Adult BMI boundaries
BMI compares body weight with height squared. The table is an adult screening reference, not a measurement of body fat or a diagnosis of health.
| BMI range | Category | Use carefully because |
|---|---|---|
| <18.5 | Underweight | BMI does not explain cause |
| 18.5-24.9 | Healthy range | Still needs health context |
| 25.0-29.9 | Overweight | Muscle can distort the result |
| 30.0+ | Obesity range | Waist and clinical context matter |
The healthy-weight band starts at 18.5 and ends below 25; the next band starts at 25 and ends below 30. Labels such as 24.9 are short display conventions. Use the underlying value when deciding which side of a boundary a result falls on.
Calculate a BMI before reading its row
At 72 kg and 1.75 m, BMI = 72 ÷ (1.75 × 1.75) = 23.51, displayed as 23.5. That falls within the 18.5-to-below-25 band. The number alone does not distinguish muscle from fat.
Who the chart describes
The linked CDC reference uses these categories for adults aged 20 and over. Children and teenagers require age- and sex-specific assessment. Pregnancy, muscular builds and individual health circumstances also require context beyond this table.
Frequently asked questions
Does a BMI in the healthy-weight band prove good health?
No. BMI is one screening measure. It does not assess body composition, fitness, blood pressure or other clinical information.
Should I round BMI before choosing a category?
Use the unrounded value for the boundary comparison, then round it for display. The category changes at 18.5, 25 and 30.