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BMI Calculator — Tips & Guide
Body Mass Index (BMI) is a quick screening tool based on height and weight. Use it as a starting point, not a definitive health assessment.
BMI Limitations
BMI doesn't distinguish between muscle and fat. Athletes with high muscle mass may show an "overweight" BMI despite being in excellent health. Consider body fat percentage for a fuller picture.
Check BMI Regularly
Track BMI over time rather than focusing on a single reading. A gradual trend is more meaningful than any one data point. Recheck every 3–6 months.
BMI vs Body Fat %
Body fat percentage is a more precise health measure. BMI is calculated from weight and height alone, while body fat % distinguishes fat from lean mass. Use both together for best insight.
A BMI between 18.5 and 24.9 is considered the "Normal weight" range for most adults. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above falls into the obese category. These thresholds are the same for men and women.
BMI is a useful population-level screening tool but has limitations for individuals. It doesn't account for muscle mass, bone density, age, sex, or fat distribution. A muscular person may be classified as overweight, while a sedentary person with low muscle mass may show a "normal" BMI despite having excess body fat.
BMI = weight in kilograms divided by height in meters squared. For example, a person weighing 70 kg at 175 cm has a BMI of 70 ÷ (1.75 × 1.75) = 22.9. In imperial units, the formula is BMI = (weight in lbs × 703) ÷ (height in inches)².
A BMI of 30.0 or higher is classified as obese. The obese category is further divided: Class I (30.0–34.9), Class II (35.0–39.9), and Class III — sometimes called severe or morbid obesity — is 40.0 and above. These classifications help guide medical treatment recommendations.