BMI Calculator
Body mass index from your height and weight, with the weight range that would put you in the healthy band.
Body mass index compares your weight with your height. It is a screening number, not a diagnosis: it says nothing about how much of your weight is muscle, where you carry fat, or how fit you are. Used sensibly it is still the quickest way to see whether your weight is in a range associated with fewer health problems.
How this is worked out
BMI is weight in kilograms divided by height in metres squared. The WHO bands for adults are: under 18.5 underweight, 18.5–24.9 healthy, 25–29.9 overweight, 30 and above obese. The Indian Ministry of Health and several Asian consensus statements use lower cut-offs because cardiometabolic risk starts climbing earlier in these populations — 23 for overweight and 25 for obesity — which is what the toggle above switches to.
BMI misreads two groups in particular. Muscular people get pushed into "overweight" by muscle that carries no risk at all, and older adults who have lost muscle can sit in the healthy band while carrying a lot of fat. If your BMI surprises you, a waist measurement and a waist-to-height ratio usually tell you more.
BMI is not valid for children and teenagers — their BMI has to be read against age and sex percentiles. Use the child BMI calculator for anyone under 20.
This calculator runs entirely in your browser. Nothing you enter is transmitted to us, saved on our servers, or shared with anyone.
Common questions
What is a healthy BMI?
For most adults, 18.5 to 24.9. On the Asian-Indian cut-offs used widely in India, the healthy band is 18.5 to 22.9.
Is BMI accurate for athletes?
Often not. BMI cannot tell muscle from fat, so a trained athlete can register as overweight while carrying very little fat. Body fat percentage or a waist measurement is a better guide in that case.
Does BMI change with age?
The adult bands do not change with age, but their meaning does. Some research suggests a slightly higher BMI is not harmful after about 65, while muscle loss can hide a high body fat percentage behind a normal BMI.