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A Body Shape Index (ABSI) Calculator

Enter waist circumference (m), BMI and height (m) to get your ABSI.

How it is calculated

The tool applies ABSI = WC / (BMI^(2/3) × height^(1/2)). WC is waist circumference and height is body height, both in metres (85 cm is entered as 0.85). BMI is the usual kg/m² value and you enter it yourself; the tool does not calculate it from weight. All three numbers must be above zero. The result is shown with five decimals and has no unit. It returns only the raw index. It does not convert it to a z-score, compare it with age and sex reference values or label a risk category, so it cannot say by itself whether a value is high or low for you. Interpretation needs published reference data for your age and sex.

Worked example

Waist 0.85 m, BMI 24.5, height 1.75 m. BMI^(2/3) = 24.5^0.6667 ≈ 8.436. Height^(1/2) = √1.75 ≈ 1.3229. Denominator = 8.436 × 1.3229 ≈ 11.160. ABSI = 0.85 ÷ 11.160 = 0.07617. Two people with the same BMI and height can differ here only through waist size: a larger waist raises the index in direct proportion.

Try this example →

Common mistakes

  • Entering waist and height in centimetres. The formula expects metres: 85 and 175 give 0.76171 instead of 0.07617.
  • Entering waist in inches. Convert to metres first (inches × 0.0254).
  • Leaving BMI as a number from a different formula or an old measurement. Use your current BMI in kg/m².
  • Reading 0.07617 as a percentage or a risk score. It is an index that only means something when compared with reference values for your age and sex.
  • Replacing BMI or waist-to-hip ratio with it. ABSI is an add-on measure and says nothing about muscle or bone mass.

Sources

About this calculator

A Body Shape Index (ABSI) was developed to address a known weakness of BMI: BMI alone can't distinguish someone with a lot of abdominal fat from someone with the same weight but a slimmer waist. ABSI corrects for this using the formula ABSI = WC ⁄ (BMI^(2/3) · height^(1/2)), where WC is waist circumference in meters, effectively normalizing waist size against what would be statistically expected for a given BMI and height.

Because abdominal (visceral) fat carries a stronger link to cardiovascular and metabolic risk than overall body mass, epidemiological studies have found ABSI correlates with mortality risk independently of BMI — a high-ABSI person can appear to have a “normal” BMI while still carrying elevated central adiposity risk. Researchers and health-risk assessment tools use it as a complementary measure alongside, not a replacement for, BMI and waist-to-hip ratio.

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