What Is a Healthy BMI? How to Calculate and Interpret It
Automated technical check: . Scope and review policy
The CDC's adult BMI screening category called healthy weight is 18.5 to below 25, for ages 20 and older. It is a category of a height-and-weight calculation, not a diagnosis. The BMI Calculator uses those adult cutoffs; it does not calculate children's growth-chart percentiles.
Calculate the number
BMI = weight in kilograms / height in meters squared. At 170 cm and 70 kg, the calculation is 70 / (1.70 x 1.70) = 24.2 after rounding. Convert the units before applying the formula; entering centimeters where meters are expected changes the denominator by a factor of 10,000.
Read boundaries without rounding errors
| Category | Unrounded BMI |
|---|---|
| Underweight | Below 18.5 |
| Healthy weight | 18.5 to below 25 |
| Overweight | 25 to below 30 |
| Obesity | 30 or higher |
The calculator classifies the unrounded result, then rounds the displayed number to one decimal. A displayed 25.0 might be just below or above the cutoff before rounding. Do not infer a meaningful change in health from a tiny movement across a display boundary.
What this cannot tell you
The same BMI can come from different amounts of muscle, fat and bone. It does not measure where fat is distributed, assess fitness, or explain symptoms. A category alone cannot establish whether a particular person's weight is suitable. These standard adult bands also do not calculate pregnancy weight-gain guidance, ethnicity-specific clinical thresholds or pediatric percentiles.
The circumference body-fat estimate asks a different question, but is another model rather than a definitive assessment. Likewise, averaging height-based weight formulas does not turn them into a personal target.
Use the result as a question, not a prescription
Measure height and weight carefully, choose the matching unit mode, and check the input values when a result seems unexpected. Invalid or nonpositive measurements produce no estimate. For a health decision, discuss the result alongside your history and other assessments with a qualified clinician. This guide does not prescribe weight loss, weight gain or a calorie intake.
Sources and Scope
Technical example checks are not independent professional review. Sources were checked for the statements above on October 6, 2026.