BMI Calculator
Calculate BMI, see the standard adult category, and estimate the reference weight range for your entered height.
Body mass index
BMI result
The diagram uses 0 to 40 as its visible scale. Values above 40 are placed at the right edge while the calculated BMI remains shown above.
The reference weight range uses an adult BMI of 18.5 to 24.9 at the entered height. It is a general screening reference, not a diagnosis or direct guidance for children, pregnancy, athletes with high muscle mass, or individual medical decisions.
On this page
What the result shows
Enter height and weight in metric or US customary units. The result gives the BMI value, its standard adult category, and a reference weight range for the same height. That range uses BMI 18.5 to 24.9 and is shown in the unit system you selected.
Adult BMI category guide
| Category | BMI range | How to read it |
|---|---|---|
| Underweight | Below 18.5 | Below the standard adult reference band |
| Normal range | 18.5 to 24.9 | The band used for the reference weight range |
| Overweight | 25.0 to 29.9 | Above the standard adult reference band |
| Obesity range | 30.0 or higher | At or above the standard adult threshold |
The table shows BMI bands, not fixed weights. The tool calculates the reference weight range for BMI 18.5 to 24.9 from the height you enter, so the displayed kilograms or pounds change with height.
Formula and units
For metric input, BMI is weight in kilograms divided by height in meters squared. For US customary input, the equivalent calculation uses pounds and inches with the 703 conversion factor. The calculator does not adjust the result for age, sex, body composition, or activity level.
Use the category carefully
BMI is a height-to-weight screening index, not a direct measurement of body fat or a diagnosis. The adult categories and reference range can be misleading for children, pregnancy, athletes with high muscle mass, and some body types. Use the result as a general reference rather than a medical decision.