Body Roundness Index Calculator
Calculate your Body Roundness Index (BRI) from height and waist circumference, a shape-based measure of central fat. Example: a 70 in height with a 34 in waist gives a BRI of about 3.1.
Show steps
How to use the Body Roundness Index Calculator
- Enter the values in the fields.
- Press Calculate to see the result with the steps shown.
Formula and method
BRI = 364.2 – 365.5 x sqrt(1 – ((waist circumference / 2 pi)^2 / (0.5 x height)^2)), with waist and height in the same units.
BRI ranges (approximate)
| BRI | Reading |
|---|---|
| Below 3.4 | Lean |
| 3.4 to 4.4 | Healthy |
| 4.5 to 5.4 | Above average |
| 5.5 to 6.8 | High |
| 6.9 and above | Very high |
BRI for sample builds
| Height | Waist | BRI |
|---|---|---|
| 5 ft 4 in | 28 in | 2.4 |
| 5 ft 8 in | 32 in | 3.1 |
| 5 ft 10 in | 34 in | 3.7 |
| 6 ft 0 in | 38 in | 4.8 |
| 5 ft 6 in | 42 in | 7.7 |
BRI versus BMI
BMI cannot tell fat from muscle or where fat sits. BRI uses the waist, so it tracks abdominal fat, which carries most of the metabolic risk.
Cautions
This calculator is for education and is not medical advice. Decisions about testing and treatment belong with a qualified clinician.
Studies find mortality risk is lowest in a mid-range and rises at both very low and very high BRI; the bands here are commonly cited approximations.
Frequently asked questions
What is Body Roundness Index?
A shape index from height and waist circumference.
What is a healthy BRI?
Roughly 3.4 to 4.4.
Who developed BRI?
Thomas et al., 2013.
Is BRI better than BMI?
It reflects visceral fat better, but both are screening tools.
How do I measure my waist?
At the navel, after a normal exhale.
Does BRI work for athletes?
Reasonably, as it does not use weight.
Sources
- Thomas et al., Obesity 2013: Body Roundness Index
- Zhang et al., JAMA Network Open 2024: BRI and mortality
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