BMI Calculator
Enter your weight and height to get your body mass index (BMI), the World Health Organization category it falls into, and the healthy weight range for your height. Works with kg/cm or pounds/feet.
BMI is a screening measure — it does not distinguish muscle from fat. Talk to a health professional for a full assessment.
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- Choose your preferred units (kg/cm or pounds/feet).
- Enter your weight and height — the result updates instantly.
- Check your BMI, the WHO category and the healthy weight range.
- Remember: BMI is a screening tool, not a diagnosis.
What BMI means
Body Mass Index divides your weight by your height squared (kg/m²). The World Health Organization classifies results as: below 18.5 underweight; 18.5–24.9 normal; 25–29.9 overweight; 30–34.9 obesity class I; 35–39.9 class II; 40+ class III. It is the most used population screening measure in the world because it needs only a scale and a measuring tape.
What BMI does not tell you
BMI cannot tell muscle from fat: athletes often score "overweight" with low body fat, and older adults can have a "normal" BMI with low muscle mass. It also ignores where fat is stored — abdominal fat carries more risk. That is why doctors combine BMI with waist circumference, body composition and blood work. Treat the number here as a starting point for a conversation with a health professional, not as a verdict.
Using the healthy range
The range shown above is simply the weight that would put your BMI between 18.5 and 24.9 for your height — a practical target zone. Sustainable changes (0.5–1 kg per month) beat crash diets in virtually every long-term study.
Frequently asked questions
What is a normal BMI?
Between 18.5 and 24.9 kg/m², according to the World Health Organization. Below 18.5 is underweight and 25 or more is overweight.
Is BMI accurate for athletes?
Not very — muscle weighs more than fat, so muscular people often score as "overweight" while being lean. Body composition tests are better in that case.
Is the calculation different for men and women?
The standard WHO formula and ranges are the same for adults of both sexes. Children and teens use age-specific percentile charts instead.
Is my data sent anywhere?
No. The calculation happens entirely in your browser — your weight and height never leave your device.