BMI Calculator
Compute BMI from height and weight, with both Korean (KSSO) and WHO classifications shown side by side. Ideal weight and BMR included.
- Underweight < 18.5
- Normal 18.5 – 22.9
- Overweight 23 – 24.9
- Obese I 25 – 29.9
- Obese II 30 – 34.9
- Obese III ≥ 35
- Underweight < 18.5
- Normal 18.5 – 24.9
- Overweight 25 – 29.9
- Obese I 30 – 34.9
- Obese II 35 – 39.9
- Obese III ≥ 40
How to Use
Pick metric (cm/kg) or imperial (ft·in/lb). Results update live.
See classifications from both KSSO (Korea — overweight at BMI 23+) and WHO (overweight at BMI 25+).
Ideal weight is computed at BMI 22. BMR is estimated from sex and age via Mifflin–St Jeor.
FAQ
How is BMI computed?
BMI = weight (kg) / height (m)². Example: 170 cm and 65 kg → 65 / 1.7² ≈ 22.5
Why do KSSO and WHO thresholds differ?
Studies show Asians face higher body-fat percentage and complication risk at the same BMI, so the Korean Society for the Study of Obesity uses 23/25 (overweight/obese) instead of WHO's 25/30.
What are BMI's limitations?
BMI doesn't separate muscle, fat, or bone. Athletes can have high BMI without obesity, and "skinny-fat" cases can be missed. Use it as a rough guide.
How is BMR estimated?
Mifflin–St Jeor: men = 10×kg + 6.25×cm − 5×age + 5, women = same with −161 instead of +5.
Is anything sent to a server?
No. All calculations happen in your browser; height and weight never leave the page.
