Last updated October 10, 2026 · Report an error
The Body Roundness Index (BRI), from Thomas et al. (2013), models the body as an ellipse using waist circumference and height to estimate "roundness" as a proxy for visceral fat. This calculator is for general reference and educational purposes only — it is not a medical diagnosis. Consult a doctor or qualified professional for an actual body composition assessment.
How it works
Enter your waist circumference and height (same units). The tool applies the published BRI geometric formula, which models eccentricity of an ellipse fitted to your waist and height.
- Enter waist circumference (cm).
- Enter height (cm).
- Click Calculate to see your results.
Examples
A 90cm waist at 175cm height
BRI ≈ 3.5, within the range research associates with lower cardiometabolic risk.
Who should use it
- Exploring a research-grade body-shape metric.
- Tracking waist-adjusted body roundness over time.
Industry applications
- Public health and epidemiology research
- General wellness tracking
Advantages
- Uses a geometric model validated against visceral fat measurements in the original research.
- Requires only two simple measurements.
Limitations
- Less familiar than BMI, with no single officially adopted clinical cutoff.
- Primarily a research metric rather than an individual diagnostic tool.
Common mistakes to avoid
- Treating a single BRI value as a diagnosis rather than a research-context reference number.
- Measuring waist circumference inconsistently between checks.
Best practices
- Use BRI alongside other measures like waist-to-height ratio, not in isolation.
Tips
- Measure waist circumference at the navel, standing relaxed, for a consistent reading.
Frequently asked questions
Yes, with no signup and no limit on how many calculations you run.
Published research associates higher BRI values with greater visceral-fat-related risk, and lower values with lower relative risk — but this calculator provides the reference number only, not a diagnosis.
Thomas DM et al., "Relationships between body roundness with body fat and visceral adipose tissue emerging from a new geometrical model", Obesity (Silver Spring), 2013.