BMI Calculator

Calculate your Body Mass Index (BMI) to assess your weight status. BMI is a simple calculation using your height and weight to estimate body fat.

What is BMI?

Body Mass Index (BMI) is a measure of body fat based on height and weight. It's calculated by dividing weight in kilograms by height in meters squared. BMI provides a simple numeric measure that helps categorize individuals into weight categories: underweight, normal weight, overweight, or obese.

How BMI Works

BMI is calculated using the formula: BMI = weight (kg) / height (m)². The result is a number that falls into one of four categories:

  • Underweight: BMI less than 18.5
  • Normal weight: BMI 18.5 to 24.9
  • Overweight: BMI 25 to 29.9
  • Obese: BMI 30 or higher

Who Should Use BMI?

BMI is useful for most adults aged 18-65 as a screening tool. It's commonly used by healthcare professionals to identify potential weight problems. However, BMI has limitations and doesn't directly measure body fat or account for muscle mass, bone density, or body composition.

BMI Limitations

BMI doesn't distinguish between fat and muscle mass. Athletes with high muscle mass may have a high BMI but low body fat. Similarly, older adults may have normal BMI but higher body fat percentage. BMI also doesn't account for fat distribution, which is important for health risks.

Examples

Example 1: A person who is 175 cm tall and weighs 70 kg

BMI = 70 / (1.75)² = 22.9 (Normal weight)

Example 2: A person who is 5'6" (167.6 cm) and weighs 200 lbs (90.7 kg)

BMI = 90.7 / (1.676)² = 32.3 (Obese)

Example 3: A person who is 160 cm tall and weighs 45 kg

BMI = 45 / (1.60)² = 17.6 (Underweight)

Understanding Your Results

If your BMI falls outside the normal range, consider consulting with a healthcare professional. They can help you understand your results in context and develop a plan if needed. Remember, BMI is just one indicator of health and should be considered alongside other factors like diet, physical activity, and family history.

Medical Disclaimer: This calculator is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

Frequently Asked Questions

What is a healthy BMI?

A healthy BMI typically falls between 18.5 and 24.9. This range is associated with the lowest risk of health problems for most people.

Is BMI accurate for everyone?

BMI is a useful screening tool but has limitations. It may overestimate body fat in muscular individuals and underestimate it in older adults who have lost muscle mass.

Can BMI be different for men and women?

The BMI formula is the same for both men and women, but the health implications may differ. Women typically have higher body fat percentages than men at the same BMI.

What should I do if my BMI is high?

If your BMI indicates overweight or obesity, consult with a healthcare professional. They can help you develop a safe and effective plan that may include diet, exercise, and lifestyle changes.

Does BMI apply to children?

BMI calculations for children and teens use the same formula but are interpreted differently using age and sex-specific percentile charts. This calculator is designed for adults.

Learn more about calculations

Understanding how calculations work helps you use them more effectively. Our guide to how online calculators work explains the mathematical principles behind tools like this BMI calculator. For health metrics specifically, learn about calculator accuracy and limitations to understand when to consult healthcare professionals. You can also explore our complete guide to free online calculators for more resources.

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