BMI Calculator

Calculate your Body Mass Index (BMI) to assess your weight status

BMI Calculator

Calculate your Body Mass Index

Instructions

Enter your height and weight to calculate your BMI. Choose between metric or imperial units.

BMI Categories:

  • Underweight: Below 18.5
  • Normal weight: 18.5-24.9
  • Overweight: 25-29.9
  • Obese: 30 and above

⚠️ Medical Disclaimer

This BMI calculator is for informational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. BMI may not be accurate for athletes, pregnant women, elderly, or children. Always consult with a qualified healthcare provider before making any health-related decisions.

Understanding BMI: A Comprehensive Guide

What is BMI?

Body Mass Index (BMI) is a screening tool used to categorize individuals into weight status categories. It's calculated by dividing a person's weight by the square of their height. BMI provides a simple numeric measure that allows healthcare professionals to discuss weight categories with patients.

BMI Formula:

Metric: BMI = weight (kg) / height (m)²

Imperial: BMI = (weight (lbs) / height (in)²) × 703

BMI Categories Explained

Underweight (BMI < 18.5)

May indicate malnutrition or underlying health conditions

Normal Weight (BMI 18.5-24.9)

Associated with lowest risk of weight-related diseases

Overweight (BMI 25-29.9)

Increased risk of cardiovascular disease and diabetes

Obese (BMI ≥ 30)

Significantly increased risk of serious health conditions

BMI Limitations and Considerations

⚠️ BMI Doesn't Measure

  • • Body fat percentage
  • • Muscle mass distribution
  • • Bone density
  • • Overall body composition
  • • Fat distribution patterns
  • • Metabolic health markers

👥 Special Populations

Athletes & Bodybuilders

High muscle mass can result in elevated BMI despite low body fat

Elderly Adults

Age-related muscle loss may affect BMI interpretation

Children & Teens

Require age and sex-specific percentile charts

🌍 Ethnic Considerations

Asian Populations: Higher risk at lower BMI levels

Pacific Islanders: Naturally higher muscle mass

African Americans: Different body composition patterns

Always consider ethnic background when interpreting BMI results.

Health Implications by BMI Category

Underweight Health Risks

Potential Causes

  • • Eating disorders (anorexia, bulimia)
  • • Chronic diseases (cancer, hyperthyroidism)
  • • Medications affecting appetite
  • • High metabolism or genetics

Associated Risks

  • • Weakened immune system
  • • Osteoporosis and fractures
  • • Fertility problems
  • • Delayed wound healing

Overweight/Obesity Health Risks

Cardiovascular Risks

  • • High blood pressure
  • • Heart disease
  • • Stroke
  • • High cholesterol

Metabolic Risks

  • • Type 2 diabetes
  • • Metabolic syndrome
  • • Sleep apnea
  • • Certain cancers

Alternative Health Measurements

Waist Circumference

Measures abdominal fat, which is more strongly linked to health risks than total body weight.

High Risk (Men): > 40 inches (102 cm)

High Risk (Women): > 35 inches (88 cm)

Body Fat Percentage

More accurate measure of body composition than BMI alone.

Healthy (Men): 10-20%

Healthy (Women): 18-28%

Waist-to-Hip Ratio

Indicates fat distribution patterns and metabolic health risks.

Low Risk (Men): < 0.90

Low Risk (Women): < 0.85

Healthy Weight Management Strategies

For Weight Loss

Nutrition

  • • Create a moderate caloric deficit (300-500 calories)
  • • Focus on whole, nutrient-dense foods
  • • Control portion sizes
  • • Stay hydrated with water

Physical Activity

  • • 150+ minutes moderate aerobic activity weekly
  • • 2+ days strength training per week
  • • Increase daily movement and steps
  • • Find activities you enjoy

For Weight Gain

Healthy Weight Gain

  • • Increase caloric intake with nutritious foods
  • • Eat frequent, smaller meals
  • • Include healthy fats and proteins
  • • Consider liquid calories (smoothies, shakes)

Build Muscle Mass

  • • Focus on resistance training
  • • Ensure adequate protein intake
  • • Allow proper recovery between workouts
  • • Consider working with a trainer

When to Consult Healthcare Professionals

Consult Your Doctor If:

  • • Your BMI is outside the normal range
  • • You have rapid, unexplained weight changes
  • • You have symptoms of eating disorders
  • • You have risk factors for chronic diseases
  • • You need guidance on healthy weight management
  • • You're considering significant lifestyle changes

Healthcare Team Members:

Primary Care Physician

Overall health assessment and medical guidance

Registered Dietitian

Personalized nutrition counseling and meal planning

Exercise Physiologist

Safe and effective exercise program design

Mental Health Professional

Support for eating disorders or psychological factors