How is ABSI calculated?

ABSI equals waist circumference divided by BMI to the power of two-thirds times the square root of height, with waist and height in metres. For a 90 cm waist, 175 cm height and 80 kg weight, BMI is 26.1, BMI to the two-thirds power is about 8.80, the square root of 1.75 m is about 1.32, so ABSI is 0.90 divided by 11.65, which is about 0.0773.

What is a good ABSI score?

Adult values cluster around 0.08. A lower score means your waist is smaller than your height and weight would predict, and large population studies have linked lower ABSI with lower premature mortality risk, while higher scores point to more central fat. ABSI is a screening number only, so discuss unusual results with your doctor rather than reading it as a diagnosis.

How is ABSI different from BMI?

BMI only uses height and weight, so it cannot tell fat from muscle or say where fat sits on the body. ABSI adds waist circumference and adjusts it for the waist your BMI and height would predict, so it specifically flags weight carried around the middle. Two people with identical BMIs can have quite different ABSI scores if one has a larger waist.

ABSI Calculator

This ABSI calculator works out your A Body Shape Index from three tape-and-scale measurements: waist circumference, height and weight. BMI on its own treats every body as the same shape, so two people with the same height and weight score identically even when one carries most of their weight around the middle. ABSI was designed to fix that blind spot: it takes your waist measurement and adjusts it for the waist size your BMI and height would predict, which isolates central fat, the kind stored around the organs that research links most strongly to health risk. Enter your measurements and the calculator returns your ABSI along with your BMI, your BMI category and your waist-to-height ratio, so you can see the common screening numbers side by side. Most adults land around 0.08: a higher figure means a larger waist than expected for your build, and a lower figure means a smaller one. Measure your waist level with your navel after breathing out normally, without pulling the tape tight, and measure your height without shoes. Like every screening index, ABSI is a starting point for a conversation with your doctor rather than a diagnosis, so treat the result as information, not a verdict.

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Waist circumference

Height

Weight

0.0773

your A Body Shape Index (ABSI)

BMI26.1

BMI categoryOverweight

Waist-to-height ratio0.51

Your ABSI of 0.0773 sits below the typical adult value of about 0.08: your waist is smaller than expected for your height and weight, a pattern studies link with lower central-fat risk.

Measure your waist level with the navel after a normal breath out, with the tape snug but not tight. ABSI is a screening measure only and does not account for age, sex or ethnicity; it is not medical advice.

How it works

ABSI, published by Krakauer and Krakauer in 2012, is waist circumference divided by BMI to the power of two-thirds times the square root of height, with waist and height in metres and BMI in kg/m². The exponents were chosen so that, across a large population sample, the index is roughly independent of height, weight and BMI, meaning it captures the part of your waist measurement that those numbers cannot explain. The calculator first computes BMI as weight divided by height squared, then applies the ABSI formula, and also reports your waist-to-height ratio, a simpler central-fat screen. Because the formula raises BMI to a fractional power, ABSI values are small numbers clustered near 0.08 for adults, and small differences matter: moving from 0.078 to 0.083 represents a clearly larger waist for the same build.

Worked example

With a 90 cm waist, 175 cm height and 80 kg weight: BMI = 80 / 1.75² = 26.1, which sits in the overweight category. BMI to the power of two-thirds is about 8.80, and the square root of 1.75 m is about 1.32, so the denominator is about 11.65. ABSI = 0.90 / 11.65 = 0.0773. The waist-to-height ratio is 90 / 175 = 0.51. An ABSI of 0.0773 is below the typical adult value of about 0.08, meaning this waist is a little smaller than the height and weight would predict, even though the BMI alone reads as overweight. That contrast is exactly the gap ABSI was built to expose.

Related calculators

BMI Calculator: body mass index from height and weight.
Waist to Hip Ratio Calculator: another central-fat screen.
Body Fat Percentage Calculator: estimate body fat.
Ideal Weight Calculator: healthy weight ranges.
Body Shape Calculator: hourglass, pear, apple or rectangle.

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