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BMI Calculator
Enter your height and weight to see your Body Mass Index, the WHO category, and the healthy weight range for your height.
This tool provides a general estimate only and is not a substitute for professional medical advice; talk to a doctor about decisions affecting your personal health.
How is BMI calculated?
Body Mass Index comes from a simple formula: weight in kilograms divided by height in meters squared. For someone 170 cm (1.7 m) tall weighing 70 kg, BMI = 70 ÷ (1.7 × 1.7) ≈ 24.2. The World Health Organization splits the result into four bands: under 18.5 is underweight, 18.5–24.9 is normal, 25–29.9 is overweight, and 30 or above is obese. These bands were built for the general adult population and underpin most public-health and insurance screening.
BMI isn't a perfect measure, though — it only compares total weight to height and can't tell fat from muscle. A heavily muscled athlete can post a high BMI without carrying excess fat, while someone with low muscle mass and high body fat can land in the "normal" range. That's why it's worth reading BMI alongside other measures like body fat percentage rather than on its own. Children, teens, pregnant women and older adults need growth charts or other age-specific measures instead.
Frequently asked questions
What is BMI and how is it calculated?
Body Mass Index (BMI) is weight in kilograms divided by the square of height in meters. It's a quick estimate of weight relative to height.
Is BMI accurate for everyone?
Not entirely. BMI doesn't distinguish between fat and muscle, so it can be misleading for muscular athletes, older adults, children and pregnant women.
How is the healthy weight range calculated?
This tool multiplies the normal BMI range (18.5–24.9) by the square of your height to show the matching weight range.
What are the WHO BMI categories?
Under 18.5 is underweight, 18.5–24.9 is normal, 25–29.9 is overweight, and 30 and above is considered obese.