Body Mass Index (BMI) is the number your doctor, gym and health apps all seem to mention. It's a quick way to gauge whether your weight sits in a healthy range for your height — and you can find yours in seconds with our BMI calculator.
How BMI is calculated
BMI divides your weight by the square of your height. In metric units that's weight (kg) ÷ height (m)². So someone who is 1.75 m tall and weighs 70 kg has a BMI of about 22.9. You don't need to do the maths by hand — enter your numbers and the calculator does it instantly, in metric or imperial.
What the categories mean
- Under 18.5 — underweight
- 18.5–24.9 — healthy weight
- 25–29.9 — overweight
- 30 and above — obese
Where BMI falls short
BMI is a screening tool, not a diagnosis. Because it only uses height and weight, it can't tell muscle from fat — very muscular people often read "overweight" despite low body fat. For a fuller picture, pair it with our body fat calculator and an ideal weight range.
Putting it to use
If your BMI is outside the healthy range, use it as a starting point for a conversation with a professional — not a verdict. And if you're managing your weight, our calorie calculator can help you set a daily target.