Adult BMI Calculator
Calculate body mass index from your height and weight, view the corresponding adult BMI category, and explore a healthy-weight range for your height.
Enter your measurements
Your result
Adult BMI categories
These categories are intended for adults. Children and teenagers require BMI-for-age assessment rather than the adult cutoffs shown below.
| Category | BMI range | General interpretation |
|---|---|---|
| Underweight | Below 18.5 | Below the standard healthy screening range |
| Healthy weight | 18.5–24.9 | Within the standard healthy screening range |
| Overweight | 25.0–29.9 | Above the standard healthy screening range |
| Obesity class 1 | 30.0–34.9 | Higher health-risk screening category |
| Obesity class 2 | 35.0–39.9 | Higher health-risk screening category |
| Obesity class 3 | 40.0 or higher | Highest standard adult BMI category |
How BMI is calculated
Metric formula
Example: 68 ÷ 1.71² = 23.3.
US formula
The calculator converts every unit option to the same underlying measurement before calculating.
What are BMI Prime and Ponderal Index?
BMI Prime is your BMI divided by 25. A value of 1 means your BMI is at the upper edge of the standard healthy range. The Ponderal Index uses height cubed instead of height squared and is included as a supplementary measurement—not as a diagnosis.
Understanding your result
Why BMI is useful
BMI is quick, inexpensive, and useful for screening weight relative to height. Health professionals may consider it together with blood pressure, laboratory results, waist measurement, medical history, physical activity, and other individual factors.
Important limitations
BMI cannot distinguish fat from muscle or bone. Muscular athletes may have a high BMI without excess body fat, while some people can have a BMI in the healthy range but still carry health risks not captured by BMI.
Seek personalized advice from a qualified health professional if your weight changes unexpectedly, you are pregnant, you have an eating disorder or chronic condition, or you are concerned about your result.
Frequently asked questions
Is BMI the same as body-fat percentage?
No. BMI uses only height and weight. It does not directly measure fat mass, lean mass, or where fat is stored.
Does age or sex change the adult BMI formula?
The adult calculation is the same, but interpretation should consider individual factors. Children and teens require age- and sex-specific percentiles.
What is a healthy BMI for adults?
The commonly used adult screening range is 18.5 to below 25. This range is general guidance and may not describe every person’s health.
Can I use this calculator during pregnancy?
Pre-pregnancy BMI may be used in pregnancy guidance, but this calculator should not be used to judge expected pregnancy weight changes. Ask your maternity-care professional for individualized guidance.
How accurate should my measurements be?
Use a recent weight and measure height without shoes. Small measurement errors can change results near a category boundary.
Sources and methodology
This tool uses the standard weight-to-height BMI formulas and common adult screening cutoffs. For additional guidance, consult the CDC overview of BMI and the World Health Organization overview of overweight and obesity.