BMI Calculator
Calculate your Body Mass Index (BMI) and understand your health status based on WHO standards.
Enter Your Details
Your BMI Results
Enter your height and weight to calculate BMI
Accurate Calculation
WHO standard BMI formula
Multiple Units
Metric and Imperial units supported
Health Insights
Detailed health status information
What is BMI (Body Mass Index)?
Body Mass Index (BMI) is a simple, widely-used screening tool that measures body fat based on your height and weight. Developed by Belgian statistician Adolphe Quetelet in the 1830s, BMI provides a quick assessment of whether you're underweight, normal weight, overweight, or obese.
While BMI doesn't directly measure body fat, it's strongly correlated with more direct measures of body fat and serves as an effective screening tool for weight-related health risks. Health professionals worldwide use BMI as a starting point for assessing health risks associated with weight.
Our BMI calculator uses the standard World Health Organization (WHO) formula and categories, providing you with accurate results and helpful health insights based on your measurements.
BMI Formula and Calculation
Metric System
BMI = Weight (kg) ÷ Height² (m)
Example: If you weigh 70 kg and are 1.75 meters tall:
BMI = 70 ÷ (1.75 × 1.75) = 70 ÷ 3.06 = 22.9
Imperial System
BMI = (Weight (lbs) × 703) ÷ Height² (inches)
Example: If you weigh 154 lbs and are 5'9" (69 inches) tall:
BMI = (154 × 703) ÷ (69 × 69) = 108,262 ÷ 4,761 = 22.7
Understanding BMI Categories
| BMI Range | Category | Health Risk |
|---|---|---|
| Below 18.5 | Underweight | May indicate malnutrition or health issues |
| 18.5 - 24.9 | Normal weight | Lowest risk of health problems |
| 25.0 - 29.9 | Overweight | Increased risk of health problems |
| 30.0 and above | Obese | High risk of health problems |
Why is BMI Important for Your Health?
Health Risk Assessment
BMI helps identify potential health risks associated with being underweight, overweight, or obese. Research shows strong correlations between BMI and various health conditions.
- Type 2 diabetes risk assessment
- Cardiovascular disease screening
- Sleep apnea evaluation
- Certain cancer risk factors
Medical Applications
Healthcare providers use BMI as a screening tool during routine check-ups and health assessments. It helps guide treatment decisions and health recommendations.
- Insurance health assessments
- Surgical eligibility criteria
- Medication dosage calculations
- Nutritional counseling guidance
BMI Limitations and Considerations
Important: BMI is a screening tool, not a diagnostic tool. It doesn't account for muscle mass, bone density, or overall body composition. Always consult healthcare professionals for comprehensive health assessments.
Athletes & Muscle Mass
BMI may categorize muscular individuals as overweight despite low body fat
Age & Gender
BMI doesn't account for age-related changes or gender differences in body composition
Bone Density
Doesn't distinguish between fat, muscle, and bone mass
How to Use Our BMI Calculator
Step-by-Step Instructions
- Choose your measurement system: Select either Metric (kg/cm) or Imperial (lbs/ft/in) based on your preference and available measurements.
- Enter your weight: Input your current weight in kilograms or pounds. For best accuracy, weigh yourself first thing in the morning.
- Enter your height: Input your height in centimeters or feet and inches. Measure without shoes for accuracy.
- View your results: The calculator automatically computes your BMI and provides your weight category with health insights.
Tips for Accurate Results
- Use consistent timing (same time of day)
- Weigh yourself on the same scale
- Wear minimal clothing
- Stand straight when measuring height
- Use precise measurements (don't round)
- Consider taking multiple measurements
Pro Tip: Track your BMI over time rather than focusing on a single measurement. This helps you monitor trends and progress toward your health goals.
Real-Life BMI Examples
Example 1: Healthy Weight
Person: 28-year-old woman
Height: 5'6" (168 cm)
Weight: 140 lbs (63.5 kg)
BMI: 22.6 (Normal weight)
This BMI indicates a healthy weight range. Continue maintaining current lifestyle with balanced nutrition and regular physical activity.
Example 2: Overweight
Person: 35-year-old man
Height: 5'10" (178 cm)
Weight: 190 lbs (86 kg)
BMI: 27.2 (Overweight)
This BMI suggests being overweight. Consider consulting a healthcare provider for personalized weight management strategies.
Frequently Asked Questions (FAQ)
Q: Is BMI accurate for everyone?
A: BMI is a useful screening tool for most adults, but it has limitations. It may not accurately reflect body composition for athletes, elderly individuals, or people with certain medical conditions. It's best used as part of a comprehensive health assessment.
Q: How often should I check my BMI?
A: For general health monitoring, checking your BMI monthly or quarterly is sufficient. If you're actively trying to lose or gain weight, weekly measurements can help track progress. Daily weighing isn't necessary and may cause unnecessary stress.
Q: Can BMI be different for different ethnicities?
A: Yes, some health organizations have suggested modified BMI ranges for certain ethnic groups. For example, Asian populations may have increased health risks at lower BMI values. Consult with healthcare providers familiar with your ethnic background for personalized guidance.
Q: What should I do if my BMI is outside the normal range?
A: If your BMI is outside the normal range, consider consulting a healthcare provider or registered dietitian. They can help develop a personalized plan that considers your overall health, medical history, and lifestyle factors beyond just BMI.
Q: Is this BMI calculator free to use?
A: Yes, our BMI calculator is completely free to use with no registration required. All calculations are performed in your browser, ensuring your privacy and data security.