BMI Calculator
Calculate your Body Mass Index and determine your weight category with our free BMI calculator.
Enter Your Measurements
cm
kg
Results calculate automatically as you enter values
BMI Results
Enter your height and weight to calculate BMI.
Understanding BMI
What is BMI?
Body Mass Index (BMI) is a simple calculation using a person's height and weight. The formula is BMI = kg/m² where kg is a person's weight in kilograms and m² is their height in metres squared.
BMI Categories
- Underweight: BMI less than 18.5
- Normal weight: BMI 18.5-24.9
- Overweight: BMI 25-29.9
- Obese: BMI 30 or greater
Important Limitations
- Does not measure body fat directly
- May overestimate body fat in athletes with high muscle mass
- May underestimate body fat in older adults who have lost muscle mass
- Not suitable for pregnant women
- Should be used alongside other health assessments
Disclaimer: This calculator is for informational purposes only. Always consult with healthcare professionals for medical advice and health assessments.
Related Tools
About BMI Calculator
How It Works
- Calculates Body Mass Index using the formula: BMI = weight(kg) / height(m)²
- Supports both metric (cm/kg) and imperial (ft/in/lbs) units
- Categorizes results into standard BMI ranges
- Provides healthy weight range for your height
- Updates results automatically as you enter values
BMI Categories
- Underweight: BMI below 18.5
- Normal weight: BMI 18.5-24.9
- Overweight: BMI 25.0-29.9
- Obese: BMI 30.0 and above
Important Notes
- BMI is a screening tool, not a diagnostic measure
- Does not account for muscle mass, bone density, or body composition
- May not be accurate for athletes, pregnant women, or elderly individuals
- Consult healthcare professionals for medical advice
Common Use Cases
- General health screening and monitoring
- Weight management goal setting
- Health insurance assessments
- Medical appointment preparation
- Personal fitness tracking
Frequently Asked Questions
What is BMI and how is it calculated?
BMI (Body Mass Index) is a measure that uses your height and weight to work out if your weight is healthy. It is calculated using the formula: BMI = weight (kg) ÷ height (m)². For example, if you weigh 70kg and are 1.75m tall, your BMI would be 70 ÷ (1.75 × 1.75) = 22.9.
What are the different BMI categories?
BMI categories are: Underweight (below 18.5), Normal weight (18.5-24.9), Overweight (25.0-29.9), and Obese (30.0 and above). These categories help assess potential health risks associated with weight, though BMI should be considered alongside other health factors.
Is BMI accurate for everyone?
BMI is a useful screening tool but has limitations. It may not be accurate for athletes with high muscle mass, pregnant women, elderly individuals, or children. BMI doesn't distinguish between muscle and fat mass, so very muscular people may have high BMI despite being healthy.
Can I use this calculator with imperial units?
Yes! Our calculator supports both metric (centimeters and kilograms) and imperial (feet, inches, and pounds) units. Simply select your preferred unit system and enter your measurements. The calculator automatically converts between units and provides accurate BMI calculations.
What is a healthy BMI range?
A healthy BMI range is generally considered to be 18.5 to 24.9. However, ideal BMI can vary based on factors like age, gender, muscle mass, and ethnicity. Our calculator shows the healthy weight range for your height, but it's best to consult healthcare professionals for personalized advice.
How often should I check my BMI?
BMI can be checked periodically as part of health monitoring, especially if you're working on weight management goals. However, daily weighing isn't necessary as weight naturally fluctuates. Monthly or quarterly checks are often sufficient for most people tracking their health progress.
What should I do if my BMI is outside the normal range?
If your BMI indicates underweight, overweight, or obesity, consider consulting a healthcare professional for personalized advice. They can assess your overall health, consider other factors beyond BMI, and help create appropriate nutrition and exercise plans if needed.
Does BMI apply to children and teenagers?
BMI calculations for children and teenagers require different interpretation using age and sex-specific percentiles rather than adult categories. This calculator is designed for adults (18+ years). For children, consult pediatric growth charts and healthcare professionals.
Can muscle mass affect my BMI results?
Yes, muscle mass significantly affects BMI. Since muscle weighs more than fat, very fit individuals with high muscle mass may have BMI readings in the "overweight" range despite having low body fat. BMI should be considered alongside other health indicators like body fat percentage and fitness level.
Are there alternatives to BMI for health assessment?
Yes, alternatives include waist circumference measurement, body fat percentage, waist-to-hip ratio, and comprehensive fitness assessments. These can provide additional insights into health status. BMI is best used as one tool among many for understanding overall health and wellness.
How accurate are the healthy weight ranges shown?
The healthy weight ranges are calculated based on BMI values of 18.5-24.9 for your height, following standard medical guidelines. However, individual ideal weights can vary based on body composition, health history, and other factors. Use these ranges as general guidance rather than absolute targets.
Can I track my BMI changes over time with this calculator?
While this calculator provides instant BMI calculations, it doesn't store historical data. For tracking BMI over time, consider keeping a personal record of your measurements and BMI results. Regular monitoring can help you observe trends and progress toward health goals.