Understanding Body Mass Index (BMI)

Body Mass Index (BMI) is a universally recognized screening tool used by doctors and health professionals to categorize a person's weight relative to their height. While it does not measure body fat directly, it provides a quick and reliable indicator of whether you are in a healthy weight range.

How is BMI Calculated?

The mathematical formula for calculating BMI is quite straightforward. It is your weight in kilograms divided by the square of your height in meters.

If you use imperial units, the formula adjusts slightly to: BMI = 703 × (Weight in lbs) / [Height in inches]²

Example Calculation

Assume you weigh 70 kg and your height is 175 cm (which is 1.75 meters).

• Weight = 70
• Height = 1.75
• Height Squared = 1.75 × 1.75 = 3.0625
• BMI = 70 / 3.0625 = 22.8

According to the World Health Organization (WHO), a BMI of 22.8 places you securely in the "Normal Weight" category (18.5 to 24.9).

Frequently Asked Questions

What are the limitations of BMI?

Because BMI only considers total weight and height, it cannot distinguish between fat mass and muscle mass. Therefore, highly muscular athletes may have a BMI over 25 and be incorrectly classified as "overweight," despite having very low body fat. Older adults may also have a normal BMI but carry excessive, unhealthy visceral fat.