BMI Calculator
Calculate your Body Mass Index (BMI) to understand whether your weight is in a healthy range for your height. Supports both metric and imperial units.
BMI Calculator
Body Mass Index
BMI Categories
| BMI Range | Category | Health Risk |
|---|---|---|
| < 18.5 | Underweight | Moderate |
| 18.5 – 24.9 | Normal Weight | Minimal |
| 25.0 – 29.9 | Overweight | Increased |
| 30.0 – 34.9 | Obese Class I | High |
| 35.0 – 39.9 | Obese Class II | Very High |
| ≥ 40.0 | Obese Class III | Extremely High |
How BMI Is Calculated
BMI is calculated by dividing your weight by your height squared.
BMI = Weight (kg) ÷ Height² (m)
Imperial: BMI = (Weight (lbs) × 703) ÷ Height² (inches)
Example: A person weighing 75 kg who is 1.75 m tall has a BMI of 75 / (1.75)² = 24.5 — which falls in the Normal Weight range.
BMI does not account for muscle mass, bone density, age, or ethnicity. Athletes may have a high BMI without being unhealthy. Always consult a healthcare professional for a comprehensive health assessment.
Frequently Asked Questions
BMI is a useful general screening tool, but it has limitations. It can overestimate fat in muscular individuals (like athletes) and underestimate it in older adults who've lost muscle mass. It's also less accurate for children, pregnant women, and certain ethnicities.
According to the World Health Organization (WHO), a healthy BMI for adults is between 18.5 and 24.9. However, optimal ranges may differ slightly by age, sex, and ethnicity.
This calculator is designed for adults aged 18–65. For children and teenagers, BMI is interpreted differently using age- and sex-specific growth charts. Consult a pediatrician for children's weight assessments.