BMI Calculator - Body Mass Index Calculator
Calculate your Body Mass Index (BMI) instantly and get comprehensive health insights including weight categories, health risk assessment, and ideal weight ranges.
BMI Calculator Form
BMI is calculated using the following formulas:
Metric: BMI = weight(kg) / height(m)²
Imperial: BMI = 703 × weight(lb) / height(in)²
BMI is a screening tool, but it does not diagnose body fatness or health. The relation between BMI and body fat varies by sex, age, and fitness level.
BMI Calculator Ready
Enter your height and weight to calculate BMI
BMI (Body Mass Index) is a measurement of a person's weight with respect to their height. It's a reliable indicator to assess whether your weight is in healthy proportion to your height and identify potential health risks.
Key Features of Our BMI Calculator
Instant Results
Get your BMI calculated instantly with accurate results and comprehensive health insights.
Dual Unit Support
Calculate BMI using both metric (kg/cm) and imperial (lbs/in) measurement systems.
Health Risk Assessment
Understand your health risks with detailed BMI category explanations and recommendations.
Ideal Weight Range
Discover your ideal weight range based on your height for optimal health.
Visual BMI Chart
Interactive BMI chart showing all categories with your current position highlighted.
Free & Private
Completely free to use with no registration required. Your data stays private and secure.
Understanding Body Mass Index (BMI)
Body Mass Index (BMI) is a numerical value derived from a person's weight and height. It provides a simple way to classify weight status into categories that may indicate health risks. BMI is widely used as a screening tool to identify potential weight problems in adults.
BMI Categories and Health Risks
Severe Thinness
BMI: Less than 16
Very severe health riskModerate Thinness
BMI: 16 - 16.9
Severe health riskMild Thinness
BMI: 17 - 18.4
Moderate health riskNormal Weight
BMI: 18.5 - 24.9
Low health riskOverweight
BMI: 25 - 29.9
Enhanced health riskObese Class I
BMI: 30 - 34.9
High health riskObese Class II
BMI: 35 - 39.9
Very high health riskObese Class III
BMI: 40 or higher
Extremely high health riskLimitations of BMI
While BMI is a useful screening tool, it has several limitations:
Muscle mass: BMI doesn't distinguish between muscle and fat. Athletes and people with high muscle mass may have a high BMI despite having healthy body fat levels.
Body composition: BMI doesn't account for differences in bone density, body fat distribution, or proportion of fat to lean mass.
Age and sex: BMI interpretation should consider age, sex, ethnicity, and muscle mass. The same BMI may indicate different levels of body fat for different individuals.
Pregnancy: BMI is not applicable for pregnant women.
Using BMI Results
BMI is just one factor in evaluating health risks. For a comprehensive assessment, consider:
Waist circumference: Excess fat around the waist increases health risks more than fat elsewhere.
Lifestyle factors: Diet quality, physical activity level, and smoking status.
Family history: Genetic factors that may increase disease risk.
Other health metrics: Blood pressure, cholesterol levels, and blood sugar levels.
Frequently Asked Questions (FAQ)
What is BMI and how is it calculated?
BMI (Body Mass Index) is a measure of body fat based on height and weight that applies to adult men and women. It's calculated as weight in kilograms divided by height in meters squared (kg/m²). For imperial units, the formula is: 703 × weight in pounds divided by height in inches squared.
What are the different BMI categories?
BMI categories are: Underweight (below 18.5), Normal weight (18.5-24.9), Overweight (25-29.9), Obese Class I (30-34.9), Obese Class II (35-39.9), and Obese Class III (40 and above). Each category indicates different health risk levels.
Is BMI accurate for everyone?
BMI is a useful screening tool but has limitations. It doesn't distinguish between muscle and fat, doesn't account for bone density or body fat distribution, and may not be accurate for athletes, elderly individuals, or pregnant women. It's best used as one factor among many in health assessment.
How often should I calculate my BMI?
For general health monitoring, calculating BMI monthly or quarterly is sufficient. If you're actively trying to lose or gain weight, weekly calculations can help track progress. However, focus on overall health trends rather than daily fluctuations.
What should I do if my BMI is outside the normal range?
If your BMI is outside the normal range (18.5-24.9), consider consulting a healthcare professional. They can provide personalized advice based on your overall health, medical history, and individual circumstances. Gradual lifestyle changes in diet and exercise are typically recommended.
Can BMI be used for children and teenagers?
BMI calculations for children and teenagers (ages 2-19) use age and sex-specific percentiles rather than standard adult categories. This calculator is designed for adults aged 20 and older. For children, consult pediatric BMI charts and healthcare providers.
What factors can affect BMI accuracy?
Several factors can affect BMI accuracy: muscle mass (athletes may have high BMI but low body fat), age (muscle mass decreases with age), ethnicity (different populations have varying health risks at the same BMI), and pregnancy or medical conditions affecting weight distribution.
Is this BMI calculator free to use?
Yes, our BMI calculator is completely free to use with no registration required. Your data is processed locally in your browser and is not stored or transmitted to our servers, ensuring complete privacy and security.
How to Use the BMI Calculator
- 1
Select Your Unit System
Choose between Metric (kg/cm) or Imperial (lbs/in) units based on your preference and familiarity.
- 2
Enter Your Height
Input your height in centimeters (metric) or inches (imperial). Ensure accuracy for precise BMI calculation.
- 3
Enter Your Weight
Input your current weight in kilograms (metric) or pounds (imperial). Use your most recent accurate measurement.
- 4
Calculate and Review Results
Click "Calculate BMI" to get your results including BMI value, category, health risk assessment, and ideal weight range.