Free accurate BMI calculator for adults and children. Calculate your Body Mass Index with age and gender considerations.
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 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 |
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 |
While BMI is a useful screening tool, it has limitations:
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.