BMI Calculator
Calculate your Body Mass Index and check your health status
About BMI Calculator
Body Mass Index compares your weight to your height to place you in a broad weight category. It is a screening indicator used at population level — a starting point for a conversation, not a measure of health or body fat.
How BMI is calculated
In metric units BMI is weight(kg) ÷ height(m)². In imperial units the same relationship needs a conversion factor: weight(lb) ÷ height(in)² × 703. The World Health Organization bands for adults are: under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, and 30 or above obesity.
Where BMI is misleading
It measures a ratio, not composition, so it cannot distinguish muscle from fat. Athletes and heavily muscled people are routinely classified as overweight while carrying very little fat; older adults who have lost muscle can sit in the normal band while carrying a lot. It also ignores where fat is distributed, and abdominal fat carries more metabolic risk than the same weight elsewhere. The standard adult bands do not apply to children, teenagers, pregnant people, or to everyone equally across ethnic groups — several health bodies use lower thresholds for people of South and East Asian descent.
Medical note
BMI is a screening number, not a diagnosis, and this calculator is not medical advice. A single figure cannot assess your health: waist circumference, blood pressure, blood glucose, lipids, activity, diet and family history all matter more together than BMI does alone. Discuss any concern about your weight with a doctor, who can interpret the number in context rather than in isolation.