BMI Calculator

What is BMI?

Body Mass Index (BMI) is a measure that relates weight to height to assess whether a person has a healthy weight. It was developed by Belgian statistician Adolphe Quetelet and is used by the World Health Organization (WHO) as an international reference standard.

How is BMI Calculated?

The BMI formula is: weight (kg) / height (m)². For example, if you weigh 70 kg and are 1.70 m tall, your BMI is 70 / (1.70 x 1.70) = 24.2, which is classified as normal weight. When using imperial units, the formula is: (weight in lbs / height in inches²) x 703.

WHO BMI Classification Table

Underweight: BMI below 18.5. Normal weight: 18.5 to 24.9. Overweight: 25 to 29.9. Obese Class I: 30 to 34.9. Obese Class II: 35 to 39.9. Obese Class III: 40 or higher.

Frequently Asked Questions

Does BMI apply equally to men and women?

The formula is the same, but interpretation may vary. Women tend to have a higher body fat percentage than men at the same BMI. It is recommended to supplement with other measurements such as waist circumference or body fat percentage.

What is the ideal BMI?

According to the WHO, a BMI between 18.5 and 24.9 is considered normal weight. However, the ideal BMI can vary depending on age, sex, and body composition. Athletes, for example, may have a higher BMI due to muscle mass without being overweight.

What are the limitations of BMI?

BMI does not distinguish between muscle mass and fat mass, does not account for bone density, age, or sex differences, and does not indicate where body fat is distributed. It should be used as a screening tool, not a diagnostic measure.