BMI Calculator

Body Mass Index (BMI) Information

Introduction

Body Mass Index (BMI) is a simple calculation used to estimate a person's body fat based on their weight and height. It is a widely used screening tool to categorize individuals into weight categories such as underweight, normal weight, overweight, and obese. While BMI does not directly measure body fat, it correlates well with more direct measures of body fat and is a quick and inexpensive method for assessing weight-related health risks.

BMI is used by healthcare professionals to identify potential health risks associated with being underweight, overweight, or obese. However, it is not a diagnostic tool and should be used in conjunction with other assessments (e.g., waist circumference, diet, physical activity, and family history).

BMI Formula

BMI Table for Adults

The following table categorizes BMI ranges for adults (ages 20 and older):

BMI Chart for Adults

| Underweight | Normal Weight | Overweight | Obese       |
|-------------|---------------|------------|-------------|
| < 18.5      | 18.5 – 24.9   | 25.0 – 29.9| ≥ 30.0      |
        

BMI Table for Children and Teens

For children and teens (ages 2–19), BMI is interpreted differently because their body composition varies with age and gender. BMI-for-age percentiles are used to categorize weight status:

BMI Chart for Children and Teens

| Underweight | Healthy Weight | Overweight | Obese       |
|-------------|----------------|------------|-------------|
| < 5th %ile  | 5th – 85th %ile| 85th – 95th| ≥ 95th %ile |
        

Key Notes

• Limitations of BMI:
  • BMI does not distinguish between muscle and fat, so athletes with high muscle mass may have a high BMI but low body fat.
  • It may not accurately reflect body fat in older adults or those with a sedentary lifestyle.
• Health Risks:
  • Underweight: Increased risk of malnutrition, osteoporosis, and weakened immunity.
  • Overweight/Obese: Increased risk of heart disease, diabetes, high blood pressure, and certain cancers.
• Use in Children and Teens:
  • BMI-for-age percentiles account for growth patterns and are more appropriate for assessing weight status in younger populations.