Page last updated at 08:21 GMT, Wednesday, 30 August 2006 09:21 UK

Calculate your body mass index

Body mass index graph

Doctors use the body mass index (BMI) as a simple way of assessing whether a patient needs to lose weight.

The calculation is based on comparing a person's weight with their body height. It applies equally to men and women.

You can quickly see the BMI assessment for your body on the chart above.

Alternatively, you can calculate your own BMI. Divide your weight in kilograms by the square of your height in metres, or divide your weight in pounds by the square of your height in inches, then multiply by 703.

You can also use the "What's your BMI?" link on the right to have the calculation performed for you.

A BMI of 25 to 29.9 is considered overweight and one of 30 or above is considered obese.

People with BMIs between 19 and 22 live longest. Death rates are noticeably higher for people with indexes 25 and above.

The BMI is not infallible. For instance, it is possible for a healthy, muscular athlete with very low body fat to be classified obese using the BMI formula.

If you are a trained athlete, your weight based on your measured percent body fat would be a better indicator of what you should weigh.


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