Advanced BMI calculator for women, men and children

Understanding Your BMI Results

How BMI is Calculated

Body Mass Index (BMI) is calculated using a simple mathematical formula that takes into account your height and weight:

BMI = weight (kg) / (height (m))²

For example, if you are 175 cm tall (1.75 m) and weigh 70 kg, your BMI would be calculated as:

70 ÷ (1.75 × 1.75) = 22.9

BMI Categories for Adults (20+ years)

BMI Range	Category	Health Risk
Below 18.5	Underweight	Possible nutritional deficiency and osteoporosis
18.5 - 24.9	Normal weight	Low risk (healthy range)
25.0 - 29.9	Overweight	Moderate risk of developing heart disease, high blood pressure, diabetes
30.0 and above	Obese	High risk of developing heart disease, high blood pressure, diabetes, certain cancers

BMI Interpretation for Children and Teens (2-19 years)

For children and teens, BMI is interpreted differently than for adults because their body composition varies by age and gender. Pediatricians use BMI-for-age percentiles:

BMI Percentile	Category
Less than 5th percentile	Underweight
5th to 85th percentile	Healthy weight
85th to 95th percentile	Overweight
95th percentile or higher	Obese

Limitations of BMI

While BMI is a useful screening tool, it has limitations:

Doesn't directly measure body fat
May overestimate body fat in muscular individuals
May underestimate body fat in older adults who have lost muscle mass
Doesn't account for differences in body composition between ethnic groups

Why Age and Gender Matter

Children and teens grow at different rates, so BMI must be considered relative to others of the same age and gender. For adults, gender affects body composition - men typically have more muscle mass than women at the same BMI level.