What your BMI means
Body Mass Index estimates body fat from your weight and height (weight in kilograms divided by height in metres squared). This calculator uses the standard World Health Organization categories for adults:
- Below 18.5 — underweight
- 18.5 to 24.9 — normal weight
- 25 to 29.9 — overweight
- 30 and above — obese
Frequently asked questions
Is BMI accurate for everyone?
It's a quick screening tool, not a diagnosis. Because it only uses weight and height, it can't tell muscle from fat, so very muscular people may read as “overweight” and it's not designed for children or pregnancy. Treat it as a general guide.
What's the difference between metric and imperial?
Just the input units — metric takes kilograms and centimetres, imperial takes pounds and feet/inches. The calculator converts imperial values internally, so the BMI is the same either way.
How do I lower or reach a healthy BMI?
A BMI in the 18.5–24.9 range is generally considered healthy for adults, but the right target depends on your body and health. Speak with a doctor or dietitian before making significant changes.
Is my information saved or uploaded?
No. The calculator runs entirely in your browser. Nothing you enter is stored or sent to a server.