Body Shape Index Calculators
Two newer metrics that go beyond weight and BMI by modeling how your weight is distributed.
What this category covers
BMI is a useful population-level screen but a poor individual one — it does not distinguish between muscle and fat, and it ignores where you carry your weight. The two tools in this category were built to fix that:
- Body Roundness Index (BRI) — models your body as an ellipse using waist and height. A 2024 JAMA Network Open study of 32,995 US adults showed BRI follows a U-shaped mortality curve, with the lowest risk around 4.5–5.5.
- Waist-to-Height Ratio (WHtR) — the simple "waist less than half your height" rule. Universal threshold of 0.5 across all ages and sexes. Supported by a 2012 meta-analysis of 200,000+ adults.
All body shape index tools
Why "shape" matters more than weight
Visceral fat — the fat stored around your organs inside the abdomen — is metabolically active in ways that subcutaneous fat is not. Two people with the same BMI can have very different visceral-fat loads and therefore very different cardiometabolic risk. Body shape metrics that incorporate waist circumference capture this distinction; BMI does not.
For a deep read, see our Body Shape Indices guide.