Calculate your Body Mass Index (BMI) instantly. Find out if your weight is in the healthy range according to WHO guidelines.
The Body Mass Index (BMI) is a widely used screening tool that estimates body fat based on height and weight. Our free BMI calculator works for both metric (kilograms and centimetres) and imperial (pounds, feet and inches) measurements, and gives you an instant result with your BMI category according to WHO (World Health Organisation) guidelines.
Simply enter your weight and height, click calculate, and you'll see your BMI number along with your category — Underweight, Normal weight, Overweight, or Obese — plus a description of what it means for your health.
The World Health Organisation classifies BMI into four main categories for adults over 18. A BMI below 18.5 is considered underweight, which may indicate nutritional deficiency or other health issues. A BMI between 18.5 and 24.9 is considered normal or healthy weight. A BMI between 25 and 29.9 indicates overweight. A BMI of 30 or above is classified as obese, which is further divided into Class I (30–34.9), Class II (35–39.9) and Class III (40+).
While BMI is a useful screening tool, it has important limitations. It does not directly measure body fat — it cannot distinguish between muscle mass and fat. A highly muscular athlete may have a high BMI without being overweight in terms of body fat. BMI also doesn't account for age-related changes in muscle and fat distribution, gender differences in body composition, or where fat is stored in the body (abdominal fat is more dangerous than fat in other areas).
For a more complete picture of health, BMI should be considered alongside other measurements such as waist circumference, waist-to-height ratio, and body fat percentage. Always consult a healthcare professional for personalised health advice.