Looking for more details? Read our comprehensive BMI guide
What is BMI?
Body mass index (BMI) is a simple index of weight-for-height that is commonly used to classify underweight, overweight and obesity in adults. It is defined as a person's weight in kilograms divided by the square of their height in meters (kg/m²).
Standard Reference Ranges
- Underweight < 18.5
- Normal weight 18.5 – 24.9
- Overweight 25.0 – 29.9
- Obese ≥ 30.0
Clinical Significance
For most people, BMI is a reliable indicator of body fatness. It is used as a screening tool to identify possible weight problems for adults. However, BMI is not a diagnostic tool. To determine if excessive weight is a health risk, a healthcare provider would need to perform further assessments.
Case Scenario
Patient: A 45-year-old male presents for a routine check-up. He weighs 95 kg and is 175 cm tall.
Calculation: BMI = 95 / (1.75)² = 31.0 kg/m²
Interpretation: His BMI is 31.0, which falls into the obese category (Class I Obesity).
Next Steps: Advise the patient on weight management, screen for metabolic syndrome, and recommend lifestyle modifications including diet and exercise.
Frequently Asked Questions
BMI does not distinguish between muscle mass and body fat. Athletes with high muscle mass may have a high BMI without having excess body fat.
Yes, certain populations (like South Asians) may face health risks at a lower BMI. The WHO suggests public health action points at 23.0 and 27.5 for Asian populations.
References
- World Health Organization (WHO). Obesity and overweight. 2021.
- Centers for Disease Control and Prevention (CDC). About Adult BMI.
How to Use
Enter the individual's height and weight. You can choose metric or imperial units. The tool calculates the Body Mass Index and provides the standard WHO classification.