Adult BMI calculator
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Enter height in centimetres (1.70 m = 170 cm). For adults.
BMI
Enter your height and weight.
BMI does not directly measure body fat or health problems. Adult categories should not be applied unchanged during pregnancy, the postpartum period, substantial oedema or growth.
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Formula, categories and sources
Method
BMI = weight (kg) ÷ height (m)². Height is converted from centimetres to metres once. Categories use the unrounded value, not the displayed two-decimal result.
Example
At 170 cm and 65 kg: 65 ÷ 1.70² = 22.491… → BMI 22.49. Both WHO and JASSO place this in the normal weight range.
Adult categories
| BMI (kg/m²) | WHO | JASSO |
|---|---|---|
| Below 18.5 | Underweight | Underweight |
| 18.5 to below 25 | Normal range | Normal weight |
| 25 to below 30 | Overweight / pre-obese | Obesity grade 1 |
| 30 to below 35 | Obesity class I | Obesity grade 2 |
| 35 to below 40 | Obesity class II | Severe obesity (grade 3) |
| 40 or above | Obesity class III | Severe obesity (grade 4) |
WHO defines overweight from BMI 25 and obesity from 30. JASSO classifies obesity from 25. A BMI of 25 or above alone does not establish a diagnosis of obesity disease.
Scope and limitations
This provides a broad reference for adult body size. Age is not entered: confirm that adult criteria apply. Use caution for children and adolescents, pregnancy and postpartum, substantial oedema or ascites, amputations and other circumstances in which usual height/weight measures are not applicable. BMI alone does not diagnose obesity disease or nutritional status. This tool does not determine treatment or whether weight loss is needed.
Methods and sources
WHO adult classification (WHO 2000 categories, checked against WHO Europe information; its table refers to adults over 20). JASSO 2022 Table 1-3 applies to adults in Japan. Original reference check: 2026-11-10.