BMI Calculator
Calculate your Body Mass Index (BMI), healthy weight range and BMI category based on your height and weight.
Calculate Your BMI
Your BMI Result
Healthy starts 25
Overweight 30
Obesity 40 50
Adult BMI Categories
For adults, BMI is generally interpreted using fixed BMI categories. These categories are intended for adults age 20 and older.
| BMI Range | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy Weight |
| 25.0 – 29.9 | Overweight |
| 30.0 – 34.9 | Obesity – Class 1 |
| 35.0 – 39.9 | Obesity – Class 2 |
| 40.0 or higher | Obesity – Class 3 |
BMI for Children and Teenagers
BMI is calculated from height and weight in children and teenagers just as it is in adults. However, the result is interpreted differently because children and teenagers are still growing.
For ages 2 through 19, BMI is interpreted using a BMI-for-age percentile. The percentile compares a child's BMI with other children of the same age and sex.
| BMI-for-Age Percentile | Category |
|---|---|
| Below the 5th percentile | Underweight |
| 5th to below 85th percentile | Healthy Weight |
| 85th to below 95th percentile | Overweight |
| 95th percentile or higher | Obesity |
A BMI that may be typical for an adult cannot automatically be considered healthy for a growing child. Children's body composition changes with age and differs between boys and girls, so BMI must be interpreted relative to age and sex.
BMI Age Guide
Children under 2 years
Standard BMI categories are not normally used for infants under 2 years. Growth is generally assessed using appropriate growth measurements and clinical growth charts.
Children and teenagers: 2–19 years
BMI-for-age percentiles are used. The child's age, sex, height and weight are important when interpreting the result.
Adults: 20 years and older
Adult BMI categories are generally used. A BMI below 18.5 is classified as underweight, 18.5–24.9 as healthy weight, 25.0–29.9 as overweight and 30 or higher as obesity.
Older adults
BMI remains a screening measure, but BMI alone does not describe muscle mass, fat distribution, physical fitness, or other aspects of health. Additional factors may be important when interpreting BMI in older adults.
What Is BMI?
Body Mass Index (BMI) is a calculated measure of weight relative to height. For adults, it is calculated by dividing weight in kilograms by height in meters squared.
BMI = weight (kg) ÷ height² (m)
BMI is useful as a general screening measure, but it does not directly measure body fat. A person's muscle mass, body composition, health history and other factors can affect how BMI should be interpreted.