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BRI

General

Body Roundness Index

A body shape metric using waist circumference and height to estimate body roundness as a proxy for fat distribution, addressing a key limitation of BMI.

Definition

Body Roundness Index (BRI) estimates a person's body roundness โ€” a proxy for central fat distribution โ€” using waist circumference and height, modelling the body's cross-section as an ellipse. It was developed to address a specific limitation of BMI: BMI cannot distinguish between two people of identical height and weight who carry fat differently, while BRI captures this by incorporating waist circumference directly.

The BRI Calculator performs this calculation from your waist circumference and height.

Formula

BRI = 364.2 โˆ’ 365.5 ร— โˆš(1 โˆ’ [Waist Circumference รท (2ฯ€)]ยฒ รท (0.5 ร— Height)ยฒ)

Waist circumference and height must be in the same units (commonly centimetres).

Worked Example

For a waist circumference of 90 cm and height of 170 cm:

  • Waist รท (2ฯ€) = 90 รท 6.2832 โ‰ˆ 14.32
  • 0.5 ร— Height = 85
  • (14.32 รท 85)ยฒ โ‰ˆ 0.0284
  • 1 โˆ’ 0.0284 = 0.9716
  • โˆš0.9716 โ‰ˆ 0.9857
  • BRI = 364.2 โˆ’ 365.5 ร— 0.9857 โ‰ˆ 3.93

BRI values typically range from about 1 to 10, with lower values indicating a leaner body shape.

Key Things to Know

  • No weight measurement required: unlike BMI, BRI is calculated from waist circumference and height alone.
  • Captures fat distribution, not just size: two people with the same BMI can have meaningfully different BRI scores.
  • Complementary to BMI, not a replacement: most guidance treats BRI as an additional data point rather than a full substitute for BMI.
  • Simpler alternative available: the Waist-to-Height Ratio Calculator uses the same two measurements with a much simpler ratio formula.

Related Calculators

BRI Calculator โ†’Calculate your Body Roundness Index (BRI) from waist circumference and height to estimate visceral fat and body shape-related health risk.
BMI Calculator โ†’Calculate your BMI instantly using kg/lbs and cm/ft. Includes BMI category and healthy weight range using WHO standards.
Waist to Height Ratio Calculator โ†’Calculate your waist-to-height ratio, a strong predictor of cardiovascular and metabolic health risk, and see your result compared to the 0.5 threshold.

Related Terms

BMIBody Mass IndexWHRWaist-to-Hip Ratio

Frequently Asked Questions

BRI was developed specifically to address BMI's inability to distinguish fat distribution or body shape, since BMI treats two people of the same height and weight identically even if one carries fat centrally around the abdomen and the other doesn't.
Just your waist circumference and height โ€” no weight measurement is needed, which is one practical difference from BMI. The [BRI Calculator](/bri-calculator/) uses these two inputs.
Research suggests BRI may correlate more closely with visceral fat and related health risks than BMI in some studies, but both are screening tools, not diagnostic measures โ€” neither should be used alone to determine health status.
Yes โ€” this is exactly the scenario BRI is designed to catch, since two people with identical height and weight can have very different waist circumferences and body shapes, producing different BRI results.
BRI is newer and less universally adopted in standard clinical practice than [BMI](/glossary/bmi/), which remains the default screening tool in most medical guidelines, though BRI is gaining research attention as a complementary measure.