Calculate your Body Mass Index
The Body Mass Index (BMI) is a globally recognized metric for assessing body weight relative to height. It was developed in the 19th century by Belgian statistician Adolphe Quetelet and is now used by the World Health Organization (WHO), doctors, and nutritionists as a rough guideline for categorizing underweight, normal weight, and overweight.
BMI provides a quick indication of whether your weight is in a healthy range. However, it does not replace a medical examination and should be considered as just one of several indicators of your health.
The calculator instantly determines your BMI value and assigns it to the appropriate weight category.
BMI = Body Weight (kg) / Height (m)²
Example: At 80 kg and 1.80 m: 80 / (1.80 × 1.80) = 80 / 3.24 = 24.7
Severe Underweight: BMI below 16.0
Moderate Underweight: BMI 16.0 – 16.9
Mild Underweight: BMI 17.0 – 18.4
Normal Weight: BMI 18.5 – 24.9
Pre-obesity (Overweight): BMI 25.0 – 29.9
Obesity Class I: BMI 30.0 – 34.9
Obesity Class II: BMI 35.0 – 39.9
Obesity Class III: BMI 40.0 or higher
BMI has limitations: Athletes with high muscle mass may have an elevated BMI even though they are healthy and fit (muscle is heavier than fat). Elderly people lose muscle mass, which can skew BMI. For children and teenagers, age and gender-specific percentile tables apply.
Complementary measurements include: waist circumference, waist-to-hip ratio (WHR), body fat percentage (via calipers or bioimpedance), FFMI (fat-free mass index) for athletes, and waist-to-height ratio (WHtR).
Belly fat (visceral fat) is considered particularly harmful to health and is associated with increased risk of cardiovascular disease and diabetes. For men, waist circumference should be below 40 inches (102 cm), for women below 35 inches (88 cm).
For overweight: balanced diet with calorie deficit, regular exercise (at least 150 min/week), adequate sleep, stress reduction. For underweight: calorie-rich, nutrient-dense foods, possibly strength training for muscle building. When in doubt, always seek medical advice.
Note: The BMI calculator is for guidance only and does not replace medical advice. For questions about your weight or health, please consult a doctor or nutritionist.
The Body Mass Index is a simple calculation using a person's height and weight. The formula is BMI = kg/m².