BMI Calculator

What this means

Body Mass Index is a screening tool that compares your weight to your height. The formula is kg ÷ m² — same in any country. The WHO classifies adult BMI into four bands: under 18.5 (underweight), 18.5–24.9 (normal), 25–29.9 (overweight), and 30+ (obese). It's a rough proxy for body fat; athletes with high muscle mass often score "overweight" without being so.

How to interpret your number

• Underweight — may suggest under-nutrition. Worth a chat with a doctor.
• Normal — associated with the lowest health risk in most studies.
• Overweight — slightly elevated risk for diabetes, heart disease. Not a crisis.
• Obese — meaningfully elevated risk; ideally addressed with a professional plan.

Limitations

BMI doesn't distinguish fat from muscle, ignores body shape and fat distribution, and was developed for adults (separate paediatric scales exist for children). Treat it as one input, not a verdict. For a more complete picture, see also our Body Fat % and Calorie calculators (coming soon).