BMI Calculator — Body Mass Index
Calculate your Body Mass Index to check if your weight is in a healthy range.
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What Is BMI and How Is It Calculated?
Body Mass Index (BMI) is a screening tool that estimates body fat based on your height and weight. The formula is: BMI = weight (kg) ÷ height (m)². In US units: BMI = (weight in pounds × 703) ÷ (height in inches)². While not a direct measure of body fat, BMI serves as a quick initial assessment used by healthcare providers worldwide.
BMI Categories (Adults 20+)
| BMI Range | Category | Health Risk |
|---|---|---|
| Below 18.5 | Underweight | Nutritional deficiency risk |
| 18.5 – 24.9 | Normal weight | Lowest overall risk |
| 25.0 – 29.9 | Overweight | Moderately increased risk |
| 30.0 – 34.9 | Obese (Class I) | High risk |
| 35.0 – 39.9 | Obese (Class II) | Very high risk |
| 40.0+ | Obese (Class III) | Extremely high risk |
Limitations of BMI
BMI has well-known limitations. It does not distinguish between muscle and fat, so athletes and bodybuilders may have a "high" BMI despite being very fit. It also doesn't account for fat distribution — visceral fat (around organs) is more dangerous than subcutaneous fat (under skin). For a more complete picture, healthcare providers often combine BMI with waist circumference, body fat percentage, and metabolic health markers.
BMI for Children and Teens
For individuals under 20, BMI is interpreted differently using age- and sex-specific percentile charts from the CDC. A child in the 85th–94th percentile is classified as overweight, while the 95th percentile or above indicates obesity. This calculator is designed for adults; consult your pediatrician for children's BMI assessment.
Healthy Weight Range
For a 5'10" person, the healthy BMI range (18.5–24.9) corresponds to roughly 129–174 pounds. For a 5'4" person, it's approximately 108–145 pounds. These ranges provide a general guideline — your ideal weight depends on many individual factors including age, muscle mass, bone density, and overall health.
Frequently Asked Questions
A healthy BMI for adults is between 18.5 and 24.9. This range is associated with the lowest health risks from weight-related conditions.
BMI is a useful screening tool but has limitations. It doesn't distinguish between muscle and fat mass, so athletic individuals may show a higher BMI despite being healthy.