BMI Calculator
Calculate your Body Mass Index (BMI) using height and weight to assess weight status.
The Body Mass Index (BMI) Calculator is a versatile tool to assess an individual's body weight relative to their height, considering age and gender for a more nuanced interpretation, especially for children and adolescents.
⚖️ How It Works
To calculate BMI, you need to provide:
- Unit System: Choose Metric or Imperial.
- Metric System: Height is input in centimeters (cm) and weight in kilograms (kg).
- Imperial System: Height is input in feet (ft) and inches (in), and weight in pounds (lbs).
- Age: Your age in years (minimum 2 years).
- Gender: Male or Female. Gender is particularly important for interpreting BMI in children and teens.
- Height & Weight: Based on your selected unit system.
The calculator uses standard formulas:
- Metric Formula:
BMI = weight (kg) / (height (m))² - Imperial Formula:
BMI = (weight (lb) / (height (in))²) × 703
📊 BMI Interpretation & Categories
BMI interpretation varies significantly based on age:
Adults (Age 20+)
For adults, BMI is categorized as follows:
| Category | BMI Range |
|---|---|
| Underweight | < 18.5 |
| Normal weight | 18.5 – 24.9 |
| Overweight | 25 – 29.9 |
| Obesity | ≥ 30 |
Children & Teens (Age 2-19)
For children and adolescents, BMI is interpreted differently. It's plotted on BMI-for-age percentile growth charts developed by organizations like the CDC and WHO. These charts account for age and gender because body fatness changes as children grow.
This calculator provides a BMI value and a simplified category for children and teens. The categories are:
- Underweight (Simplified)
- Healthy weight (Simplified)
- Overweight (Simplified)
- Obese (Simplified)
Important: The simplified categories for children are for illustrative purposes only and are NOT a substitute for a clinical assessment using official BMI-for-age percentile charts. Always consult a healthcare provider for an accurate interpretation of a child's BMI.
💡 Common Use Cases
- Health Screening: Initial indicator of potential weight-related health risks for adults and children.
- Fitness Tracking: Monitoring changes, though BMI doesn't distinguish muscle from fat.
- Pediatric Growth Monitoring: When used with percentile charts, helps track a child's growth pattern.
✨ Features
- Inputs for age and gender for more tailored results.
- Flexible unit system (Metric/Imperial).
- Clear input fields and instant calculation.
- Display of BMI value and age-appropriate category (standard for adults, simplified for children).
- Visual feedback for the BMI category.
- Disclaimer for child BMI interpretation emphasizing the need for professional assessment.
⚠️ Important Considerations
- BMI is a screening tool, not a diagnostic one. It does not directly measure body fat.
- It may not be accurate for athletes, pregnant women, or individuals with certain medical conditions.
- For children and teens, BMI must be interpreted in the context of age and gender using percentile charts.
- Always consult a healthcare professional for a comprehensive health assessment and advice.
Use this calculator as a starting point to understand weight status, and discuss any concerns with a doctor or pediatrician.