Adult BMI calculator
Calculate an adult’s body mass index from height and weight, with general reference categories and clear limitations.
BMI is not a diagnosis and does not distinguish muscle from fat. These general thresholds are not personalised for age, ethnic background or body composition. Do not use this tool for children, during pregnancy, or with a diagnosed or suspected eating disorder. Ask a healthcare professional if you have concerns.
Calculations run only in this page’s memory. This tool does not send or save your entries or results.
Enter height in centimetres and weight in kilograms. For adults aged 18 and over only.
How it works
How it works
BMI = weight in kg ÷ (height in cm ÷ 100)². General categories: below 18.5; from 18.5 to below 25; from 25 to below 30; 30 or above. The category uses the unrounded result.
- < 18.5 kg/m²: Underweight
- 18.5 ≤ x < 25 kg/m²: Reference range
- 25 ≤ x < 30 kg/m²: Overweight
- ≥ 30 kg/m²: Obesity category
Example
At 70 kg and 170 cm, BMI is approximately 24.2, within the general reference range.
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