BMI Calculator

The Body Mass Index (BMI) Calculator helps you determine whether your weight is healthy for your height and age. Simply enter your details to instantly calculate your BMI value and see your corresponding weight category — underweight, healthy, overweight, or obese. Our calculator supports Metric Units (kilograms and centimeters). It also provides the Ponderal Index (PI), a complementary measure that considers height-to-weight proportion more accurately for taller or shorter individuals. Use this tool to better understand your body composition and take a step toward improving your health and fitness goals.

16 17 18.5 25 30 35 40 Underweight Normal Overweight Obesity BMI = 0

BMI (Body Mass Index) Introduction

BMI (Body Mass Index) is a quick measure of your body weight in relation to your height. It helps estimate whether you are at a healthy weight, underweight, overweight, or obese. Although BMI doesn’t directly measure body fat, it’s a reliable screening tool for most people to understand their general fitness and health status.

BMI Chart for Adults (Men and Women)

The WHO BMI chart below shows the healthy body weight ranges recommended by the World Health Organization (WHO) for adults aged 20 and above. These BMI categories apply to both men and women and serve as a global standard for assessing healthy weight levels.

Classification BMI range - kg/m2
Severe Thinness< 16
Moderate Thinness16 - 17
Mild Thinness17 - 18.5
Normal18.5 - 25
Overweight25 - 30
Obese Class I30 - 35
Obese Class II35 - 40
Obese Class III> 40

BMI Categories Children, Ages 2 to 20

For younger people, BMI is interpreted using percentiles based on age and gender, as recommended by the Centers for Disease Control and Prevention (CDC):

Category Percentile Range
Underweight<5%
Healthy weight5% - 85%
At risk of overweight85% - 95%
Overweight>95%

Why BMI Matters

Maintaining a healthy BMI lowers the risk of many serious health problems, such as:

  • High blood pressure and heart disease
  • Type 2 diabetes
  • Stroke    
  • Joint pain and osteoarthritis
  • Certain cancers (breast, colon, liver, etc.)
  • Sleep apnea and respiratory issues
  • Depression and low energy

On the other hand, being underweight can also cause:

  • Nutrient deficiencies and anemia
  • Weak bones (osteoporosis)
  • Low immunity
  • Hormonal imbalance and
  • reproductive problems
  • Growth issues in children
  • Increased risk of injury or surgical complication

Limitations of BMI

BMI is a useful general indicator but not a perfect measure.

 It doesn’t differentiate between muscle, bone, and fat, so:

  • Athletes or muscular people may appear overweight even if they’re lean.
  • Older adults may have higher body fat despite a “normal” BMI.
  • Women typically have more body fat than men with the same BMI.

For the most accurate understanding of your health, use BMI along with body fat percentage, waist circumference, and overall activity level.