# Body Mass Index (BMI) Calculator

Want to calculate body mass index (BMI)? Cool, try this calculator.

Body mass index (BMI) is a method of estimating your total body fat based on your weight and height. This BMI calculator determines your BMI using the standard formulas shown below:

Metric

BMI = W / (H x H)

where

BMI = Body Mass Index
W = Weight (in Kilograms)
H = Height (in Meters)

Imperial

BMI = (W x 703) / (H x H)

where

BMI = Body Mass Index
W = Weight (in Pounds)
H = Height (in Inches)

### World Health Organization BMI Classification Categories

For reference, the World Health Organization (WHO) breaks BMI down into the categories shown in the table below. When calculating your BMI it's important to understand that BMI is just a rough indicator, rather than an accurate measurement, of a person's body fat levels, and it is not always reliable as an indicator. If, for example, someone is heavy because they have a lot of muscle, rather than a lot of fat, they would have a high BMI despite having very little fat because the BMI calculation is based solely on a person's height and weight, without any true measurement of body fat levels. The BMI formula basically assumes that if you are heavy it's because you have excess fat, and not some other possible source of increased weight (such as having a lot of muscle). You can learn more about BMI here.

BMINutritional Status
Less than 18.5Underweight
From 18.5 to 24.9Normal
From 25.0 to 29.9Pre-obesity
From 30.0 to 34.9Obesity Class I
From 35.0 to 39.9Obesity Class II
40.0 and aboveObesity Class III