BMI Calculator
Calculate Body Mass Index, BMI Prime & Ponderal Index.
BMI Introduction
BMI is a measurement of a person's leanness or corpulence based on their height and weight, and is intended to quantify tissue mass. It is widely used as a general indicator of whether a person has a healthy body weight for their height.
BMI Table for Adults
This is the World Health Organization's (WHO) recommended body weight based on BMI values for adults (age 20+).
| 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 |
Risks Associated with Being Overweight
Being overweight increases the risk of a number of serious diseases and health conditions, including:
- High blood pressure
- High LDL cholesterol ("bad cholesterol")
- Type II diabetes
- Coronary heart disease
- Stroke
- Sleep apnea and breathing problems
BMI Prime
BMI prime is the ratio of a person's measured BMI to the upper limit of BMI that is considered "normal" (usually 25 kg/m²). It is a dimensionless value useful for comparison.
Formula: BMI Prime = BMI / 25
Ponderal Index
The Ponderal Index (PI) is similar to BMI but uses the cube of the height rather than the square. It is often considered more reliable for very tall or very short individuals.
Formula (Metric): PI = Mass (kg) / Height³ (m)