This BMI (body mass index) calculator gives you an instant result from your weight and height, in kilograms and centimeters or in pounds, feet and inches. Besides the number, it shows the World Health Organization category and the weight range considered healthy for your height.
Everything is calculated in your browser, without sending your data anywhere. BMI is only a statistical reference for the adult population: it does not diagnose anything on its own and is best read alongside other health indicators.
How to use
- 1Choose your unit system: metric (kilograms and centimeters) or imperial (pounds, feet and inches).
- 2Enter your weight and height.
- 3Read your BMI, its WHO category and your healthy weight range.
- 4Check the visual gauge to see where your result falls at a glance.
What you can do
- Metric and imperial units
- WHO classification
- Healthy weight range for your height
How BMI is calculated
Body mass index is calculated by dividing weight in kilograms by height in meters squared (BMI = weight / height²). It is a simple formula, but widely used because it correlates with the risk of certain conditions at a population level.
What is a normal BMI?
The World Health Organization classifies adult BMI into these categories:
- Below 18.5: underweight.
- 18.5 to 24.9: normal weight.
- 25 to 29.9: overweight.
- 30 to 34.9: obesity class I.
- 35 to 39.9: obesity class II.
- 40 or above: obesity class III.
The limits of BMI
BMI does not distinguish muscle mass from fat mass, so it can overestimate the result for very muscular athletes. It is also not a suitable measure for children (who use age-specific percentile charts) or for pregnant people. If your result concerns you, talk to a healthcare professional, who will also weigh other factors like body composition, waist circumference and your medical history.
Frequently asked questions
What is a normal BMI?
For an adult, a BMI between 18.5 and 24.9 is considered a normal weight according to the World Health Organization.
How do I find my ideal weight from my BMI?
Your healthy weight range is whatever gives a BMI between 18.5 and 24.9. This calculator shows it directly as a range in kilograms or pounds once you enter your height.
Does BMI work for children or pregnant people?
Not in the same way. Children use age- and sex-specific percentile charts, and pregnancy changes weight for reasons BMI does not account for. In both cases, it is best to follow a healthcare professional's guidance.
I'm very muscular and my BMI is high — am I overweight?
Not necessarily. BMI does not tell muscle apart from fat, so people with a lot of muscle mass can get a high result without having excess body fat.
What's the difference between BMI and body fat percentage?
BMI only uses weight and height, while body fat percentage specifically measures how much fat you carry, usually through skinfold calipers, bioelectrical impedance or a DEXA scan. They are complementary measures, not interchangeable ones.