BMI Calculator
Judged by the Chinese adult standard (24/28 cut-offs), not the WHO international standard.
Underweight <18.5 | Normal 18.5–23.9 | Overweight 24–27.9 | Obese ≥28. BMI does not distinguish muscle from fat; not applicable to athletes or pregnant women.
When to use it
- Your health check lists a BMI number and the word “overweight” but no ranges, and you want to know whether the 24 cut-off is the one being used.
- You are starting a weight-loss or weight-gain plan and want a target range from the 18.5–23.9 band instead of chasing one number on the scale every day.
When not to
- You are in a muscle-building phase: muscle is denser than fat, so a BMI above 25 does not mean excess fat — track body-fat percentage, waist circumference and lifting numbers instead.
- You are pregnant or breastfeeding, or under 18: the 24/28 adult cut-offs do not apply. Use the antenatal weight-gain curve, or age-and-sex BMI percentiles for children.
Height and weight are calculated in your browser only — nothing is uploaded, saved or kept after you close the tab, because body measurements are private. Limits: BMI is weight divided by height squared, not a measure of fat; it cannot separate muscle from fat, does not apply in pregnancy or under 18, and athletic builds can read as overweight. China's 24/28 cut-offs differ from WHO's 25/30.
Frequently asked
Why does China use a different BMI standard from WHO?
The two sets of cut-offs come from different populations, not from different arithmetic. WHO uses 18.5 / 25 / 30 — normal 18.5–24.9, overweight 25–29.9, obese 30 and above. China's adult standard uses 18.5 / 24 / 28 — normal 18.5–23.9, overweight 24–27.9, obese 28 and above. The 24 and 28 lines come from a 2002 analysis by the Working Group on Obesity in China (WGOC): at the same BMI, high blood pressure and diabetes risk rose at lower levels in Chinese cohorts, so the overweight line moved down to 24 and obesity to 28. A BMI of 24.5 is overweight in China and normal under WHO; Japan's Obesity Society sets obesity at 25. Check which standard a report, insurer or paper is using.
How is the healthy weight range worked out?
By inverting the same formula: lower bound 18.5 × height(m)², upper bound 23.9 × height(m)². At 1.73 m, 18.5 × 1.73² ≈ 55.4 kg and 23.9 × 1.73² ≈ 71.5 kg, so the range is 55.4–71.5 kg. The upper bound is 23.9 rather than 24 because the normal band is written up to 23.9; from 24.0 you are overweight. The page shows BMI to one decimal but classifies the unrounded value: 23.96 displays as 24.0 and is still normal, while 24.04 also displays as 24.0 and is already overweight.
My BMI is normal but my waist is large — am I healthy?
Not necessarily. BMI sees total weight, not where fat sits. China's adult standard uses waist circumference for central obesity: 90 cm or more in men and 85 cm or more in women, with 85–89.9 cm (men) and 80–84.9 cm (women) as the pre-obese band. Someone with a BMI of 22 and a 95 cm waist can carry more metabolic risk than someone at BMI 26 with an 80 cm waist. Read BMI, waist and body-fat percentage together.