The Body Mass Index (BMI) is a statistical measurement which compares a person's weight and height.

Though it does not actually measure the percentage of body fat, it is a useful tool to estimate a healthy body weight based on how tall a person is.

Due to its ease of measurement and calculation, it is the most widely used diagnostic tool to identify disordered eating problems.

However it is not considered appropriate to use as a final indication for diagnosing individuals.

A body mass index of below 16.5 or above 30 may indicate disordered eating.

Body mass index is defined as the individual's body weight divided by the square of his height.

The formulas universally used in medicine produce a unit of measure of kg/m2:

Calculating Body Mass Index (BMI)

Kilograms and meters (or centimeters)

Formula: weight (kg) / [height (m)]²

With the metric system, the formula for BMI is weight in kilograms divided by height in meters squared.

Since height is commonly measured in centimeters, divide height in centimeters by 100 to obtain height in meters.

Example: Weight = 68 kg, Height = 165 cm (1.65 m)

Calculation: 68 ÷ (1.65)² = 24.98

Pounds and inches

Formula: weight (lb) / [height (in)]² x 703

Calculate BMI by dividing weight in pounds (lbs) by height in inches (in) squared and multiplying by a conversion factor of 703.

Example: Weight = 150 lbs, Height = 5'5" (65")

Calculation: [150 ÷ (65)²] x 703 = 24.96

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