Body Roundness Index Calculator
Calculate your Body Roundness Index (BRI) from height and waist, a body-shape measure of abdominal fat.
About the Body Roundness Index Calculator
Enter your height and waist circumference (at the navel) in the same units. The calculator gives your Body Roundness Index and where it sits on the risk curve from a 2024 US study.
BRI (Thomas et al., 2013) models the body as an ellipse to estimate how round you are around the middle, which reflects visceral fat better than BMI. Values usually range from about 1 to 16. A 2024 study of US adults found a U-shaped link with death risk: lowest at roughly 4.5–5.5, higher at both very low and high values.
The formula
BRI = 364.2 − 365.5 × √(1 − (waist ÷ 2π)² ÷ (½ × height)²)
Worked example
Height 67 in, waist 34 in
- BRI = 3.5
- Below the 4.5–5.5 band where risk was lowest in the study
Things to keep in mind
- A screening estimate, not a diagnosis; discuss results with a doctor.
Questions people ask
What units?
Any, as long as height and waist use the same one.
Does it replace BMI?
It adds information about fat distribution; doctors may use both.