BMI Calculator

BMI (body mass index) is a measure of whether you're a healthy weightfor your height. Make use of the BMI calculator to determine whether your parents are healthy.

For children, visit Weight Concern's Child page and the young individual's body mass index (BMI) tool. Imperial

This calculator should be employed in the case of adult (pregnant or lactating women shouldn't rely in these BMI readings), and no action should be made based on its results other than to consult a suitably qualified person such as a doctor.

The calculator will give you the idea of how your weight is compared to normal values. Body Mass Index (or BMI) is calculated as your weight (in kg) per square of height (in meters) or BMI = Kg/M2.

Is Body Mass Index reliable?

Your BMI is also known as Body Mass Index, is the measure of your weight as a percentage of your height. Accurate assessments of obesity are essential, as being overweight or obese increases the risk of contracting a variety of medical conditions like type 2 diabetes, heart disease and cancer. When the prevalence of overweight or obesity rise The spotlight has fallen the spotlight on BMI and its weaknesses as a measure of optimal weight for individuals, rather than whole populations of people for whom "averages" do apply.

"Some people naturally have a larger frame than others. But this causes quite a small variation in weight and is accounted for in the range of healthy BMI. There is really no such thing as someone who is big-boned. " Dr Jan Sambrook, How to lose weight in a healthy way

For most individuals, BMI provides a reliable estimation of your health risks. If your BMI exceeds 35, you're certainly putting your health at risk regardless of the risk factors below. But, there are situations where BMI may underestimate or overestimate the risk in the 25-35 BMI range. The most common are:

Children

Your physician or health visitor can help you determine the position of your child on the "centile charts" which are used to calculate the weights that are healthy for children.

Pregnant women

Usual BMI estimates do not apply if you're pregnant.

If you are very muscular

BMI assumes you've some body fat, including intra-abdominal fat, fat deep inside your stomach cavity instead of under your skin. Fat in the abdominal area is more closely associated with the risk of type 2 diabetes and heart disease than fat that is under the skin.

If you're exceptionally muscular the amount of body fat may be lower than what is predicted by your BMI. But, this is only applicable to those who engage in intense exercise far more than average.

If you're of Asian Origin, you will be able to identify yourself.

People of Asian origin are prone to develop intra-abdominal fat (fat deep inside your stomach cavity and not under your skin) with lower BMI levels than those of Caucasian origin. The people who have this type that gain weight are referred to as "apples" rather than "pears" as per their body outline. It means that their health risk increase with a lower BMI as the intra-abdominal fat is directly linked with the development of heart disease, and types 2 diabetes.

The World Health Organisation has looked at the evidence and because of the varying characteristics between Asian populations however, they haven't yet officially altered the cut-off points. However, it has recommended that for public health purposes, some Asian groups are considered overweight if their BMI is 22-25 and obese if they have BMIs between 26 and 31.

People who are older (over 65, possibly 60)

Because muscle mass tends to shrink and body fat tends to rise in people over 60 however, BMI may not be an accurate reflection of body fat if older than 60.

Alternative estimates of health-related weight dangers

If you think that your BMI might not accurately represent whether you are overweight or obese, measuring your abdominal circumference, waisthip or waist ratio could provide you with a more realistic estimate.

Waist circumference

The waist circumference is measured half way between the bottom of your ribcage and high-top of your hip bones with the tape measure in line with the floor. The person breathing out must be present when you measure. Male

• Higher risk of developing health issues - >=94cm
• High risk of health - > 102cm

Female

• Higher risk of health-related illness - >80cm
• Health risks for the elderly >= 88cm

Ratio of hip to waist

For a quick check of your waist to hip ratio, measure how wide your waist is (as above) and then your hips' size at the widest portion the hips. Divide your abdominal circumference in relation to your measurements of your hips to determine an approximate ratio.

• For women, a waist-to- hip ratio of more by 0.85 is associated with greater than average risk.
• In men in men, a hip-to-waist ratio of more in excess of 1.00 is associated with higher than average risk.

Ratio of waist to height

A recent study on the relationship between BMI along with waist circumference, waist-to-hip ratio and the ratio of waist to height found the most reliable method of predicting your total body fat mass was the waist-height relationship.

Find your waist circumference using the method above and simply divide it by your height - quite obviously, both measurements should have either been in imperial (inches) or the metric (cm).

The definition of obesity for the whole body is by a waist-to-height ratio of:

• 0.53 or more for males
• 0.54 or more for women

Abdominal obesity was defined by the waist-height ratio to 0.59 or greater.

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