Body Mass Index Calculator

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What is Body Mass Index (or BMI)?

The Body Mass Index is an index calculated from an individual weight and height, designed to serve as a guide for human body fat (i.e., an individual "fatness" or "thinness"). Generally, an adult person with a BMI of 18.5 - 24.9 is regarded as having a normal or healthy weight for his or her height. A BMI lower than 17.5 is an indicator for anorexia nervosa, while a BMI higher than 30 is an indicator for obesity.

How to calculate BMI?

The BMI is calculated by dividing the individual body weight to the square of his or her height. Note that in order to calculate BMI, use either metric or imperial units for both mass and height.

To calculate BMI, simply type the values of the weight and height in either imperial (pounds and feet) or metric (kilograms and centimeters) units into the boxes provided in the body mass index calculator above and then click on the "calculate" button.

Formulas used to calculate BMI

SI (metric) units Imperial or US customary units

BMI = mass (kg) x 1002 / (height (cm))2

BMI = mass (lb) x 4.88 / (height (ft))2

BMI Chart - Undestanding Body Mass Index

BMI below 16.0Severely underweight
BMI = 16.0 to 18.5Underweight
BMI = 18.5 to 24.9Normal weight
BMI = 25 to 29.9Overweight
BMI of 30 or greater   Obese

These BMI ranges are only a rough indication to a person health as they do not take into account the person age, sex, or body fat. For example, an athletic person can have a high body mass index without necessarily being overweight.