BMI Calculator: Check Your Body Mass Index
A person who is 5'10" and weighs 175 lbs has a BMI of 25.1, which falls in the "Overweight" category per WHO standards. A healthy BMI range is 18.5-24.9. BMI is calculated as weight (kg) divided by height (m) squared.
Calculate Your BMI
Enter your height and weight.
Your BMI
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BMI Categories (WHO Classification)
| BMI Range | Category | Health Risk |
|---|---|---|
| Below 18.5 | Underweight | Increased risk of nutritional deficiency |
| 18.5 - 24.9 | Normal weight | Lowest health risk |
| 25.0 - 29.9 | Overweight | Increased risk of cardiovascular disease |
| 30.0 - 34.9 | Obesity Class I | High risk |
| 35.0 - 39.9 | Obesity Class II | Very high risk |
| 40.0+ | Obesity Class III | Extremely high risk |
How BMI Is Calculated
Metric: BMI = weight (kg) / height (m)^2 Imperial: BMI = (weight (lbs) x 703) / height (inches)^2
For example, a 170 lb person who is 5'9" (69 inches): BMI = (170 x 703) / (69 x 69) = 119,510 / 4,761 = 25.1
Limitations of BMI
BMI does not account for muscle mass, bone density, age, sex, or fat distribution. Athletes and individuals with high muscle mass may have an elevated BMI without excess body fat. Conversely, older adults who have lost muscle may have a normal BMI despite carrying excess fat. For a more complete picture, consider measuring your waist circumference, waist-to-hip ratio, or body fat percentage alongside BMI.
1. World Health Organization. Body mass index - BMI. WHO Regional Office for Europe. https://www.who.int/europe/news-room/fact-sheets/item/a-healthy-lifestyle---who-recommendations
2. CDC. About Adult BMI. Centers for Disease Control and Prevention. https://www.cdc.gov/healthyweight/assessing/bmi/adult_bmi/
3. Flegal KM, Kit BK, Orpana H, Graubard BI. Association of all-cause mortality with overweight and obesity using standard body mass index categories. JAMA. 2013;309(1):71-82. doi:10.1001/jama.2012.113905
Frequently Asked Questions
What is a healthy BMI?
A healthy BMI for adults is between 18.5 and 24.9 according to the World Health Organization. This range is associated with the lowest risk of weight-related health conditions including type 2 diabetes, cardiovascular disease, and certain cancers.
Is BMI accurate for athletes?
BMI can overestimate body fatness in athletes and people with high muscle mass. Muscle is denser than fat, so a muscular person may have a high BMI despite having low body fat. If you are athletic, consider using a body fat percentage calculator or DEXA scan for a more accurate assessment.
Does BMI differ by age?
Standard adult BMI categories apply to ages 20 and older. For children and teens (ages 2-19), BMI is interpreted using age- and sex-specific percentiles because body composition changes significantly during growth. This calculator is designed for adults.
Why is BMI still used if it has limitations?
BMI remains the most practical screening tool for weight-related health risk at the population level. It requires only height and weight, is inexpensive, and correlates well with health outcomes in large studies. No single metric is perfect — BMI is best used alongside other measurements like waist circumference and body fat percentage.
What should I do if my BMI is high?
A high BMI suggests you may benefit from lifestyle changes. Consult a healthcare provider for a comprehensive assessment including body fat percentage, blood pressure, cholesterol, and blood sugar. Even modest weight loss (5-10% of body weight) significantly reduces health risks associated with obesity.
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