Your BMI Results
Enter your measurements and calculate to see your BMI, weight category, and health guidance.
BMI Classification Chart
World Health Organization (WHO) Standards
Severe Underweight
BMI < 16.0
Moderate Underweight
BMI 16.0 - 16.9
Mild Underweight
BMI 17.0 - 18.4
Normal Weight
BMI 18.5 - 24.9
Overweight (Pre-Obese)
BMI 25.0 - 29.9
Obese Class I
BMI 30.0 - 34.9
Obese Class II
BMI 35.0 - 39.9
Obese Class III (Severe)
BMI ≥ 40.0
How to Use the BMI Calculator
Professional Body Mass Index calculator for accurate weight assessment. Calculate BMI using imperial or metric measurements with instant health category classification.
Step-by-Step Instructions
- Select Unit System: Choose Imperial (pounds/inches) or Metric (kilograms/centimeters).
- Enter Weight: Input your current weight. For adults, typical ranges are 100-300 lbs or 45-135 kg.
- Enter Height: For imperial, enter feet and inches separately. For metric, enter total height in centimeters.
- Calculate: View your BMI value, weight category, and personalized health guidance.
Uses standard BMI formulas: Imperial: BMI = (weight_lbs / height_in²) × 703 and Metric: BMI = weight_kg / (height_m)². Same calculations used by healthcare professionals worldwide.
Understanding Your Results
- Underweight (BMI < 18.5): May indicate nutritional deficiency or health concerns. Consider consulting healthcare provider.
- Normal Weight (BMI 18.5-24.9): Optimal range for most adults. Maintain through balanced diet and regular exercise.
- Overweight (BMI 25-29.9): Increased health risk. Consider lifestyle modifications with professional guidance.
- Obese (BMI ≥ 30): Significant health risk. Consult healthcare provider for personalized weight management plan.
BMI Limitations
BMI is a screening tool, not diagnostic. It doesn't distinguish between muscle and fat mass. Athletes, bodybuilders, pregnant women, and elderly may get inaccurate results. Consult healthcare professionals for comprehensive health assessment including waist circumference, body composition, and overall health factors.
Frequently Asked Questions
How accurate is BMI as a health indicator?
BMI is a useful screening tool but has limitations. It doesn't distinguish between muscle and fat mass, so athletes or very muscular individuals may register as overweight despite being healthy. Similarly, older adults may have normal BMI despite excess body fat. Use BMI as one of several health indicators alongside waist circumference, body composition, and overall health assessment by healthcare professionals.
What is considered a healthy BMI?
For most adults, a BMI between 18.5 and 24.9 is considered healthy. Under 18.5 is underweight, 25-29.9 is overweight, and 30 or above is obese. However, healthy ranges may vary based on age, sex, ethnicity, muscle mass, and individual health factors. Always consult healthcare providers for personalized health assessment.
Should children use this BMI calculator?
No, this calculator is designed for adults 20 years and older. Children and teens require age and sex-specific BMI percentiles for accurate assessment, as their body composition changes during growth. Pediatric BMI charts account for developmental stages. Consult a pediatrician for appropriate BMI evaluation for children and adolescents under 20.
What should I do if my BMI is outside the healthy range?
If your BMI suggests you're underweight or overweight, consult with a healthcare provider or registered dietitian. They can assess your overall health, discuss potential risks, and create a personalized plan for achieving healthy weight through balanced nutrition, regular physical activity, and lifestyle modifications. Avoid extreme diets or rapid weight changes without professional guidance.
Does BMI work for bodybuilders and athletes?
BMI has significant limitations for athletes and bodybuilders. Muscle weighs more than fat, so highly muscular individuals often have elevated BMI despite low body fat percentage. For athletes, body composition analysis (body fat percentage, lean muscle mass) provides more accurate health assessment than BMI alone. Consider additional measurements like waist-to-hip ratio and professional body composition testing.
How often should I calculate my BMI?
For general health monitoring, calculating BMI every 3-6 months is sufficient unless you're actively trying to lose or gain weight. If you're on a weight management program, monthly calculations can help track progress. Remember that weight naturally fluctuates day-to-day, so focus on long-term trends rather than daily changes. Combine BMI tracking with other health metrics for comprehensive wellness monitoring.