A Body Shape Index
Calculate A Body Shape Index (ABSI) for mortality risk assessment. Input waist, height, weight, age, and sex for ABSI z-score with risk classification.
About This Calculator
What is A Body Shape Index (ABSI)?
A Body Shape Index (ABSI) is a medical index developed by Nir Krakauer and Jesse Krakauer that estimates the risk of premature mortality based on waist circumference relative to height and weight. Unlike BMI, which only considers height and weight, ABSI specifically accounts for abdominal fat distribution — a key risk factor for cardiovascular disease, type 2 diabetes, and certain cancers.
The ABSI formula is: ABSI = WC / (BMI2/3 × height1/2), where WC is waist circumference in meters, BMI is body mass index in kg/m², and height is in meters. The resulting ABSI score is then converted to a z-score using age- and sex-specific reference values from the NHANES (National Health and Nutrition Examination Survey) study. The z-score indicates how many standard deviations your ABSI is from the population mean for your demographic group.
How to Use This Calculator
Select your biological sex, enter your age (18–85), height in centimeters, weight in kilograms, and waist circumference measured at the level of the navel. The calculator will compute your ABSI score, z-score, BMI, and mortality risk classification ranging from Very Low to Very High. Use the chart tabs to visualize either your raw ABSI score or your z-score on a bar chart for easy comparison.
Regional Notes
India: The NHANES reference data used for z-score calculation is based on the US population. For Indian adults, the age- and sex-specific ABSI norms may differ slightly due to differences in body composition. Indian adults tend to have higher body fat at lower BMIs, so consult a physician for personalized interpretation. The International Diabetes Federation recommends waist circumference thresholds of ≥90 cm for Indian men and ≥80 cm for Indian women as indicators of central obesity.
United States: NHANES data is derived from the US adult population, making it most applicable to US users. ABSI has been validated in multiple US cohort studies including the National Health Interview Survey. The US Preventive Services Task Force recommends screening for obesity (BMI ≥30 kg/m²) but does not currently include ABSI in standard guidelines.
United Kingdom: The UK National Institute for Health and Care Excellence (NICE) recommends using BMI with waist circumference to assess health risk. ABSI is not part of standard NHS guidelines but offers complementary risk information. UK Biobank data has been used to validate ABSI as a mortality predictor in UK populations.
Frequently Asked Questions
What is A Body Shape Index (ABSI)?
A Body Shape Index (ABSI) is a medical index developed by Krakauer and Krakauer that estimates the risk of premature mortality based on waist circumference relative to height and weight. It is considered a better indicator of mortality risk than BMI alone because it accounts for abdominal fat distribution.
How is ABSI calculated?
ABSI is calculated using the formula: ABSI = WC / (BMI^(2/3) × height^(1/2)), where WC is waist circumference in meters, BMI is body mass index in kg/m², and height is in meters. The z-score (standard deviation score) is then computed based on age- and sex-specific NHANES reference data.
What does a high ABSI z-score mean?
A higher ABSI z-score indicates a greater proportion of abdominal fat relative to overall body size, which is associated with increased risk of premature mortality, cardiovascular disease, type 2 diabetes, and certain cancers. A z-score above 0.229 indicates high risk, and above 0.798 indicates very high risk.
How is ABSI different from BMI?
While BMI only considers height and weight, ABSI incorporates waist circumference to measure abdominal fat distribution. This makes ABSI a more precise predictor of mortality risk since central obesity is a stronger risk factor than overall body mass. ABSI correlates only weakly with BMI, providing independent risk information.
What are the ABSI risk level thresholds?
Based on the NHANES reference population, ABSI z-score thresholds are: below -0.868 (very low risk), -0.868 to -0.272 (low risk), -0.272 to +0.229 (average risk), +0.229 to 0.798 (high risk), and above 0.798 (very high risk). These thresholds apply to both men and women.
Can I use this calculator if I am under 18?
The ABSI calculator is validated for adults aged 18 to 85 based on NHANES reference data. For children and adolescents under 18, the reference values may not apply. Consult a pediatrician or healthcare professional for age-appropriate body composition assessment.
Is ABSI used in clinical practice?
ABSI is primarily a research tool that complements traditional measures like BMI and waist circumference. It is gaining recognition in epidemiological studies but is not yet a standard clinical guideline metric. In India, the US, and the UK, healthcare professionals typically use BMI, waist circumference, and waist-to-hip ratio for routine assessment.
Can I rely on ABSI results for medical decisions?
No. This calculator is for educational and reference purposes only. ABSI results should not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for a comprehensive health assessment that considers your full medical history and risk factors.