BMI Calculator

The BMI (body mass index) is a measurement of your healthy weightfor your height. Make use of this BMI calculator to check for the parents in your home.

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

This calculator should be utilized only by adult users (pregnant or lactating women should not base their decisions upon these BMI readings) however, no action should be taken based on its values beyond consulting a suitably qualified person such as a physician.

The calculator can give you an insight into how your weight compares to the norm for values. Body Mass Index (or BMI) is calculated by taking the weight of your body (in kg) divided by the square of your height (in meters) or BMI = Kg/M2.

Is Body Mass Index reliable?

Your BMI, or Body Mass Index, is the measure of your weight compared to your height. An accurate assessment of obesity is vital, as being obese or overweight significantly increases your risk of a range of medical conditions such as type 2 heart disease, diabetes, and cancer. As the levels of obesity or obesity increase, the spotlight has fallen onto BMI and its shortcomings as a measure of ideal weight for individual people and not for whole groups of people for whom 'averages' 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 adult people, BMI provides a reliable idea of your health risks. If your BMI exceeds 35, your weight is definitely putting your health at risk regardless of the reasons below. However, there are a few circumstances in which BMI could be over or underestimating these risks within the 25-35 BMI range. The most frequent ones are:

Children

Your doctor or health visitor can advise on the place your child should be on the 'centile charts' that are used to determine healthy weights for children.

Women who are pregnant

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

If you're extremely strong

BMI assumes you've an adequate amount of fat in your body including abdominal fat - belly fat that's located deep in your cavity, rather than underneath your skin. Fat in the abdominal area is more strongly linked to the risk of type 2 diabetes and heart disease than fat that is under the skin.

If you're exceptionally muscular your body fat could be lower than what is predicted by your BMI. However, this is only applicable to people who do extreme amounts of exercise - higher than average.

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

People of Asian origin are more likely to develop abdominal fat (fat within your stomach cavity and not under your skin) with lower levels of BMI than those of Caucasian origin. People with this pattern with weight gains are described as 'apples' rather than "pears" as per their body outline. It means that their health risk begin to increase at lower BMI as abdominal fat is directly related to the development of heart diseases and kind 2 diabetes.

The World Health Organisation has looked at the evidence and because of the differences between Asian populations and the different ethnic groups, it hasn't made any changes to the cut-offs. However, it does recommend that for public health purposes there are certain Asian groups are considered overweight If their BMI is between 22-25, and obese with a BMI of 26-31.

Older people (over 65, perhaps over 60)

As muscle mass tends decline and body fat tends to increase with age The BMI might not be an accurate indicator of body fat if over 60.

Alternative estimates of weight-related health dangers

If you believe that BMI does not accurately determine if you're obese or overweight taking a look at your abdominal circumference, waist-hip , or waist-height ratio can give you an accurate estimate.

Waist circumference

Your waist circumference should be measured at a half-way point between the bottom of your ribcage and at the highest point of the hip bone using a tape measure that is parallel to the floor. It is essential to breathe out when you measure. Male

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

Female

• Health risk increased - >80cm
• High health risk - >=88cm

Ratio of hip to waist

For a quick check of your waist to hip ratio, measure your waist circumference (as above) and then your hips' size at the widest point on your hips. Divide the circumference of your abdomen by your hip measurement for the ratio.

• For women, a waist-to- hip ratio that is greater then 0.85 is associated with a higher than average risk.
• For men who are overweight, a hip to waist ratio that is greater than 1.00 is associated with a greater than the average risk.

Waist to height ratio

A recent study that compared BMI, waist circumference, hip to waist ratio and waist to height ratio found that the most accurate method to determine your body fat mass was the waist-height relationship.

Measure your waist circumference as above, and then divide the measurement by your height. clearly both measurements must have either been in imperial (inches) or in metric (cm).

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

• 0.53 and more men
• 0.54 or greater for women

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

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