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Learn how BMI works, what your results mean, and how to use this measurement as part of your overall health assessment
Common questions about BMI calculation and interpretation
For adults, a BMI between 18.5 and 24.9 is considered normal weight. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is obese. These ranges apply to most adults but may differ for athletes, older adults, and certain ethnic groups.
BMI is a useful screening tool but does not directly measure body fat. It may overestimate body fat in muscular individuals and underestimate it in older adults who have lost muscle mass. Use BMI alongside other health indicators like waist circumference and body fat percentage.
For metric units: divide weight in kilograms by height in meters squared (kg/m²). For imperial units: multiply weight in pounds by 703, then divide by height in inches squared. Our calculator handles both unit systems automatically.
Yes. BMI for children and teens is interpreted using age- and sex-specific percentile charts rather than fixed adult categories. Use our Kids BMI Calculator for pediatric assessments based on CDC growth standards.
A high BMI may indicate increased health risks, but it is not a diagnosis. Consult a healthcare provider for a full assessment. Lifestyle changes including balanced nutrition, regular physical activity, and adequate sleep can help improve BMI over time.
Standard BMI categories do not apply during pregnancy. Weight gain recommendations during pregnancy depend on your pre-pregnancy BMI. Discuss appropriate weight management with your obstetrician.
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**Medical Disclaimer:** The information provided by this calculator is for educational and informational purposes only and should not be considered as medical advice. Always consult with a qualified healthcare provider before making any decisions about your health or treatment. This tool is not intended to diagnose, treat, cure, or prevent any disease.