Home
Back
BMI Formula:
| From: | To: |
Body Mass Index (BMI) is a simple index of weight-for-height that is commonly used to classify underweight, overweight and obesity in adults. It is defined as a person's weight in kilograms divided by the square of their height in meters (kg/m²).
The calculator uses the BMI formula:
Where:
Explanation: The formula calculates body mass index by dividing weight by the square of height, providing a standardized measurement of body fatness.
Details: BMI provides a simple numeric measure of a person's thickness or thinness, allowing health professionals to discuss weight problems more objectively with their patients. It is used to screen for weight categories that may lead to health problems.
Tips: Enter weight in kilograms and height in meters. All values must be valid (weight > 0, height > 0). For accurate results, measure weight and height without shoes and heavy clothing.
Q1: What are the standard BMI categories?
A: Underweight: BMI < 18.5, Normal weight: BMI 18.5-24.9, Overweight: BMI 25-29.9, Obesity: BMI ≥ 30.
Q2: Is BMI accurate for everyone?
A: BMI may not accurately reflect body fatness in athletes (who have more muscle mass), the elderly (who may have lost muscle mass), or certain ethnic groups.
Q3: Can children use this calculator?
A: This calculator is designed for adults. Children and teens need age and sex-specific BMI percentiles as their body composition varies with age and differs between boys and girls.
Q4: What's the difference between kg and pounds for BMI?
A: The formula is the same conceptually, but requires conversion factors when using pounds and inches: BMI = (weight in pounds × 703) / (height in inches)².
Q5: Should BMI be the only measure of healthy weight?
A: No, BMI should be used as a screening tool, not a diagnostic of body fatness or health. Other factors like waist circumference, diet, physical activity, and family history should be considered.