Free BMI Calculator - Calculate Body Mass Index
Calculate your Body Mass Index (BMI) instantly and understand your weight status. Used by healthcare professionals worldwide following WHO standards.
Quick Tips for Accurate Results
- • Weigh yourself in the morning before eating
- • Measure height without shoes
- • Use consistent units (metric or imperial)
- • BMI is a screening tool, not a diagnostic measure
Understanding BMI
What is BMI?
Body Mass Index (BMI) is a numerical value derived from your weight and height. It provides a reliable indicator of body fatness for most people and is used to screen for weight categories that may lead to health problems.
BMI Categories (WHO Standards)
The BMI Formula
For imperial units: BMI = (weight in lbs × 703) ÷ height² (inches²)
Verified Calculator
Formula source: World Health Organization (WHO) standards
This calculator uses the standard BMI formula verified against WHO classification standards used by healthcare professionals globally.
Learn more about our verification processBMI Limitations
While BMI is a useful screening tool, it has limitations:
- •Athletes: May show as overweight due to muscle mass
- •Elderly: May underestimate body fat due to muscle loss
- •Ethnicity: Different populations may have different health risk thresholds
- •Children: BMI is interpreted differently using age-specific percentiles
Always consult healthcare professionals for comprehensive health assessments.
Healthy Weight Management
Balanced Nutrition
Focus on whole foods, vegetables, lean proteins, and healthy fats
Regular Exercise
Aim for 150+ minutes of moderate activity per week
Adequate Sleep
7-9 hours of quality sleep supports metabolism
Stay Hydrated
Drink 8+ glasses of water daily
Frequently Asked Questions About BMI
Body Mass Index (BMI) is a numerical value calculated from your weight and height. The formula is: BMI = weight (kg) ÷ height² (m²). For imperial units, it's: BMI = (weight in pounds × 703) ÷ height² (inches²). BMI provides a quick screening tool to identify potential weight-related health issues.
BMI categories according to the World Health Organization (WHO) are: Underweight: BMI below 18.5; Normal weight: BMI 18.5 to 24.9; Overweight: BMI 25 to 29.9; Obesity Class I: BMI 30 to 34.9; Obesity Class II: BMI 35 to 39.9; Obesity Class III: BMI 40 and above. These ranges help identify potential health risks associated with weight.
While BMI is a useful screening tool, it has limitations. It may overestimate body fat in athletes and muscular individuals, and underestimate body fat in older persons or those who have lost muscle mass. BMI also doesn't account for factors like bone density, muscle mass, age, sex, ethnicity, or fat distribution. For a complete health assessment, consult with healthcare professionals.
A healthy BMI for adults is generally between 18.5 and 24.9. However, 'healthy' can vary based on individual factors like age, sex, ethnicity, and muscle mass. Some studies suggest that the optimal BMI may differ for different populations. Asian populations, for example, may have increased health risks at lower BMI levels. Always consider BMI as one of many health indicators.
To achieve a healthier BMI: 1) Maintain a balanced diet with appropriate calorie intake; 2) Engage in regular physical activity (150+ minutes moderate exercise weekly); 3) Stay hydrated and get adequate sleep; 4) Reduce processed foods and increase whole foods; 5) Consult healthcare providers for personalized guidance. Sustainable lifestyle changes are more effective than quick fixes.
BMI is calculated the same way for children and teens, but interpreted differently. For those under 20, BMI is expressed as a percentile compared to other children of the same age and sex. A BMI at or above the 85th percentile is considered overweight, and at or above the 95th percentile is considered obese. The CDC provides specific growth charts for pediatric BMI assessment.
About BMI Calculations
The Body Mass Index (BMI) calculator is a valuable tool for assessing whether your weight falls within a healthy range relative to your height. Developed by Belgian statistician Adolphe Quetelet in the 1830s, BMI has become a standard measurement used by healthcare professionals worldwide.
Our free BMI calculator provides instant results using the standard BMI formula: weight in kilograms divided by height in meters squared. The calculator supports both metric (kg/cm) and imperial (lbs/ft) units, making it accessible to users worldwide.
While BMI is an excellent screening tool for identifying potential weight-related health risks, it should be used as part of a comprehensive health assessment. Factors such as muscle mass, bone density, age, sex, and ethnicity can influence how BMI should be interpreted for individuals.
Regular BMI monitoring can help you track your health progress and identify trends over time. For personalized health recommendations and a complete assessment, we recommend consulting with qualified healthcare professionals.