BMI Calculator
Calculate your Body Mass Index (BMI) and see which weight category it falls into.
Your BMI
Category
Adult BMI categories only apply from age 20. For children and teens, BMI is assessed using age- and sex-specific growth charts — ask a pediatrician or GP rather than relying on the category above.
This calculator provides a general estimate for informational purposes only. It is not a medical device and does not provide medical advice or diagnosis. Always consult a qualified healthcare professional about your individual health circumstances.
Frequently Asked Questions
What is BMI?
Body Mass Index (BMI) is a measure based on your height and weight. It's a general screening tool, not a diagnostic measure of body composition or health.
What are the BMI categories?
Underweight is below 18.5, normal weight is 18.5–24.9, overweight is 25–29.9, and obese is 30 or above. These World Health Organization / CDC thresholds are the same for men and women — but only apply from age 20 onward. Under 20, BMI is assessed against age- and sex-specific growth charts instead.
Is BMI accurate for everyone?
BMI doesn't distinguish muscle from fat, so it can misclassify very muscular people as overweight, and can understate body fat in older adults as muscle mass naturally declines. During pregnancy, weight-related guidance is based on your pre-pregnancy BMI, not your current weight. The World Health Organization also recommends lower BMI cut-offs for some Asian populations (overweight from 23, obese from 27.5), reflecting higher health risk at a given BMI in those groups. It's a general screening guide, not a diagnosis.
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