Obesity is most commonly calculated using Body Mass Index (BMI). BMI is calculated by dividing a person’s weight in kilograms by his or her height in square meters. Overweight (pre-obese) starts with a BMI of 25.

BMI levels for overweight and obesity are set by the World Health Organization. The World Health Organization (WHO) defines “overweight” as a BMI equal to or more than 25, and “obesity” as a BMI equal to or more than 30. An adult with a BMI of 30 or greater is clinically obese.

Obesity Table

Category
BMI (Kg/m²)
 Health Risk
Under weight Below 18.5 Light
Normal weight 18.5 – 24.9 Healthy
Over weight 25.0 – 29.9 Light
Obese Level I 30.0 – 34.9 More serious
Obese Level II 35.0 – 39.9 Serious
Morbidly Obese 40.0 and above Very serious


To Calculate your  Body Mass Index check following page:

International BMI Calculator

For adults 20 years old and older, BMI is interpreted using standard weight status categories that are the same for all ages and for both men and women. BMI is used differently for children. It is calculated the same way as for adults, but then compared to typical values for other children of the same age. For children and teens, the interpretation of BMI is both age- and sex-specific. According to the World Health Organization at least 20 million children under the age of 5 years are overweight globally in 2005.

To calculate the BMI for Children check:

Children BMI Calculator