BMI Calculator
Calculate your Body Mass Index in metric or imperial units. BMI is a useful screening tool but doesn't distinguish between muscle and fat — use it alongside other measurements.
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What do I need to know about The BMI Formula?
BMI = weight (kg) divided by height squared (m). For example, someone weighing 70 kg at 175 cm: height in metres = 1.75, height squared = 3.0625, BMI = 70 ÷ 3.0625 = 22.9. This falls in the healthy weight range. BMI can be calculated from weight in pounds and height in inches using: BMI = (weight in lbs × 703) ÷ height in inches squared. This formula was derived by the Belgian mathematician Adolphe Quetelet in the 1830s and became widely adopted for population health studies in the 1970s.
What do I need to know about BMI Categories?
Under 18.5 is Underweight — associated with increased risk of nutritional deficiencies, bone loss, and immune suppression. 18.5–24.9 is the Healthy Weight range. 25–29.9 is Overweight — associated with moderately elevated risk of cardiovascular disease and type 2 diabetes. 30.0–34.9 is Obese Class I. 35.0–39.9 is Obese Class II. 40 and above is Obese Class III — associated with significantly elevated risk of cardiovascular disease, type 2 diabetes, sleep apnoea, certain cancers, and joint problems.
What should I know about Limitations of BMI?
BMI doesn't distinguish between muscle and fat, and doesn't account for age, sex, or ethnicity. Athletes often score 'overweight' despite being in excellent health. Use it alongside other measurements for a fuller picture.
What should I know about Limitations of BMI?
BMI was created in the 1830s as a population-level statistical measure, not an individual health diagnostic tool. Key limitations: it cannot distinguish between muscle and fat mass (a fit athlete may be classified as obese), it does not account for fat distribution (abdominal fat is more dangerous than the same fat elsewhere), and it is less accurate for older adults and certain ethnic groups. Complementary measures — waist circumference, body fat percentage, and metabolic markers — provide a mo For calorie counts and full nutrition data on thousands of foods, our sister site <a href="https://247caloriecheck.com" rel="noopener">247 Calorie Check</a> covers everything from supermarket staples to restaurant dishes — useful alongside BMI for anyone tracking food intake.