BMI Calculator

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

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

The calculator should only be employed only by adult users (pregnant or lactating ladies should not rely in these BMI readings), and no action should be determined based on the results other than consulting an appropriate professional such as a doctor.

The calculator will give you an the information you need to know how your weight compares to typical values. Body Mass Index (or BMI) is calculated by taking the weight of your body (in kg) times the height of your square (in metres) or BMI = Kg/M2.

Is Body Mass Index reliable?

Your BMI is also known as Body Mass Index, is an index of your weight in relation to your height. The accuracy of your assessment of obesity is crucial, since being overweight or obese increases your risk of developing a variety of medical conditions like type 2 diabetes, heart disease and cancer. As levels of excess weight or obesity increase the spotlight has shifted the spotlight on BMI and its flaws as a gauge of the ideal weight for people and not for whole groups of people for whom "averages" will 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 gives a good idea of your health risks. If your BMI is above 35, you are most likely to put your health at risk regardless of the variables below. However, there are a few circumstances in which BMI could be over or underestimating this risk within the 25 to 35 BMI range. The most frequent ones are:

Children

Your GP or health visitor can help you determine what your child's position is 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're extremely strong

BMI assumes you have equal amounts of body fat, including abdominal fat - belly fat that's located deep in your cavity rather than under your skin. In fact, abdominal fat is more closely associated with the risk of type 2 heart disease and diabetes than fat that is under the skin.

If you're very muscular, your level of body fat may be lower than expected by your BMI. However, this is only applicable to those who exercise at extreme amounts of exercise - much more than average.

If you're of Asian or Asian descent, you're in the right place.

People of Asian heritage are more susceptible to accumulate abdominal fat (fat that is located deep in your stomach cavity and not under your skin) at lower BMI than those of Caucasian origin. People who exhibit this pattern of weight gain are described as 'apples' instead of "pears" as per their body outline. This means their health risks increase when they have a lower BMI due to the fact that abdominal fat is directly linked to development of heart disease and kind 2 diabetes.

The World Health Organisation has looked at the evidence, and because there is a wide variation between Asian populations It hasn't changed the cut-off points. But, it does suggest that for public health purposes there are certain Asian groups should be considered overweight when their BMI is between 22 and 25 or obese with BMIs of 26-31.

People who are older (over 65, possibly 60)

Because muscle mass tends decline and body fat tends to rise in older people It is possible that BMI is not an accurate reflector of body fat if older than 60.

Alternative estimates of weight-related health dangers

If you feel BMI may not accurately tell you if you're obese or overweight by measuring your abdomen circumference, waist, or waist ratio could provide you with an accurate figure.

Waist circumference

Your waist circumference should be measured halfway between the bottom of your ribcage and above your hip bones with the tape measure parallel to the floor. The person breathing out must be present as you measure. Male

• Higher risk of developing health issues - >=94cm
• Health risk for high-risk patients - > 102cm

Female

• Risk of increased health - >80cm
• Health risks for the elderly >= 88cm

The ratio of waist to hip

To check your waist to hip ratio, measure the circumference of your waist (as above), and your hip size in the widest portion of your hips. Divide the circumference of your abdomen by your hip measurement to get a ratio.

• For women, a waist to hip ratio of more that 0.85 is associated with greater than average risk.
• In men the waist-to-hip ratio greater over 1.00 is associated with a greater than average risk.

Waist to height ratio

A study conducted recently comparing BMI the waist circumference, hip-to-waist ratio, and the waist-to-height ratio discovered that the best method of predicting your whole-body fat level was waist-height ratio.

Take your waist circumference measurements as above and simply divide the measurement 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 as a waist-to-height ratio that is:

• 0.53 or higher for males
• 0.54 plus for females

Abdominal obesity was defined by a waist-to-height proportion of 0.59 or more.

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