What Is BMI and How Is It Calculated?

Body Mass Index (BMI) is a screening tool that estimates body fat based on your height and weight. It was developed by Belgian mathematician Adolphe Quetelet in the 1830s and remains one of the most widely used health metrics globally.

The Formula

BMI = weight (kg) / height (m)^2

In imperial units: BMI = (weight in lbs x 703) / (height in inches)^2

BMI Categories (WHO Standards)

• Below 18.5 -- Underweight
• 18.5 to 24.9 -- Normal weight
• 25.0 to 29.9 -- Overweight
• 30.0 and above -- Obese

Limitations of BMI

BMI does not distinguish between muscle and fat. A muscular athlete can have a high BMI while carrying very little body fat. It also does not account for age, sex, bone density, or fat distribution. Waist circumference and body fat percentage are more accurate indicators for many people.

BMI is best used as a starting point for a broader health conversation, not a definitive diagnosis. If your BMI falls outside the normal range, consult a healthcare provider for a more complete assessment.