The Body Roundness Index (BRI) Calculator scores your body shape from waist and height on a 1–20 scale. BRI predicts visceral fat and cardiovascular risk better than BMI because it directly captures abdominal obesity — the fat pattern most strongly linked to metabolic syndrome and heart disease.
3.09
0.988
24.5
kg/m²
0.486
-2.5
cm
48.6
%
3.09
0.988
24.5
kg/m²
0.486
-2.5
cm
48.6
%
Your waist circumference relative to your height tells you more about cardiovascular risk than your weight relative to your height does. The Body Roundness Index formalizes this: it uses the ratio of waist circumference to height to produce a single score that captures how much abdominal fat you carry — the specific fat depot most strongly associated with insulin resistance, metabolic syndrome, and cardiovascular disease. The BRI calculator gives you this score and places it in context of population health risk data.
BRI = 364.2 − 365.5 × √(1 − (waist/2π × height)²)
where waist and height are in the same units (both meters or both inches). The formula is derived from the elliptical area of a human cross-section — literally measuring how elliptical (elongated) vs. circular (round) your body shape is.
Example: waist 85 cm, height 170 cm: BRI = 364.2 − 365.5 × √(1 − (0.085/2π × 1.70)²) ≈ 4.8. Use this online calculator for your BRI. The waist-to-hip ratio calculator and BRI together provide a comprehensive abdominal fat assessment.
Multiple large cohort studies have shown BRI predicts cardiovascular disease, metabolic syndrome, and all-cause mortality better than BMI. A 2023 study of over 33,000 US adults (NHANES) found BRI was significantly better than BMI at predicting cardiovascular disease risk (AUC 0.71 vs. 0.63). The reason: abdominal (visceral) fat is metabolically active — it secretes inflammatory cytokines, promotes insulin resistance, elevates triglycerides, and reduces HDL — all direct drivers of cardiovascular disease. BMI measures total weight; BRI measures specifically the abdominal distribution that drives metabolic harm. The BMI calculator and body composition calculators complement BRI for a complete assessment.
BRI is mathematically derived from waist-to-height ratio (WHtR). A simple, widely validated rule: your waist should be less than half your height (WHtR below 0.5). This "keep your waist less than half your height" rule works across ethnicities and sexes. A 170 cm tall person should aim for waist circumference below 85 cm. A 180 cm person: below 90 cm. This simple guideline captures most of the health information in BRI and is easier to remember and apply.
BRI below 3.41 indicates low cardiometabolic risk (lean body shape). 3.41-4.45 is below average risk. 4.45-5.46 is average. 5.46-6.91 is above average risk. Above 6.91 indicates high risk with significant central adiposity. Compare with your BMI: if BRI suggests high risk but BMI is normal, you may have hidden visceral fat requiring attention.
Inputs
Results
BRI 2.84 with high eccentricity (0.99) indicates a lean, elongated body shape with low cardiometabolic risk.
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Results
BRI 6.78 indicates above average cardiometabolic risk due to significant central adiposity. BMI confirms obesity classification.
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