Understanding Body Mass Index (BMI)
Body Mass Index (BMI) is a simple, globally recognized mathematical formula used by doctors to broadly categorize human weight against height. It provides a standardized method to determine if an individual falls into a healthy weight range or is at cardiovascular risk due to being Underweight or Obese.
The Formula Behind It
The fundamental formula for BMI was developed in the 19th Century by Adolphe Quetelet. It natively runs entirely on Metric geometry:
BMI = kg / m²
Where:
- kg is a person's weight in kilograms.
- m² is their height in meters, squared.
If you are using empirical units (pounds and inches), the formula involves a conversion factor (703):
BMI = (lbs / in²) × 703
How to Use This Calculator
- Choose your units: Select whether you want to input your height and weight in Standard/Imperial (feet, inches, pounds) or Metric (centimeters, kilograms).
- Enter your height: Input your height in the designated fields.
- Enter your weight: Put your current weight in the weight field.
- Calculate: The system instantly calculates your BMI and presents your categorization (e.g., Normal, Overweight).
Real World Example
Example: Let's say John weighs 80 kg and is 1.80 meters tall.
His BMI calculation would be: 80 / (1.80 × 1.80)
80 / 3.24 = 24.69
John's BMI is 24.7, which places him in the Normal weight range.