubed.
Limitations of BMI
BMI does not account fully for muscle mass, body-fat distribution, age-related changes or individual health circumstances. It should be considered alongside other information, such as waist measurements, medical history and advice from a healthcare professional.
Adult BMI categories are not used in the same way for children and teenagers aged 2–19. Their BMI is interpreted using age- and sex-specific growth percentiles. This calculator does not interpret those percentiles.