The Centers for Disease Control and Prevention provides a body mass index chart at cdc.gov. The chart assesses body fatness in the average human with respect to height and weight.
Standard weight status classifications for both men and women of all ages are used to interpret body mass index. In children and teens, the interpretation of BMI is age and sex specific, according to the CDC.
Individuals with a BMI of 18.5 or less are considered underweight, ranges from 18.5 to 24.9 are considered ideal. A BMI of 25.0 to 29.9 indicates a person is overweight; those at 30.0 or higher are considered obese.