Lunia · Free tools
BMI Calculator
Calculate adult BMI and understand the screening category.
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How this calculator works
Body mass index equals weight in kilograms divided by height in metres squared. Adult CDC screening categories are below 18.5, 18.5 to below 25, 25 to below 30, and 30 or more. Classification uses the unrounded value.
A worked example
Body weight: 70 · Weight unit: Kilograms · Height: 170 · Length unit: Centimetres
- BMI
- 24.2 kg/m²
- Adult screening category
- Healthy weight
These are illustrative inputs, not personal recommendations.
Common questions
Can BMI tell muscle from fat?
No. Two people with the same BMI can have very different muscle mass and body composition. A wider clinical assessment provides context.
How should I use the result?
For adults aged 20 and over. BMI is a screening measure, not a diagnosis, body-fat percentage or assessment of individual health. It is not appropriate for evaluating pregnancy or children.
Sources & method references
Formula-based results are estimates, not individual medical advice.