BMI Calculator
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About BMI and Body Mass Index
Body Mass Index is a screening measure that relates weight to height. This calculator accepts metric or imperial measurements, converts them consistently, and displays an adult BMI category alongside the number. It is useful for a quick population-level reference, but it does not directly measure body fat, muscle, bone, waist circumference, fitness, or metabolic health.
Interpret BMI alongside the wider picture, including body composition, waist measurements, strength, blood pressure, lab results, age, and personal history. Athletes and people with higher lean mass may receive a higher category without the same health implications, while a normal BMI does not rule out health risks. Children, pregnancy, and some ethnic populations require context-specific guidance rather than a simple adult cutoff.
Frequently Asked Questions
What does BMI measure?
BMI is a weight-for-height screening index calculated from weight divided by height squared. It can describe broad population patterns, but it is not a direct measurement of body fat or overall health.
What is the usual adult healthy BMI range?
For many adult screening guidelines, 18.5 to 24.9 is labeled the healthy range. Cutoffs are not a diagnosis and should be interpreted with age, body composition, waist size, and other health information.
Why might BMI be misleading for athletes?
BMI cannot distinguish muscle from fat. A muscular person may weigh more for their height and fall into a higher category even when their body-fat level and fitness are favorable.
Can I use adult BMI categories for children?
No. Children and adolescents are generally assessed with BMI-for-age percentiles that account for growth and sex. Use pediatric guidance for a child rather than interpreting this adult calculator alone.