Adult BMI Calculator
Estimate adult BMI using metric or US units, see your category, and compare against a typical 'healthy' range. Educational only, not medical advice.
This calculator is for educational purposes only and does not provide medical advice, diagnosis, or treatment recommendations.
Enter Your Information
For adults 18 years and older only
Enter your height and weight to calculate your BMI.
Understanding BMI (Body Mass Index)
BMI (Body Mass Index) is a simple calculation that uses your height and weight to estimate body fat. It's calculated by dividing your weight in kilograms by the square of your height in meters (BMI = kg/m²). For US units, the formula converts pounds and inches to metric equivalents.
How BMI is Used
BMI is commonly used as a screening tool to categorize weight status. It provides a quick, standardized way to assess whether someone's weight might be associated with health risks. Healthcare providers often use BMI as one of several factors when evaluating overall health.
BMI Categories
- Underweight: BMI below 18.5
- Normal weight: BMI 18.5 to 24.9
- Overweight: BMI 25.0 to 29.9
- Obesity Class 1: BMI 30.0 to 34.9
- Obesity Class 2: BMI 35.0 to 39.9
- Obesity Class 3: BMI 40.0 and above
Important Limitations
BMI does not directly measure body fat and has significant limitations:
- It doesn't distinguish between muscle and fat—very muscular people may have a high BMI despite low body fat
- It doesn't account for bone density, body composition, or fat distribution
- It may not be accurate for older adults, who tend to lose muscle mass
- It doesn't account for pregnancy, which affects weight and body composition
- It may not be appropriate for certain ethnic groups or body types
Important: This calculator is for educational purposes only and does not provide medical advice, diagnosis, or treatment recommendations. BMI is just one indicator and should not be used alone to assess health. Always consult with a healthcare professional for personalized health assessment and guidance.
Frequently Asked Questions
Common questions about BMI, body mass index, and how this calculator works.
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