Body Roundness Index (BRI) Calculator
Estimate abdominal roundness and visceral fat risk using waist circumference and height. BRI complements BMI by focusing on central adiposity.
Your Measurements
Measure waist at the navel (men) or narrowest waist (women). Stand upright with relaxed breathing.
BRI Results
Body Roundness Index
-0.14
Waist-to-height ratio
0.50
Measurements (cm)
Waist: 85.0 cm • Height: 170.0 cm
Interpretation
Very low roundness. Usually associated with low abdominal adiposity.
How to Use This Calculator
Measure accurately
Wrap a measuring tape around the waist at the level of the navel or natural waist. Keep the tape horizontal and snug but not tight.
Enter waist and height
Use the same unit system for both inputs. The calculator converts to centimeters before computing BRI.
Review BRI and ratio
Compare your Body Roundness Index and waist-to-height ratio to the interpretation panel for actionable insights.
Formula
BRI = 364.2 − 365.5 × √{1 − (waist / (2π × height))²}
- Waist and height must be in meters before applying the formula.
- The term inside the square root reflects the ratio of waist circumference to height.
- BRI approximates body shape from a cylindrical model to estimate visceral fat.
Example: waist = 0.85 m, height = 1.70 m → BRI ≈ 364.2 − 365.5 × √(1 − (0.85 / (2π × 1.70))²) ≈ 3.10.
Why Body Roundness Index Matters
BRI focuses on abdominal roundness, a marker closely linked to metabolic syndrome and cardiovascular risk. Unlike BMI, it can differentiate people with the same weight but different waist sizes.
Use BRI alongside traditional measures such as BMI, waist circumference, and blood markers. Lifestyle changes that reduce waist-to-height ratio often lower BRI and associated health risks.
Frequently Asked Questions
Is BRI a replacement for BMI?
No. BMI estimates total body mass relative to height, while BRI targets abdominal shape. Using both offers a fuller picture.
What is a healthy BRI score?
Scores around 1.5–3.0 are generally considered within a healthy range. Higher values suggest increased abdominal adiposity.
Can I lower my BRI?
Yes. Lifestyle adjustments—balanced nutrition, activity, stress management—help reduce waist circumference relative to height.
Does BRI work for athletes?
Athletes with low waist circumference typically show low BRI even at higher body weights, making it useful for tracking central fat.