BMI Calculator
Calculate your Body Mass Index (BMI) to determine if you are at a healthy weight based on your height.
BMI Calculator
Calculate your Body Mass Index (BMI)
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Reference Ranges
May indicate malnutrition or other health issues.
Optimal health weight range.
Increased risk of health complications.
High risk of severe weight-related health issues.
What is Body Mass Index (BMI)?
Body Mass Index (BMI) is a widely used measurement that compares a person's weight to their height. It provides a simple and fast method to estimate body fat and categorize individuals into weight groups that are associated with different health risks. While BMI does not measure body fat directly, research has shown that it correlates strongly with more direct measures of body fat, such as dual-energy x-ray absorptiometry (DXA) and underwater weighing.
The calculation is simple: BMI is defined as body mass divided by the square of the body height, universally expressed in units of kg/m².
BMI Categories and Health Risks
The World Health Organization (WHO) and the National Institutes of Health (NIH) define the following BMI categories for adults:
- Underweight (BMI < 18.5): May indicate malnutrition, an eating disorder, or other underlying health issues. Risks include weakened immune system, fragile bones, and fatigue.
- Normal weight (BMI 18.5 – 24.9): Associated with the lowest health risks and optimal well-being.
- Overweight (BMI 25.0 – 29.9): Indicates excess weight. Individuals in this category have an increased risk of developing cardiovascular diseases, type 2 diabetes, and hypertension.
- Obesity Class I (BMI 30.0 – 34.9): Moderate risk of weight-related health complications.
- Obesity Class II (BMI 35.0 – 39.9): High risk of severe weight-related health issues.
- Obesity Class III (BMI ≥ 40.0): Very high risk, often classified as severe or morbid obesity.
Limitations of BMI
While BMI is a useful screening tool, it has limitations, such as not distinguishing between muscle mass and fat, not capturing fat distribution (like visceral fat), and failing to account for age and sex variations.
Frequently Asked Questions
How is BMI calculated?
BMI is calculated by dividing your weight in kilograms by the square of your height in meters.
Is BMI accurate for athletes?
Not always. Athletes often have high muscle mass, which weighs more than fat. This can result in a high BMI even if their body fat percentage is very low.
What is a healthy BMI?
A healthy BMI for most adults is typically between 18.5 and 24.9.
Does BMI apply to children?
For children and teens, BMI is age- and sex-specific. A specialized BMI percentile chart is used rather than the standard adult categories.
Should I only rely on BMI for my health?
No, BMI is just a screening tool. Other factors like waist circumference, diet, physical activity, and blood work are essential for a complete health assessment.
Medical Disclaimer: This calculator is for informational and educational purposes only. It is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider. Read full disclaimer →