Body Mass Index (BMI) Calculator
Check your health status with our accurate chart for adults and kids.
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Enter your weight and height to calculate your BMI
BMI Categories
Evidence-Based Information
Based on scientific research and guidelines from leading health organizations
About BMI (Body Mass Index)
Body Mass Index (BMI) is a person's weight in kilograms divided by the square of height in meters. BMI is an inexpensive and easy screening method for weight category—underweight, healthy weight, overweight, and obesity.
BMI does not measure body fat directly, but BMI is moderately correlated with more direct measures of body fat. Furthermore, BMI appears to be as strongly correlated with various metabolic and disease outcomes as are these more direct measures of body fatness.
Limitations of BMI
- May overestimate body fat in athletes and others with muscular builds
- May underestimate body fat in older persons and others who have lost muscle mass
- Does not account for factors like age, sex, ethnicity, and muscle mass
Body Mass Index (BMI) Detailed Guide
BMI Classification Categories
| Classification | BMI Range (kg/m²) | Health Status |
|---|---|---|
| Severe Underweight | < 16.0 | Requires medical attention |
| Moderate Underweight | 16.0 - 16.9 | Health consultation recommended |
| Mild Underweight | 17.0 - 18.4 | Monitor and improve nutrition |
| Normal Weight | 18.5 - 24.9 | Healthy range |
| Overweight | 25.0 - 29.9 | Lifestyle adjustments suggested |
| Obesity Class I | 30.0 - 34.9 | Medical advice recommended |
| Obesity Class II | 35.0 - 39.9 | Professional guidance needed |
| Obesity Class III | ≥ 40.0 | Immediate medical consultation |
Understanding Low BMI (Underweight Conditions)
A Body Mass Index below 18.5 kg/m² indicates underweight status. This condition can result from various factors including inadequate nutrition, metabolic issues, or underlying health conditions.
Potential Health Considerations
- • Nutritional deficiencies affecting overall health
- • Reduced immune system function and increased infection risk
- • Bone density concerns and osteoporosis risk
- • Fatigue and decreased energy levels
- • Reproductive health considerations
Recommended Approaches
- • Consult with healthcare providers for comprehensive assessment
- • Develop balanced nutrition plan with adequate caloric intake
- • Incorporate strength training to build healthy muscle mass
- • Address any underlying medical conditions
- • Regular monitoring of weight and overall health status
Understanding High BMI (Overweight and Obesity)
A Body Mass Index of 25 kg/m² or higher indicates overweight status, while 30 kg/m² or higher indicates obesity. These conditions can impact multiple aspects of health and wellbeing.
Health Considerations
- • Cardiovascular system strain and hypertension risk
- • Metabolic conditions including type 2 diabetes
- • Joint stress and musculoskeletal concerns
- • Respiratory function and sleep quality impacts
- • Overall mobility and physical function considerations
Management Strategies
- • Seek professional medical guidance for personalized plans
- • Implement gradual, sustainable lifestyle modifications
- • Combine balanced nutrition with regular physical activity
- • Focus on long-term health improvements rather than rapid changes
- • Regular health monitoring and professional follow-up
BMI Formula: How to Calculate BMI?
The Body Mass Index calculation depends on the measurement system you are using. Here are the formulas for both Metric and Imperial systems:
Metric System (kg & meters)
BMI = weight (kg) / [height (m)]²
Example: Weight = 68 kg, Height = 1.65 m
Calculation: 68 ÷ (1.65)² = 24.98
Imperial System (lbs & inches)
BMI = 703 × weight (lbs) / [height (in)]²
Example: Weight = 150 lbs, Height = 5'5" (65")
Calculation: 703 × 150 ÷ (65)² = 24.96
General Health Recommendations
For All BMI Categories
Regular health check-ups and professional medical consultations are essential regardless of BMI category. Individual health circumstances vary, and personalized guidance from healthcare providers ensures appropriate health management strategies.
Lifestyle Considerations
Balanced nutrition, regular physical activity, adequate sleep, and stress management contribute to overall health beyond BMI measurements. These factors work together to support long-term wellbeing and disease prevention.
Monitoring and Adjustment
Regular health parameter monitoring allows for timely adjustments to lifestyle approaches. Progress should be measured through multiple health indicators rather than BMI alone, providing a comprehensive view of health status.
Frequently Asked Questions (FAQ)
What is a healthy BMI range?
A healthy BMI range for adults is typically between 18.5 and 24.9 kg/m². However, individual factors like age, muscle mass, and ethnicity can influence what constitutes a healthy weight.
Why is BMI not always accurate?
BMI doesn't distinguish between fat and muscle mass, so it may overestimate body fat in athletes and underestimate it in older adults who have lost muscle mass.
How often should I check my BMI?
For most adults, checking BMI every 3-6 months is sufficient unless you are actively working on weight management.
Sources and References
The information and calculations on this page are based on established guidelines and research from leading health organizations. We are committed to providing accurate and transparent information.
- Centers for Disease Control and Prevention (CDC) - "About Adult BMI"
- World Health Organization (WHO) - "Obesity and Overweight Fact Sheet"
- National Heart, Lung, and Blood Institute (NHLBI) - "BMI Calculator"
- Mayo Clinic - "BMI Calculator: What your BMI result means"
Medical Disclaimer
This BMI Calculator is an educational tool designed to provide general information and should not be considered medical advice. The results are based on standard guidelines and may not account for individual health circumstances, genetic factors, or concurrent medical conditions. Always consult with a qualified healthcare professional for proper interpretation of your results, personalized target goals, and treatment recommendations. Do not make changes to medications or treatment plans without consulting your physician.
Important Health Information
This information is provided for educational purposes only. Body Mass Index is a screening tool that should be used as part of comprehensive health assessment by qualified healthcare professionals.
Individual health circumstances vary significantly. Always consult with healthcare providers for medical advice, diagnosis, and treatment recommendations tailored to your specific health needs.
Calculate BMI by Age and Gender
Explore specific BMI analysis and health insights tailored for different demographic groups. Understanding how weight health varies by age and gender is key to long-term wellness.