Adult BMI Calculator

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.