BMI Calculator
Check your Body Mass Index in metric or imperial units — result and category update as you type. Nothing is sent anywhere.
Underweight <18.5 · Normal 18.5–24.9 · Overweight 25–29.9 · Obese ≥30
What does BMI mean?
Body Mass Index is a quick screening measure estimated from your weight relative to your height: BMI = weight (kg) ÷ height (m)². The World Health Organization categories above apply to most adults aged 20 and over. It is a useful first signal — but it does not distinguish muscle from fat, so athletes often score "overweight" while being perfectly healthy.
Frequently asked questions
Is BMI accurate for everyone?
It is a population-level screening tool, not a diagnosis. It tends to overestimate body fat in muscular people and underestimate it in older adults who have lost muscle. For children, use age- and sex-specific percentile charts instead.
Does this tool store my weight or height?
No. The calculation runs entirely in your browser — your numbers never leave your device.