Adult BMI Categories: Underweight, Healthy Weight, Overweight, and Obesity
Review the CDC adult BMI category ranges for people age 20 and older and why the result is a screening measure rather than a diagnosis.
CDC BMI Categories for Adults Age 20 and Older
- Underweight: below 18.5
- Healthy Weight: 18.5 to 24.9
- Overweight: 25.0 to 29.9
- Obesity: 30.0 and above
These are the categories displayed by the CDC Adult BMI Calculator. They apply to adults age 20 and older. Children and teens require age- and sex-specific BMI percentiles instead of these fixed ranges.
A Screening Category Is Not a Diagnosis
BMI is a calculated measure of weight relative to height. It is one potential screening indicator, not a diagnosis of disease, a direct body-fat measurement, or a prescription for treatment.
What the Categories Do Not Capture
- Muscle mass — athletes often score "overweight" despite low body fat
- Where fat is distributed on the body
- Age-related changes in body composition
- Differences that can exist across population groups
Reading Your Result in Context
A small difference around a category boundary does not by itself diagnose health or prescribe treatment. A healthcare professional can interpret BMI alongside medical history, health behaviours, examination findings, laboratory results, and other relevant information.
Conclusion
Use the Adult BMI Calculator to see a weight-for-height screening result and corresponding adult category. Do not use it for a child or teenager, and do not treat the result as a diagnosis, body-fat measurement, or personalised health recommendation.