Calculate your Body Mass Index from height and weight — with BMI category, healthy weight range, BMI bar and personalised insights.
Enter your figures and click Calculate to see your results.
Enter your weight and height — use cm directly or enter feet and inches and the calculator will convert automatically.
Press the Calculate button. Results appear instantly using standard clinical and scientific formulas.
Results are displayed with all key values clearly labelled. Use the Copy button to grab your results or Download to save a text file. For health decisions, always consult a healthcare professional.
BMI (Body Mass Index) is calculated as weight (kg) divided by height (m) squared: BMI = kg/m². In imperial units: BMI = (lbs × 703) / inches². It is a simple screening tool for weight status but does not directly measure body fat.
WHO BMI categories: Underweight = below 18.5, Normal weight = 18.5–24.9, Overweight = 25.0–29.9, Obese Class I = 30.0–34.9, Obese Class II = 35.0–39.9, Obese Class III (Severe) = 40+. Asian populations often use slightly lower thresholds.
BMI is unreliable for athletes and people with high muscle mass, as muscle weighs more than fat. A muscular person may have a high BMI yet very low body fat percentage. BMI should be used alongside waist circumference, body fat percentage and other health markers for a complete picture.
For most adults, a BMI of 18.5–24.9 is considered healthy. However, health is more than BMI alone — blood pressure, blood sugar, cholesterol, activity level and diet all contribute to overall health and disease risk, regardless of BMI category.
Children use age- and sex-specific BMI percentile charts rather than fixed adult categories. Underweight = below 5th percentile; Healthy = 5th–84th percentile; Overweight = 85th–94th percentile; Obese = 95th percentile or above, all compared to children of the same age and sex.
