BMI Percentile Calculator
Use this calculator to determine your Body Mass Index (BMI) and, for children and adolescents, understand its approximate percentile category. For adults, it provides a direct BMI classification.
Understanding BMI and BMI Percentiles
The Body Mass Index (BMI) is a simple calculation using a person's height and weight. The formula is BMI = kg/m², where kg is a person's weight in kilograms and m² is their height in metres squared. BMI is a screening tool that can indicate whether a person is underweight, has a healthy weight, is overweight, or is obese.
BMI for Adults (Age 20 and Older)
For adults, BMI is interpreted using standard weight status categories that are the same for men and women of all body types and ages:
- Underweight: BMI less than 18.5
- Normal or Healthy Weight: BMI 18.5 to 24.9
- Overweight: BMI 25.0 to 29.9
- Obese: BMI 30.0 or higher
While BMI is a useful screening tool, it does not measure body fat directly. Factors like muscle mass, bone density, and overall body composition can influence BMI. For example, a very muscular person might have a high BMI without being overweight.
BMI Percentiles for Children and Adolescents (Ages 2-19)
For children and adolescents, BMI is interpreted differently than for adults. Because children's body composition changes as they grow, and boys and girls differ in their growth patterns, BMI for children is age- and sex-specific. Instead of using fixed cut-off points, a child's BMI is plotted on growth charts to determine their BMI-for-age percentile.
The percentile indicates the relative position of the child's BMI among children of the same sex and age. For example, a child at the 75th percentile has a BMI greater than 75% of children of the same age and sex.
The standard weight status categories for children and adolescents are:
- Underweight: Less than the 5th percentile
- Healthy Weight: 5th percentile to less than the 85th percentile
- Overweight: 85th percentile to less than the 95th percentile
- Obese: 95th percentile or greater
Important Note: This calculator provides an *estimated* percentile category for children and adolescents based on general BMI ranges. A precise BMI percentile requires plotting the child's BMI on official growth charts, which should be done by a healthcare professional. This calculator is for informational purposes only and should not replace professional medical advice.
How to Use the Calculator
- Enter Weight: Input your weight in kilograms (e.g.,
70). - Enter Height: Input your height in centimeters (e.g.,
175). - Enter Age: Input your age in years (e.g.,
30). - Select Sex: Choose your biological sex from the dropdown menu.
- Click "Calculate": The calculator will display your BMI, its classification, and an estimated percentile category.
Examples
Example 1: Adult Male
- Weight: 85 kg
- Height: 180 cm
- Age: 35 years
- Sex: Male
- Result: BMI = 26.23 (Overweight), typically 85th to 94th percentile.
Example 2: Adolescent Female
- Weight: 50 kg
- Height: 155 cm
- Age: 14 years
- Sex: Female
- Result: BMI = 20.81 (Healthy Weight), likely between 50th and 84th percentile. (Note: This is an estimation for children/adolescents.)
Example 3: Adult Female
- Weight: 60 kg
- Height: 165 cm
- Age: 28 years
- Sex: Female
- Result: BMI = 22.04 (Normal Weight), typically 5th to 84th percentile.