BMI Calculator WHO standard
Body mass index and healthy weight range, instantly.
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⚠️ BMI does not reflect muscle mass — athletes and muscular builds may be misclassified as overweight. For accurate body composition, use DEXA, hydrostatic weighing, or BIA.
WHO BMI Classification
| BMI | Classification | Health Risk |
|---|---|---|
| Below 18.5 | Underweight | Reduced immunity, nutrient deficiency |
| 18.5 – 24.9 | Normal | Lowest |
| 25.0 – 29.9 | Overweight | Increased |
| 30.0 – 34.9 | Obese (Class I) | High |
| 35.0 – 39.9 | Obese (Class II) | Very high |
| 40.0 + | Obese (Class III, severe) | Extremely high |
Formula: BMI = weight (kg) ÷ height (m)². Source: WHO Global Database on Body Mass Index.
Healthy Weight Range by Height (BMI 18.5 – 24.9)
| Height | Underweight | Normal range | Overweight |
|---|---|---|---|
| 155 cm (5'1") | ~ 44.4 kg | 44.4 – 59.8 kg | 60.1 kg ~ |
| 160 cm (5'3") | ~ 47.4 kg | 47.4 – 63.7 kg | 64.0 kg ~ |
| 165 cm (5'5") | ~ 50.4 kg | 50.4 – 67.8 kg | 68.1 kg ~ |
| 170 cm (5'7") | ~ 53.5 kg | 53.5 – 71.9 kg | 72.2 kg ~ |
| 175 cm (5'9") | ~ 56.7 kg | 56.7 – 76.2 kg | 76.5 kg ~ |
| 180 cm (5'11") | ~ 59.9 kg | 59.9 – 80.7 kg | 81.0 kg ~ |
| 185 cm (6'1") | ~ 63.3 kg | 63.3 – 85.2 kg | 85.5 kg ~ |
height (m)² × 18.5 to × 24.9. Ideal weight (BMI 22) sits in the middle — at 175 cm, that's 67.4 kg.
Related Calculators
Frequently Asked Questions
How is BMI calculated?
BMI = weight (kg) ÷ height (m)². Example: 175 cm and 70 kg → 70 ÷ 1.75² = 22.86.
WHO classification: under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, 30+ obese.
Can I be obese with a normal BMI?
Yes. BMI does not distinguish muscle from fat. Athletes with high muscle mass may have high BMI
but low body-fat percentage. Conversely, 'skinny fat' individuals can have a normal BMI
but body-fat over 30%. For accurate body composition, use DEXA scan, hydrostatic weighing, or BIA.
How is ideal weight determined?
BMI 22 (the middle of the normal range) is commonly considered ideal weight. Formula:
height (m)² × 22. Example: 175 cm → 1.75² × 22 = 67.4 kg. This calculator
displays both the normal range (BMI 18.5–24.9) and the BMI 22 reference.
Does the same standard apply to children and the elderly?
No. Children are evaluated using growth percentile charts (CDC or WHO charts).
For the elderly, nutritional status is prioritized — some research suggests BMI 23–28 may be
optimal. This calculator is intended for adults aged 19+.
Why does the WHO use 25 as the overweight threshold?
The WHO BMI classification is based on global epidemiological data correlating BMI with mortality
and chronic disease risk. Some regional health bodies (e.g., Asia-Pacific, Korean Society for the
Study of Obesity) use a stricter threshold of 23 due to differences in body fat distribution.
References
Last reviewed: 2026-05-10
- WHO BMI classification — World Health Organization, Global Database on Body Mass Index
- Body composition gold standards — Kuriyan R. "Body composition techniques." Indian J Med Res 2018;148(5):648-658