By Zencalcy Editorial TeamLast reviewed About us
A Body Shape Index (ABSI) combines waist circumference with height and body mass index to describe how much abdominal fat a person carries relative to their overall size. It was proposed as a complement to BMI, which cannot tell muscle from fat or show where fat sits. A higher ABSI means a larger waist for the same height and BMI.
Score abdominal adiposity relative to height and BMI.
ABSI = waist(m) ÷ [BMI^(2/3) × height(m)^(1/2)] BMI = weight(kg) ÷ height(m)²
Waist and height must use the same unit system before conversion to metres. The original ABSI work by Krakauer and Krakauer (2012) found that a larger waist relative to height and BMI was associated with higher mortality risk, but risk thresholds vary by age, sex and population, so this tool reports the index rather than inventing a category.
| Symbol | Meaning |
|---|---|
| ABSI | A Body Shape Index, typically around 0.07–0.10 in adults. |
| waist | Waist circumference in metres. |
| BMI | Body mass index in kg/m². |
| height | Standing height in metres. |
BMI is 70 ÷ 1.75² = 22.9. BMI^(2/3) is about 8.06 and the square root of 1.75 is 1.323, so ABSI = 0.85 ÷ (8.06 × 1.323) = 0.080. Repeating the measurement after a few weeks shows whether abdominal fat is changing even when weight is stable.
Two people with the same BMI can carry fat very differently. Fat stored around the abdominal organs, called visceral fat, is more strongly linked to insulin resistance, dyslipidaemia and cardiovascular events than fat stored under the skin on the hips and thighs. BMI cannot distinguish these patterns, which is why waist-based indices became popular in epidemiology. ABSI goes a step further than raw waist circumference by scaling waist to both height and BMI, so a tall, heavy person is not automatically penalised. The index is modestly correlated with BMI, meaning it carries information the scale does not. For personal tracking, take the measurement at the same landmark, at the same time of day, and compare monthly averages rather than single readings.
Continue with the Adjusted Body Weight Calculator, BAI Calculator (Body Adiposity Index), or the Body Frame Size Calculator — or browse more body measurements tools and all health calculators.
Also see the Body Fat Calculator.
Neither replaces the other. BMI reflects overall mass, while ABSI adds waist distribution. ABSI has been associated with mortality risk independent of BMI in large cohorts, but it is a research index rather than a clinical diagnosis.
Every result is a screening estimate from published anthropometric equations, not a diagnosis or a measurement of body composition. Tape measurements should be taken snugly against the skin without compressing it, at the landmarks named in each tool. Equations were derived in specific populations and can be less accurate for athletes, older adults, children, pregnant people and people with significant oedema.
Reference material used to build and check this calculator:
Last reviewed: September 2026. See how we build and check every tool on the about page.
Content updated: September 2026