Before you start to investigate whether or not you need to lose weight, you need to be able to calculate your body mass index (BMI). Your body mass index is an indicator of the amount of fat in your body and it applies to all adults male and female, irrespective of age. The old height weight range does not give an indication of the amount of fat that is stored in your body.

It is a statistical tool, an easy calculation to work out your weight range in relation to other peoples. There are two ways of calculating the BMI, in either metric or imperial measurements. There are several automatic body mass calculators on the Web and a search within Google or your favourite search engine will reveal all. Please feel free to use our BMI calculator.

However, for those of you that would like to work it out for yourself the calculation is not rocket science and the formula is illustrated below. A calculator will make the job easier and Microsoft's calculator can be found here, go to

Start > Programmes > Accessories> Calculator.

To work out your BMI in metric measurements:

Calculate your height in meters and record your weight

Example:

Weight = 73kg
Height = 1.72 m
The calculation is 73 / (1.72 x 1.72)
1.72 x 1.72 = 2.9584
73 / 2.9584 = 24.67

To work out your BMI in Imperial measurements:

To calculate the body mass in pounds you need your weight in pounds and your height in inches. The formula is the weight in pounds times the height in inches squared, and then multiplied by a conversion figure of 703.

Example:

Weight = 155lbs and the height is five feet four inches which is equal to 64 inches:

Weight = 155 lbs
Height = 64 inches
The calculation is {155 / (64 x 64) x 703}
64 times 64 = 4096
155 / 4096 x 703 = 26.60

To read and interpret the BMI Weight
Below 18.5: Underweight
18.5 - 24.9: Normal Weight
25.0 - 29.9: Overweight
30.0 and Above: Clinically Obese

For example, here are the weight ranges, the corresponding BMI ranges, and the weight status categories for a sample height. The table illustrates a Caucasian male, of five feet nine and various example weights.

Height	Weight range in lbs	Calculated BMI	Weight status
5 feet 9 inches	124lbs or below	18.5	Underweight
5 feet 9 inches	125 lbs to 168 lbs	18.5 to 24.9	Normal
5 feet 9 inches	169 lbs to 202 lbs	25.0 to 29.9	Overweight
5 feet 9 inches	203 lbs or above	30 and above	Clinically obese

The calculation with children is age and sex specific and it is recommended that you use an automatic converter.