What this calculator does
Body roundness index (BRI) works out estimates body shape and visceral fat from waist and height, an alternative to BMI. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
FormulaBRI = 364.2 − 365.5 × √(1 − (WC/(2π))² / (0.5×height)²), WC and height in metres
The inputs explained
| Field | What to enter |
|---|---|
| Waist circumference (cm) | A number, measured in cm. Starts at 85. |
| Height (cm) | A number, measured in cm. Starts at 175. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with waist circumference
Every other input is held at the calculator’s starting values while waist circumference varies. Select any row to load that scenario into the calculator.
How the answer changes with waist circumference
| Waist circumference (cm) | Body roundness index | Source | Note |
|---|---|---|---|
| 42.5 | -0.21 | Thomas et al. (2013), Obesity, a geometric model of body shape from waist and height. | Higher BRI has been associated with higher visceral fat and cardiometabolic risk in population studies; it is not a diagnosis. |
| 63.75 | 1.17 | Thomas et al. (2013), Obesity, a geometric model of body shape from waist and height. | Higher BRI has been associated with higher visceral fat and cardiometabolic risk in population studies; it is not a diagnosis. |
| 85 | 3.09 | Thomas et al. (2013), Obesity, a geometric model of body shape from waist and height. | Higher BRI has been associated with higher visceral fat and cardiometabolic risk in population studies; it is not a diagnosis. |
| 128 | 8.74 | Thomas et al. (2013), Obesity, a geometric model of body shape from waist and height. | Higher BRI has been associated with higher visceral fat and cardiometabolic risk in population studies; it is not a diagnosis. |
| 170 | 16.61 | Thomas et al. (2013), Obesity, a geometric model of body shape from waist and height. | Higher BRI has been associated with higher visceral fat and cardiometabolic risk in population studies; it is not a diagnosis. |
| 255 | 40.39 | Thomas et al. (2013), Obesity, a geometric model of body shape from waist and height. | Higher BRI has been associated with higher visceral fat and cardiometabolic risk in population studies; it is not a diagnosis. |