ABSI Calculator (A Body Shape Index)

ABSI is a health metric developed by Nir and Jesse Krakauer based on data from the US National Health and Nutrition Examination Survey. It estimates premature mortality risk using waist circumference, height, and weight. Unlike BMI, ABSI specifically factors in where fat is distributed on the body, making abdominal fat — the most dangerous type — a key part of the assessment.

The ABSI formula is: ABSI = WC / (BMI^(2/3) × height^(1/2)), where WC is waist circumference in metres, BMI is body mass index (kg/m²), and height is in metres. A higher ABSI value indicates more abdominal fat relative to your overall body size, which is associated with greater mortality risk.

The ABSI z-score normalises your raw ABSI value against population averages for your age and sex. It is calculated as: z = (ABSI − mean_ABSI) / SD_ABSI, using reference mean and standard deviation values derived from population studies. A z-score of 0 is average, negative scores are below average risk, and positive scores indicate above-average risk.

A higher ABSI z-score means your waist circumference is large relative to your height and weight, indicating a greater concentration of abdominal (visceral) fat. This is linked to increased risk of cardiovascular disease, type 2 diabetes, and premature mortality. An ABSI z-score above +0.5 places you in the above-average to high risk category.

Yes. Because ABSI captures abdominal fat distribution, it correlates with insulin resistance and metabolic syndrome — key precursors to type 2 diabetes. Research has shown ABSI can be a useful complementary indicator alongside fasting glucose and other metabolic markers, though it should not replace clinical testing.

An ABSI z-score above 1 places you in the 'high' mortality risk category, meaning your body shape carries significantly more risk than average for your age and sex. This is largely driven by excess visceral (abdominal) fat. Lifestyle changes such as reducing caloric intake, increasing aerobic exercise, and consulting a healthcare provider are strongly recommended.

ABSI has advantages over BMI because it specifically accounts for waist circumference, which reflects visceral fat — a stronger predictor of cardiometabolic risk than overall body weight. However, ABSI is not perfect; it can underestimate risk in very lean or very muscular individuals. Using both ABSI and BMI together gives a more complete picture of health.

Pros: ABSI incorporates waist size, is independent of height and weight, and is a better predictor of mortality risk than BMI alone. Cons: It requires an accurate waist measurement (which many people take incorrectly), it does not directly measure body fat percentage, and it is less well-known than BMI so reference ranges are less standardised. Always use it as one tool among several health indicators.