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BMI Standards & Authority Guide

BMI Result

0.00
WHO Standard Category
Healthy Weight Range57kg - 76kg
Mathematical Model: Quetelet Index

Explore the science, history, and mathematical framework of Body Mass Index.

Body Mass Index (BMI) & The Quetelet Index

The Body Mass Index (BMI), originally called the Quetelet Index, was developed by Adolphe Quetelet, a Belgian statistician, in 1832. It is a mathematical ratio designed to estimate body fat based on height and weight.

The Mathematical Formula

BMI = weight (kg) ÷ [height (m)]²

WHO Classification Standards

BMI RangeCategory
Below 18.5Underweight
18.5 – 24.9Healthy Weight
25.0 – 29.9Overweight
30.0 and AboveObese

Technical Limitations & Accuracy

It is critical to note that BMI is a screening tool, not a diagnostic one. It does not measure body fat percentage directly and may be inaccurate for athletes (high muscle mass) or the elderly (muscle loss).

The Mathematical Shift: New BMI Formula

Some mathematicians argue that the standard BMI formula is skewed for very tall or short people. The "New BMI" formula, proposed by Oxford University, uses a power of 2.5:

New BMI = 1.3 × weight (kg) ÷ height2.5 (m)

Clinical Application

While widely used, clinical assessments should ideally combine BMI with waist circumference and body fat percentage for a holistic health view.