When to use this calculator
Calculate adult body mass index from height and weight. For adults aged 20 or older. BMI is a screening measure, not a diagnosis or a measure of body composition.
Explore the adult body measurements calculators for other questions in this topic. For a related calculation, use the Body Fat Percentage Calculator: Estimate adult body fat percentage using the BMI-based Deurenberg equation, age and sex coefficient.
BMI describes one relationship, not overall health
Two adults with identical height and weight receive the same BMI even if their muscle mass and body composition differ. Pregnancy, fluid changes and other circumstances can further limit interpretation. This page reports the number without diagnosing a condition or setting a weight target.
PUTTING IT INTO PRACTICE
BMI: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Age in years (integer) | 30 |
| Weight (kg) | 70 |
| Height (cm) | 175 |
| Result | 22.857143 kg/m² |
- Check the input labels and enter the example values above.
- Apply the relationship: BMI = weight(kg)/(height(m)²)..
- The result is 22.857143 kg/m², rounded for display.
How to interpret your result
For adults aged 20 or older. BMI is a screening measure, not a diagnosis or a measure of body composition.
These tools are for adults aged at least twenty. BMI relates body mass to squared height and does not directly measure body fat, fitness, nutrition or individual health. It is an informational screening measure rather than a diagnosis.
Frequently asked questions
Can children use this adult calculator?
No. The calculator is restricted to ages 20 and older. Interpreting BMI in children and adolescents uses age- and sex-specific growth references rather than this adult-only approach.
Can BMI measure body composition?
No. BMI uses only mass and height. It does not distinguish muscle, fat, bone or fluid and cannot replace an individual health assessment.
When is the bmi calculator useful?
Calculate adult body mass index from height and weight. For adults aged 20 or older. BMI is a screening measure, not a diagnosis or a measure of body composition.
How do I use the bmi calculator?
Enter age in years (integer), weight (kg), height (cm). The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
BMI = weight(kg)/(height(m)²)..
What should I check before using the result?
For adults aged 20 or older. BMI is a screening measure, not a diagnosis or a measure of body composition.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
Further reading
For background on this topic, see CDC: adult BMI ↗. This is a topic reference, not an external review or endorsement of this tool.
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