BMI Calculator

For Adults (ages 20 and over):

The BMI categories (underweight, normal weight, overweight, and obesity) are standardized and do not vary with age or sex. An adult's BMI is interpreted using the same scale regardless of their age.

BMI Categories for Adults
For adults aged 20 and over, BMI is interpreted using standard weight status categories:

. Underweight: BMI less than 18.5
. Normal Weight: BMI 18.5 to 24.9
. Overweight: BMI 25 to 29.9
. Obesity Class I: BMI 30 to 34.9
. Obesity Class II: BMI 35 to 39.9
. Obesity Class III: BMI 40 and above

For Children and Teenagers (ages 2 to 19):

BMI is age and sex-specific because children's body composition varies as they grow. In this age group, BMI percentiles are used instead of fixed categories. These percentiles compare a child's BMI with that of other children of the same age and sex. For example, a child in the 85th percentile weighs more than 85% of children their age and sex.

BMI percentiles are used to compare a child's BMI with others of the same age and sex:

. Underweight: Less than the 5th percentile
. Healthy Weight: 5th to 85th percentile
. Overweight: 85th to 95th percentile
. Obesity: 95th percentile and above

The BMI is calculated using the following formula:

Metric Units: BMI=(Weight in kilograms) /(Height in meters)2

Imperial Units: BMI=(Weight in pounds×703) / (Height in inches)2

How is BMI Calculated?

Why is BMI Important?

BMI is a useful initial indicator to assess whether an individual may be at risk for health issues related to underweight or overweight status, such as:
Underweight Risks: Malnutrition, osteoporosis, anemia, and weakened immune system.
Overweight and Obesity Risks: Type 2 diabetes, hypertension, cardiovascular diseases, certain cancers, and joint problems.

Limitations of BMI

While BMI is a convenient tool, it has several limitations:
Does Not Measure Body Fat Directly: It doesn't differentiate between weight from fat and muscle.
Not Accurate for All Populations: May not be precise for athletes, pregnant women, the elderly, or certain ethnic groups.
Does Not Account for Fat Distribution: Central obesity (fat around the abdomen) poses a higher health risk than fat distributed elsewhere, which BMI does not consider.

Complementary Measures

To get a more comprehensive assessment of health risks, BMI should be used alongside other measurements:
Waist Circumference: Indicates abdominal fat content.
Body Fat Percentage: Measured using skinfold measurements, bioelectrical impedance, or DEXA scans.
Lifestyle Factors: Diet, physical activity, smoking, and alcohol consumption.