BMI Calculator

Body Mass Index is calculated by dividing your weight in kilograms by the square of your height in meters:

BMI = weight (kg) / height (m)²

For example, a person who is 170 cm tall and weighs 68 kg has a BMI of 68 ÷ 1.70² = 23.5. The World Health Organization groups adult BMI into four broad categories: below 18.5 is considered underweight, 18.5 to 24.9 is the normal or healthy range, 25 to 29.9 is overweight, and 30 or above is classified as obese. These thresholds are the same for adult men and women, which is part of what makes BMI such a widely used screening tool in clinics, insurance assessments, and public health studies.

BMI is a useful population-level screening measure, but it is not a diagnosis. It cannot distinguish between muscle and fat: a muscular athlete may register as overweight despite very low body fat, while an older adult with low muscle mass may have a normal BMI yet carry excess fat. It also does not capture where fat is stored — abdominal fat carries higher health risks than fat stored elsewhere, which is why measures like waist circumference and waist-to-height ratio are often used alongside BMI. Additionally, some health bodies recommend lower thresholds for certain populations; for example, health risk in South Asian populations may begin at a BMI as low as 23.

Treat your BMI as a starting point for a conversation with a healthcare professional, not a verdict. If your result falls outside the normal range, a doctor can assess the fuller picture, including body composition, blood markers, lifestyle, and family history.