BMI Calculator: Calculate Your Body Mass Index

What is Body Mass Index (BMI)?

The Body Mass Index (BMI) is an anthropometric ratio derived by dividing an individual’s weight in kilograms by the square of their height in meters ($kg/m^2$). Developed in the 19th century by Belgian mathematician Adolphe Quetelet, it is utilized worldwide by the World Health Organization (WHO), national health agencies, and epidemiologists as a rapid, population-level screening tool.

Official WHO Adult BMI Classifications

Crucial Scientific Limitations of BMI

While BMI provides a fast statistical baseline, it carries well-documented limitations that prevent it from functioning as a standalone diagnostic of personal health:

• Cannot Distinguish Muscle from Fat: Bodybuilders, resistance athletes, and power athletes frequently register as "overweight" or "obese" despite having very low body fat and exceptional cardiovascular fitness.
• Ignores Fat Distribution: Visceral adipose tissue (fat stored around internal organs in the abdomen) carries significantly higher metabolic risk than subcutaneous fat stored around the hips and thighs, a distinction BMI cannot capture.
• Age and Ethnic Variations: Older adults naturally lose skeletal muscle mass (sarcopenia), which can mask elevated body fat under a "normal" BMI. Certain populations (such as South Asian adults) experience increased metabolic risk at lower BMI thresholds (≥23 kg/m²).