BMI Formula  How do you calculate your BMI?
Body Mass Index is a simple calculation using a person's height and weight. The formula is BMI = kg/m^{2} where kg is a person's weight in kilograms and m^{2} is their height in meters squared. A BMI of 25.0 or more is overweight, while the healthy range is 18.5 to 24.9. BMI applies to most adults 1865 years.
So, what units are used to measure BMI?
Body mass index (BMI) is obtained by measuring a subject's weight in kilograms (kg) or pounds (lb) and the subject's height in meters (m) or inches (in). The BMI is then calculated by dividing the subject's weight by the square of his/her height. Therefore, weight is normalized for height.
BMI Formula by Adolphe Quetelet 

It was developed by Belgium
Statistician Adolphe Quetelet approximately 150 years ago. This was
before the era of electronic calculators; any formula used to indicate
weight status needed to be easy for physicians to manually calculate.

Adolphe Quetelet: Creator Of The BMI Formula 
How To Calculate BMI 

Metric Method 
Imperial (US) Method 