📏 BMI Calculator
Check your Body Mass Index based on the WHO scale
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Check your Body Mass Index based on the WHO scale
Body Mass Index (BMI) is a numerical value calculated from your weight and height. The formula divides your weight in kilograms by your height in meters squared (kg/m²). Developed by Belgian mathematician Adolphe Quetelet in the 1830s, BMI has become the most widely used screening tool for categorizing weight status in adults. The World Health Organization (WHO) uses BMI as the standard classification system for underweight, normal weight, overweight, and obesity worldwide.
The WHO defines four primary BMI categories: Underweight (below 18.5), Normal weight (18.5 to 24.9), Overweight (25.0 to 29.9), and Obese (30.0 and above). Obesity is further divided into Class I (30-34.9), Class II (35-39.9), and Class III or severe obesity (40+). These thresholds were established through large population studies linking BMI ranges to health outcomes including cardiovascular disease, diabetes, and mortality risk.
While BMI is a useful screening tool, it has well-documented limitations. It does not distinguish between muscle mass and fat mass, meaning athletes with high muscle mass may be classified as overweight despite having low body fat. BMI also does not account for bone density, age, sex, ethnicity, or fat distribution. Visceral fat (around organs) is more dangerous than subcutaneous fat, but BMI cannot differentiate between them. For a complete health assessment, consult a healthcare professional who can consider additional measurements like waist circumference, body fat percentage, and blood markers.
Maintaining a healthy weight involves a combination of balanced nutrition, regular physical activity, adequate sleep, and stress management. The Centers for Disease Control (CDC) recommends at least 150 minutes of moderate-intensity aerobic activity per week for adults. A sustainable approach focuses on gradual lifestyle changes rather than extreme dieting, which often leads to weight cycling. If your BMI falls outside the normal range, speak with your doctor about a personalized plan that accounts for your overall health profile.
Research suggests that BMI thresholds may need adjustment for different ethnic groups. For example, Asian populations tend to have higher body fat percentages at lower BMI values, leading some health organizations to recommend lower cutoff points (23 instead of 25 for overweight). Conversely, some Pacific Islander and African populations may have lower body fat at the same BMI. Our calculator uses the standard WHO thresholds, but these population-specific considerations are worth discussing with your healthcare provider.
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