What is a good Body Roundness Index (BRI) score?
Get your BRI score and see how you compare to US adults and the 2024 JAMA mortality curve.
Bars: same-sex adults 18-85. Dashed line: relative all-cause mortality (Zhang et al., JAMA 2024).
What the Research Says About BRI
Body Roundness Index has rapidly gained attention since the landmark JAMA Network Open study published in 2024 by Zhang et al., which analyzed 32,995 US adults from NHANES 1999–2018. The study found that BRI follows a U-shaped association with all-cause mortality — meaning both very low and very high BRI values carry increased risk, with the lowest mortality observed at a BRI of approximately 4.5–5.5.
Key findings from recent research:
- Superior to BMI: The JAMA 2024 study demonstrated that BRI consistently outperformed BMI in predicting all-cause mortality across all age groups, genders, and ethnicities. This is because BRI captures where fat is distributed (central vs. peripheral), while BMI only measures total mass.
- Cardiometabolic risk: A 2023 study in Frontiers in Endocrinology found BRI to be strongly correlated with hypertension, diabetes, and metabolic syndrome — even in individuals with normal BMI. Higher BRI was associated with a 2- to 3-fold increase in cardiometabolic risk.
- Trend over time: Analysis of NHANES data shows that average BRI in US adults has increased significantly from 1999 to 2018, mirroring the rise in central obesity. This trend was most pronounced in younger adults and certain ethnic groups, highlighting the growing importance of body shape metrics in public health.
- Comparison with other metrics: While waist circumference is a simpler measure, BRI normalizes waist size to height — making it comparable across people of different body sizes. A tall person with a 90 cm waist has a different body shape than a short person with the same waist measurement; BRI captures this difference.
The BRI formula was originally developed by Thomas et al. (2013) in Diabetes Technology & Therapeutics. It models the body as a 2D ellipse using waist circumference and height — lower values indicate an elongated (thinner) body shape, while higher values indicate a rounder shape. The growing body of evidence since 2013 supports BRI as a valuable addition to clinical assessment, especially for individuals whose BMI falls in the "normal" range but who carry excess abdominal fat.
How to Measure
- Height: Measure without shoes, stand straight against a wall
- Waist: Measure at the level of your iliac crest (hip bone)
- Use a flexible, non-stretchable tape measure
- Measure at the end of a normal exhale
Frequently asked questions
Quick answers to common questions
What is Body Roundness Index (BRI)?
Body Roundness Index is a newer body shape metric that quantifies the degree of central obesity by modeling the body as an ellipse. It was introduced by Thomas et al. in 2013 and validated in JAMA 2024 as a strong predictor of mortality — outperforming BMI.
What is a normal Body Roundness Index?
BRI values typically range from about 1 to 16. A BRI below 5 indicates lower health risk (more elongated body shape), 5–7 is moderate risk, and above 7 is high risk (rounder body shape). The US average for adults is around 5–7 depending on age and gender.
How does BRI differ from BMI?
BMI only uses height and weight, so two people with the same BMI can have very different body shapes. BRI uses height and waist circumference, capturing where fat is distributed — which is more strongly linked to health outcomes.
Is BRI better than waist circumference?
Both are useful. Waist circumference gives an absolute measurement, while BRI normalizes waist to height — making it comparable across different body sizes. BRI also better predicts mortality than either BMI or waist circumference alone (JAMA 2024).
What is the BRI formula?
BRI = 364.2 − 365.5 × √(1 − (WC/2π)² / (0.5 × H)²), where WC is waist circumference and H is height. The formula models the body as an ellipse, with the ratio of waist to height determining roundness.
Can BRI be used for children?
The BRI was originally developed for adults. While the formula can be applied to children, the risk thresholds (<5, 5-7, >7) are validated in adult populations. Pediatric BRI norms differ by age and developmental stage.
References
Peer-reviewed sources behind this calculator
- Zhang X, et al. (2024). JAMA Network Open. Body Roundness Index and All-Cause Mortality Among US Adults. doi:10.1001/jamanetworkopen.2024.15052
- Thomas DM, et al. (2013). Diabetes Technology & Therapeutics. A new body shape index predicts mortality hazard independently of body mass index. doi:10.1089/dia.2012.0331
- Rico-Martín S, et al. (2023). Frontiers in Endocrinology. Body Roundness Index and cardiometabolic risk: a systematic review and meta-analysis. doi:10.3389/fendo.2023.1142636
Show all 4 references
- Centers for Disease Control and Prevention (2021). NHANES 2011-2018. Body Measures (BMX) Data Documentation.
Methodology
BRI formula: Thomas et al. (2013), Diabetes Technology & Therapeutics. DOI: 10.1089/dia.2012.0331
Risk thresholds: JAMA Network Open (2024), DOI: 10.1001/jamanetworkopen.2024.15052
Reference percentile data: NHANES 2011-2023 (n=28,000+)
Disclaimer: For informational purposes only. Not medical advice.
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