Calculate your Body Mass Index instantly. Supports metric and imperial units with category labels and visual gauge.
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Knowledge Base
BMI = weight (kg) / height² (m²) for metric units. For imperial, BMI = (weight in lbs / height in inches²) × 703. For example, a person 170 cm tall weighing 70 kg has a BMI of 70 / 1.7² = 24.2.
Under 18.5 = Underweight; 18.5–24.9 = Normal weight; 25.0–29.9 = Overweight; 30.0 and above = Obese. These thresholds are defined by the World Health Organization (WHO).
BMI is a simple screening tool, not a diagnostic measure. It does not account for muscle mass, bone density, body fat distribution, or age. Athletes often have high BMI despite low body fat. Consult a healthcare professional for a full assessment.
For adults, a BMI between 18.5 and 24.9 is generally considered healthy. However, optimal ranges can vary by age, sex, and ethnicity. Asian populations may face health risks at lower BMI thresholds.