How to Calculate BMI

Body mass index (BMI) is an important parameter in determining any kind of weight related problem. This article is a simple guide on how to calculate BMI on your own.

What is BMI?
Before we go into methods to calculate BMI, let us understand what do we exactly mean by body mass index and how is it useful. Body mass index (BMI), also known as 'Quetelet Index', after its inventor, Belgian polymath Adolphe Quetelet, is a statistical measure for comparing a person's height and weight. It is a ratio of weight to height, which is widely used all over the world to study problems related to abnormal weight issues. It is a way of objectively comparing a person's thinness or fatness. It does not measure the body fat of a person but only gives an idea about what the ideal body weight ratio for a person should be and how far away that person is from it. Though, it initially was suggested as an ideal statistical tool for studying height-weight ratio trends of a large population, later it gained popularity for studying weight problems as an individual tool.

Over a period of many years, medical researchers have worked out an ideal weight-height scale, which can be used to determine, whether a person is under weight, over weight or falls within the ideal weight range. Body mass index is directly proportional to weight of a person and inversely proportional to square of the height. Body mass index should not be taken as the ultimate judgment on whether a person is obese or underweight or for medical diagnosis, as it does not take fat content and its distribution over the body into consideration. It only serves to give a rough idea. According to statistically established scales, a person with a BMI in the range of 18.5 to 25 has normal or optimal weight, a person with BMI greater than 25 is overweight and one with BMI less than 18.5 is classified as underweight. BMI less than 17.5, is an indication of a person being extremely underweight. A BMI of 30 or greater than that indicates obesity, while 40 or greater than that indicates morbid obesity.

How to Calculate BMI in Simple Steps
Calculating the BMI can be beneficial in understanding where we stand relative to the optimally healthy body-weight ratio that we should have. Now let me explain the procedure of how to calculate BMI in simple steps.

Formula for Calculating BMI
Depending on what system of units one prefers, there are two formulas for calculating BMI. They are useful while calculating BMI using different units. The first one measures weight in pounds and height in inches. Even though this formula doesn't measure height in inches and weight in Kilograms, for sake of uniformity, it is designed in such a way, that it gives BMI in Kg/m². It is given by:

BMI (in Kg/m²) = [Weight (in Pounds) / (Height in inches ) x (Height in inches)] x 703

The factor of 703 ensures that the value of BMI comes out in Kg/m².

The second formula measures the BMI in Kg/m²; measuring height in meters and weight in kilograms. It is given as follows:

BMI (in Kg/m²) = (Weight in Kilograms) / (Height in Meters) x (Height in Meters)

Calculating BMI
Once you know the formula, you don't need to be an Einstein to figure out what to do next. Get a weighing scale and a measuring tape. Measure your height-weight in inches-pounds or meters-kilograms. In case you are measuring height in some other unit like feet, convert feet in to meters or inches. Plug-in the values in to the formulas given above according to the units used. Then with the aid of a calculator, you can easily calculate the BMI.

As you can see, how to calculate BMI is no big deal. All that you need to know is your weight and height accurately and plug in those values to get the BMI. BMI is a good indicator of how much you need to work on your body and it will help you in setting a weight loss target. Any weight loss program or weight gain program is best planned after consulting a doctor and a dietician. Plan your diet and exercise regimen according to their consultation.