BMI Calculator
Calculate your Body Mass Index from height and weight and see which WHO category it falls into.
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How Is BMI Calculated?
Body Mass Index is weight in kilograms divided by height in metres squared: BMI = kg ÷ m². The WHO classifies results as: below 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, 30–34.9 obese (class I), 35–39.9 obese (class II) and 40+ obese (class III).
BMI is a quick population-level screening measure — it does not distinguish muscle from fat, so athletes may score "overweight" while being lean. For personal health decisions, consult a healthcare professional. This tool is informational and not medical advice.
Frequently Asked Questions
What is a normal BMI?
The WHO defines the normal range as 18.5 to 24.9. For example, a person 1.75 m tall is in the normal range between roughly 57 and 76 kg.
Is BMI accurate for athletes?
Not always. BMI cannot tell muscle from fat, so muscular people may be classified overweight despite low body fat. Waist circumference and body-fat percentage give a fuller picture.
Is BMI calculated differently for women?
The formula and WHO categories are the same for adult men and women. For children and teens, age- and sex-specific percentile charts are used instead.
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BMI Calculator