ABSI Calculator
The ABSI (A Body Shape Index) calculator scores how much your waist size stands out for your height and weight, then compares it to population norms by sex to give a z-score and risk band. Enter your sex, age, weight, height and waist circumference. Because it adjusts for BMI and height, ABSI captures central-fat risk that BMI alone misses.
Rates and fees change frequently. Always confirm the current figures
with the official authority before relying on this result.
- Z-score population parameters are approximate averages from published research.
- Valid for adults aged 18–80 only.
- Does not account for age-specific population norms.
Formula
ABSI = WC(m) / (BMI^(2/3) × height(m)^0.5)
- ABSI = waist (m) ÷ (BMI^(2/3) × height (m)^0.5), where BMI comes from your weight and height.
- The result is converted to a z-score using sex-specific population means and standard deviations from Krakauer & Krakauer (2012).
- A positive z-score means a higher ABSI than average for your sex — more central fat and higher risk.
- Risk bands run from very low to very high based on how many standard deviations you sit from the mean.
- ABSI adds information beyond BMI and waist alone, but it remains a screening estimate, not a diagnosis.
Example Calculation
Inputs
- Age: 30 years
- Weight: 70 kg
- Height: 170 cm
- Waist Circumference: 80 cm
For a 30-year-old man, 70 kg, 170 cm tall with an 80 cm waist, BMI is about 24.2 and ABSI ≈ 0.0733. Against the male mean (0.0830, SD 0.0055) that is a z-score of about −1.8, a very-low-risk result.
Frequently asked questions
What does ABSI measure?
It measures how large your waist is relative to your BMI and height, capturing central (abdominal) fat that BMI on its own cannot show.
What is the z-score for?
It compares your ABSI to the average for your sex. A positive z-score is above average (higher risk); a negative one is below average (lower risk).
Why does sex matter?
Men and women have different average ABSI values, so the calculator uses sex-specific means and standard deviations to set the risk band fairly.
Can I have a normal BMI but high ABSI?
Yes. That is the point of ABSI — someone of healthy weight can still carry excess fat around the middle and show elevated risk.
Is ABSI a medical diagnosis?
No. It is a research-based screening estimate. Use it alongside other measures and professional advice, not as a standalone diagnosis.
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