What is BMI?
Body Mass Index (BMI) is a simple, widely used tool to assess whether a person’s weight falls within a healthy range relative to their height. By calculating your BMI, you can quickly identify potential health risks linked to being underweight, overweight, or obese. According to the World Health Organization (WHO), BMI categorizes individuals into standardized ranges, making it a valuable starting point for health evaluations.
BMI Categories
Based on WHO guidelines, BMI ranges are classified as follows:
- Below 16: Severe underweight
- 16–18.5: Underweight
- 18.5–25: Healthy weight
- 25–30: Overweight (pre-obesity)
- 30–35: Obesity class I
- 35–40: Obesity class II
- 40+: Obesity class III (morbid obesity)
Important Limitations
While BMI is a helpful screening tool, it does not distinguish between muscle mass and body fat. Athletes or individuals with high muscle density may register a higher BMI despite being in excellent health. Always pair BMI results with additional health assessments, such as body fat analysis or waist-to-hip ratios, for a comprehensive evaluation.
How to Calculate BMI
The formula for BMI is straightforward:
BMI = Weight (kg) / Height (m)²
For example, a person weighing 70 kg and measuring 1.75 m tall would calculate: 70 / (1.75 × 1.75) = 22.9 (Healthy weight range).
Note: BMI calculations are most accurate for adults aged 20–65. Results may be misleading for children, teens, seniors, or pregnant individuals.
BMI for Children and Teens
Pediatric BMI uses percentiles adjusted for age and gender, reflecting growth patterns unique to youth. Categories include:
- Underweight: Below 5th percentile
- Healthy weight: 5th–85th percentile
- Overweight: 85th–95th percentile
- Obese: 95th percentile or higher
Healthcare providers use these percentiles to monitor development, identify trends, and address potential health risks early. Use our instant BMI calculator now!