BMI calculator.

Your body mass index in one tap — with the WHO category it lands in and, just as important, a straight answer about what that number does and doesn’t mean.

Categories follow the WHO adult cut-offs: below 18.5 underweight, 18.5–24.9 healthy range, 25–29.9 overweight, 30 and above obesity. BMI is a population-level screening number, not an individual diagnosis — guidance, not medical advice.

What BMI can — and can’t — tell you

BMI does one thing well: across large groups of people, it correlates with health risk strongly enough that researchers and doctors use it as a quick first filter. That’s the whole job. It was never designed to judge an individual body, and it fails predictably in two directions:

• It can’t see muscle. BMI only knows height and weight, so a lean, well-trained person often lands in the “overweight” band while carrying very little fat. If you strength train regularly, your number will read high relative to how you actually look and feel.
• It can’t see where fat sits. Two people with identical BMIs can carry weight very differently, and fat stored around the organs matters more for health than fat under the skin. A tape measure at the waist adds context BMI simply doesn’t have.

So treat BMI as one data point among several — alongside waist measurement, how your clothes fit, energy levels and the trend on the scale. If your number sits above the healthy range and you want to change it, the lever is a moderate calorie deficit held over time: the weight-loss timeline calculator turns a goal weight and a sustainable pace into a realistic date.