BMI Calculator Online | Body Mass Index Calculator
Calculate your Body Mass Index (BMI) with our comprehensive weight health calculator and obesity calculator. Determine if you are underweight, normal weight, overweight, or obese using our body mass index calculator and healthy weight calculator for accurate health assessment.
BMI Calculator
Height (cm):
Weight (kg):
BMI Formulas
Metric: BMI = weight(kg) / height(m)²
Imperial: BMI = [weight(lb) / height(in)²] × 703
Body Mass Index is calculated by dividing your weight by the square of your height. The result is interpreted using standard weight status categories.
BMI Categories
- Below 18.5
Underweight
- 18.5 - 24.9
Normal weight
- 25.0 - 29.9
Overweight
- 30.0 - 34.9
Obesity (Class 1)
- 35.0 - 39.9
Obesity (Class 2)
- 40.0 and above
Extreme Obesity (Class 3)
About BMI
Body Mass Index (BMI) is widely used as a screening tool to categorize individuals into weight status categories. Healthcare professionals use BMI to identify potential weight problems in patients. It provides a simple numeric measure of a person's thickness or thinness, allowing health professionals to discuss weight problems more objectively.
Many people use BMI calculators for personal health assessments to understand if they fall within a healthy weight range. BMI is also commonly used in epidemiological studies to assess obesity rates within populations, and in fitness and wellness programs to set baseline measurements for weight management goals.
Key Terms
- BMI: Body Mass Index
- Weight: Body weight in kilograms (kg) or pounds (lb)
- Height: Height in meters (m) or inches (in)
- Result: A numerical value used to categorize a person as underweight (<18.5), normal weight (18.5-24.9), overweight (25-29.9), or obese (≥30)
Limitations of BMI
While BMI is a useful screening tool, it has several important limitations to consider:
- Muscle mass not considered: BMI doesn't distinguish between muscle and fat. Athletes with high muscle mass may be categorized as "overweight" despite having healthy body fat percentages.
- Age and sex differences: BMI doesn't account for natural body composition differences between men and women, or changes that occur with aging.
- Ethnicity variations: Different ethnic groups may have different body compositions and health risks at the same BMI level.
- Fat distribution ignored: BMI doesn't indicate where fat is stored. Abdominal fat (measured by waist circumference) is a better predictor of certain health risks than overall BMI.
For a comprehensive health assessment, BMI should be used alongside other measurements such as waist circumference, body fat percentage, and clinical evaluations by healthcare professionals.