BMI Calculator & Body Mass Index Health Guide
Body Mass Index (BMI) is a standardized screening metric used by physicians, healthcare professionals, and fitness experts worldwide to evaluate whether an individual's weight falls within a healthy range relative to their height. Use our free, private BMI Calculator to determine your BMI score and weight category instantly.
The Mathematical BMI Formula
BMI is calculated by dividing an individual's weight in kilograms by the square of their height in meters:
- Metric Formula:
BMI = weight (kg) / [height (m)]² - Imperial Formula:
BMI = [weight (lbs) / [height (inches)]²] × 703
Standard World Health Organization (WHO) Weight Categories
- Underweight: BMI less than 18.5
- Normal / Healthy Weight: BMI between 18.5 and 24.9
- Overweight: BMI between 25.0 and 29.9
- Obesity (Class 1): BMI between 30.0 and 34.9
- Obesity (Class 2): BMI between 35.0 and 39.9
- Severe / Morbid Obesity (Class 3): BMI of 40.0 or higher
Understanding BMI Limitations
While BMI is an excellent broad screening metric for populations, it does not directly measure body fat percentage, bone density, or muscle mass. For bodybuilders and athletes with high muscle density, BMI may classify them as overweight even with low body fat. Always consult healthcare professionals for comprehensive body composition assessments.
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