Free Online BMI Calculator
Calculate your Body Mass Index (BMI) using either metric or imperial measurements. See where you fall on the BMI scale with visual indicators and get personalized health guidance.
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Understanding Body Mass Index
How BMI Is Calculated
Body Mass Index (BMI) is calculated by dividing your weight in kilograms by your height in meters squared: BMI = kg/m². For imperial units, the formula is (weight in pounds × 703) ÷ (height in inches²). A BMI of 18.5–24.9 is considered normal weight, under 18.5 is underweight, 25–29.9 is overweight, and 30+ is obese. While BMI is a useful screening tool, it doesn't distinguish between muscle and fat mass.
Limitations of BMI
BMI doesn't tell the whole story. Athletes with high muscle mass may have a "overweight" BMI despite being very fit. Conversely, an older adult with low muscle mass might have a "normal" BMI but carry excess body fat. Waist circumference, body fat percentage, and waist-to-hip ratio are complementary measures that provide a more complete picture of health. Always consult a healthcare professional for personalized assessments.