BMI Calculator

Calculate your Body Mass Index (BMI) to see where you fall on the underweight-to-obese scale. BMI uses your height and weight to estimate body fat.

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How It Works

Body Mass Index (BMI) is a simple screening tool that uses your height and weight to estimate body fat. It was developed by Belgian mathematician Adolphe Quetelet in the 1830s. While BMI does not directly measure body fat, it correlates well enough with more direct measures to serve as a useful first check. A BMI of 18.5 to 24.9 is considered normal weight. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above is obese. Keep in mind that BMI does not distinguish between muscle and fat — a muscular athlete may have a high BMI without excess body fat. For a more complete picture, consider measuring body fat percentage, waist-to-hip ratio, or consulting a healthcare provider.