Korea BMI Calculator KOSSO 2022 Guidelines · 8th ed.
Korea uses 23/25 BMI cutoffs (vs WHO's 25/30) — find out why, and where you stand. Korean clinics, insurance, and health checkups all measure you against the stricter KOSSO standard. Pair with ideal weight, % over ideal, and abdominal obesity for the full picture.
Add waist circumference for abdominal-obesity check (optional)
How it works
- BMI formula: weight(kg) ÷ height(m)². Example: 170 cm + 65 kg → 65 ÷ (1.7 × 1.7) = 22.5
- Korea KOSSO classes (5 levels):
- Underweight: BMI < 18.5
- Normal: 18.5 - 22.9
- Pre-obesity / Overweight (Korea): 23 - 24.9
- Class 1 obesity: 25 - 29.9
- Class 2 obesity: 30 - 34.9
- Class 3 obesity (severe): ≥ 35
- WHO international standard: 25 overweight / 30-34.9 class 1 / 35-39.9 class 2 / ≥40 class 3
- Ideal weight (Korea): height(m)² × 22 (men) or × 21 (women). Based on Korean cohort studies showing BMI 22 has the lowest mortality and disease incidence.
- % over ideal (PIBW): (actual − ideal) ÷ ideal × 100%. Within ±10% is the normal band.
- Abdominal obesity (optional): men ≥ 90 cm, women ≥ 85 cm — Korean Ministry of Health and KOSSO standard.
- Imperial conversion: ft·in × 2.54 → cm; lb × 0.453592 → kg. Toggle units anytime; values convert automatically.
⚠ Source: KOSSO 2022 Clinical Practice Guidelines, 8th edition (cutoffs unchanged since 2018). Same standard adopted by Korea's Ministry of Health and Welfare, KDCA, and the National Health Insurance Service.
FAQ
Why does Korea use lower BMI thresholds than WHO?
The Korean Society for the Study of Obesity (KOSSO) sets the overweight threshold at BMI 23 and obesity at 25, lower than WHO's 25/30. This is based on a 20-million-person Korean health insurance cohort showing that diabetes, hypertension, and dyslipidemia risk rises significantly from BMI 23 in Asians. The cutoffs aligned with WHO Asia-Pacific recommendations have remained unchanged in KOSSO's 2018, 2022, and 2024 guidelines.
Where in Korea will I face the 23/25 cutoff?
Korean company and national health checkups (건강검진) report your BMI against the 23/25 standard. Korean life and health insurance underwriting commonly applies surcharges starting BMI 25-30 and may decline coverage above 30. Hospital electronic records (EMR) at major institutions (Samsung, Asan, Severance) flag patients at BMI 23+. As a foreign resident with Korean coverage (NHI, expat insurance through 4대보험), this is the standard you'll be measured against.
What's the standard weight (표준체중) calculation?
Korean clinics use height(m)² × 22 for men and × 21 for women. This corresponds to the BMI value (22 or 21) associated with the lowest mortality and disease incidence in Korean cohort studies. For a 170 cm man, ideal weight is 1.7² × 22 = 63.6 kg. The "% over ideal" output on this page tells you how far you are from this reference.
Does BMI work for athletes, pregnant people, or seniors?
BMI overestimates body fat for muscular athletes (bodybuilders often score BMI 28-32 with single-digit body fat). For pregnant or breastfeeding people, use OB/GYN weight-gain charts instead. For seniors over 65, sarcopenia (muscle loss) means the same BMI hides higher body fat — pair BMI with waist circumference. The waist measurement field on this page captures abdominal obesity, the strongest predictor of cardiovascular risk in Asians.
What about waist circumference for abdominal obesity?
Korea uses ≥90 cm for men, ≥85 cm for women as abdominal obesity (Ministry of Health and Welfare). Even with normal BMI, exceeding the waist cutoff puts you in the "skinny-fat" / visceral obesity category, with cardiovascular risk equal to or higher than BMI-defined obesity. Measure at the midpoint between lowest rib and iliac crest (typically 1-2 cm above navel), at end of normal exhalation, with the tape touching skin without compression.