BMI Calculator Online Free
Calculate body mass index in metric or imperial units and see the standard category.
Healthy weight range. BMI is a rough screening figure, not a diagnosis.
How to use this tool
- 1Choose metric or imperial units.
- 2Enter your height.
- 3Enter your weight.
- 4Read your BMI value and the category it falls into.
About this tool
Body mass index divides weight by the square of height to give a single number that describes weight relative to size. The World Health Organization bands it into underweight below 18.5, healthy weight from 18.5 to 24.9, overweight from 25 to 29.9, and obese at 30 and above. It is used widely because it needs only two easily measured values and works reasonably well across large populations. As an individual measure it has real limits: it does not distinguish muscle from fat, so athletes often read as overweight, and it does not account for age, sex, body composition or where fat is distributed, which matters more for health risk than the total. Treat the number as one rough indicator among several, not a diagnosis.
Frequently Asked Questions
Is BMI accurate for everyone?
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No. It can overestimate body fat in muscular people and underestimate it in older adults who have lost muscle. It is a population-level screening measure.
What is a healthy BMI range?
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The standard healthy range is 18.5 to 24.9, though clinical guidance varies by population and by individual circumstances.
Is this medical advice?
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No. This calculator is for general information only. Speak to a doctor about anything concerning your health.