BMI (Body Mass Index)
Embed This Widget
Add the script tag and a data attribute to embed this widget.
Embed via iframe for maximum compatibility.
<iframe src="https://unitfyi.com/iframe/glossary/body-mass-index/" width="420" height="400" frameborder="0" style="border:0;border-radius:10px;max-width:100%" loading="lazy"></iframe>Paste this URL in WordPress, Medium, or any oEmbed-compatible platform.
https://unitfyi.com/glossary/body-mass-index/Add a dynamic SVG badge to your README or docs.
[](https://unitfyi.com/glossary/body-mass-index/)Use the native HTML custom element.
Definition
The Body Mass Index (BMI) is a screening metric calculated by dividing a person's weight in kilograms by the square of their height in meters (kg/m²).
Explanation
Developed by Belgian statistician Adolphe Quetelet around 1832, BMI was intended as a population-level statistical tool, not an individual diagnostic. The WHO defines underweight as BMI below 18.5, normal weight as 18.5–24.9, overweight as 25–29.9, and obese as 30 and above. BMI does not distinguish muscle from fat and has been criticized for systematically misclassifying athletes and underestimating health risks in some ethnic groups.
RELATED ARTICLES
From milligrams to metric tons, this guide covers every major weight and mass unit with exact conversion factors, real-world examples, and a clear explanation of why weight and mass are not the same thing.
Complete Guide to Length Units: From Nanometers to Light-YearsA comprehensive reference covering every major length unit—metric, imperial, nautical, and astronomical—with exact conversion factors and real-world scale examples.
RELATED TERMS
Blood Pressure Units
Blood pressure is measured in millimeters of mercury (mmHg), expressed as two values: systolic pressure (heart contracting) over diastolic pressure (heart at rest), e.g., 120/80 mmHg.
Tire Size Numbers
Tire size is encoded in the format Width/AspectRatio R Diameter (e.g., 205/55 R16), where width is in millimeters, aspect ratio is the sidewall height as a percentage of width, and diameter is the wheel rim size in inches.