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BMI Calculator

Calculate your Body Mass Index to determine your weight category and health status.

BMI Calculator

BMI Result

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Understanding Your Body Mass Index (BMI)

Body Mass Index (BMI) is a widely used health metric that estimates whether your weight is healthy for your height. It helps identify your weight category—underweight, normal, overweight, or obese—based on your height and weight. BMI is an effective tool for assessing potential health risks related to body weight.

Metric Formula: BMI = weight (kg) ÷ [height (m)]²
Imperial Formula: BMI = 703 × weight (lbs) ÷ [height (in)]²

BMI Categories for Adults (20+ years):

  • Severe Thinness: < 16
  • Moderate Thinness: 16 – 17
  • Mild Thinness: 17 – 18.5
  • Normal (Healthy Weight): 18.5 – 25
  • Overweight: 25 – 30
  • Obese Class I: 30 – 35
  • Obese Class II: 35 – 40
  • Obese Class III: > 40

BMI Categories for Children & Teens (2–20 years):

  • Underweight: < 5th percentile
  • Healthy Weight: 5th – 85th percentile
  • At Risk of Overweight: 85th – 95th percentile
  • Overweight: > 95th percentile

BMI is an important health tool used alongside other metrics to monitor your body composition and overall wellness.

Why Your BMI Matters

Knowing your BMI (Body Mass Index) helps you understand your health and fitness level. Maintaining a healthy BMI reduces risks of chronic diseases such as heart disease, type 2 diabetes, high blood pressure, and obesity. It also provides a baseline for tracking weight changes over time.

Your BMI doesn’t directly measure body fat, but it is a strong indicator of whether your weight may affect your health. For a more complete analysis, consider related tools like the Body Fat Calculator or Ideal Weight Calculator.

The BMI Calculator also computes the Ponderal Index (PI) and BMI Prime, providing additional insights about your body composition and leanness for adults and children.

Limitations of BMI

While BMI is useful, it has limitations. It does not distinguish between muscle and fat, so muscular individuals may have a high BMI despite low body fat. Older adults may have normal BMI but higher body fat. BMI should always be used alongside other health metrics.

Other measurements to pair with BMI include:

How to Maintain a Healthy BMI

Achieving a healthy BMI involves proper nutrition, regular exercise, and lifestyle habits. Follow these tips:

  • Eat a balanced diet with lean protein, fruits, vegetables, and whole grains.
  • Engage in regular exercise—at least 150 minutes of moderate activity per week.
  • Track calorie needs using the TDEE Calculator.
  • Stay hydrated and get adequate sleep to support metabolism and recovery.
  • Recalculate BMI regularly and track changes to monitor progress.

Maintaining a healthy weight improves energy, reduces disease risk, and enhances overall wellness.

Try Other Fitness Calculators

Explore these free tools to better understand your weight, BMI, body fat, and nutrition:

BMI – History