Need a simple way to estimate body shape using waist size, height, and weight? An A Body Shape Index (ABSI) Calculator calculates your body shape index using waist circumference, height, and weight. It helps assess how your waist size compares with what would be expected for your overall body size, offering information that Body Mass Index (BMI) alone cannot provide.
ABSI was introduced in a 2012 study by Nir Y. Krakauer and Jesse C. Krakauer to examine the relationship between body shape and mortality risk. Your result is a screening measure, not a diagnosis or a direct prediction of your personal health outcome. This guide explains the ABSI formula, calculation steps, result interpretation, and limitations.
Key Takeaways
- ABSI uses waist circumference, height, and weight to assess body shape relative to overall body size.
- The ABSI formula uses BMI, waist circumference in metres, and height in metres.
- A raw ABSI value alone does not establish an individual's health risk. Age- and sex-adjusted reference data can help interpret the result.
- ABSI complements BMI by accounting for waist size, which BMI does not measure directly.
- ABSI is a screening measure and should not replace a medical assessment.
What Is an A Body Shape Index (ABSI) Calculator?
An A Body Shape Index (ABSI) Calculator measures waist circumference relative to height and Body Mass Index. Researchers developed ABSI to examine whether waist size provides information about body shape and mortality risk beyond BMI alone.
BMI describes weight relative to height, but it does not directly measure abdominal fat. ABSI adds waist circumference to the calculation and adjusts it for BMI and height.
The resulting index is a small numerical value, not a percentage. To interpret it in relation to population health risks, you may need an ABSI z-score based on appropriate age- and sex-specific reference data.
What information do you need?
The standard ABSI calculation uses three measurements or values:
- Waist circumference: The distance around your abdomen, measured consistently using a tape measure.
- Height: Your standing height, expressed in metres for the standard formula.
- Weight: Your body weight, expressed in kilograms when calculating BMI.
Age and sex are not required to calculate the raw ABSI value. They are relevant when comparing that value with age- and sex-specific population reference values.
How to Calculate ABSI: The Formula
The ABSI formula divides waist circumference by BMI raised to the power of two-thirds, multiplied by the square root of height. The standard formula uses waist circumference and height in metres and BMI in kilograms per square metre.
Formula
Where:
- ABSI = A Body Shape Index.
- WC = Waist circumference in metres.
- BMI = Body Mass Index in kilograms per square metre.
- H = Height in metres.
BMI is calculated using weight and height.
BMI formula
Where:
- W = Weight in kilograms.
- H = Height in metres.
Both formulas must use consistent units. Convert centimetres to metres before substituting height or waist circumference into the equations.
Why does the ABSI formula use BMI and height?
The formula adjusts waist circumference for overall body size. This helps researchers examine whether a person's waist is relatively large or small compared with what the person's height and BMI would suggest.
The fractional exponents come from the statistical model used to develop ABSI. They are part of the original formula and should not be changed when calculating the standard index.
How to Use the ABSI Calculator
You can calculate ABSI by entering your measurements into the calculator and using the formula above.
- Enter your waist circumference. Measure your waist carefully and select the correct unit.
- Enter your height. Use your measured height, selecting centimetres, metres, feet, or inches as supported by the calculator.
- Enter your weight. Select kilograms or pounds, depending on the calculator's available options.
- Calculate your ABSI. The calculator converts the measurements into the units required by the formula, calculates BMI, and then calculates ABSI.
- Review the result. Check whether the displayed result is a raw ABSI value, a standardized z-score, or a statistical risk estimate. These are different outputs.
If the calculator provides a z-score or relative-risk estimate, check which reference population and statistical model it uses. Different reference data or methods can produce different interpretations of the same raw ABSI value.
ABSI Calculation Example
Suppose an adult has the following measurements:
| Measurement | Value |
| Weight | 75 kg |
| Height | 175 cm |
| Waist circumference | 90 cm |
First, convert height and waist circumference into metres.
Height conversion
Waist circumference conversion
Step 1: Calculate BMI
Use the weight and height values in the BMI formula.
Calculation
Step 2: Calculate ABSI
Substitute the waist circumference, BMI, and height into the ABSI formula.
Calculation
Result: The calculated ABSI is approximately 0.0807, with a BMI of approximately 24.49 kg/m².
This result is the raw index. It should not be labelled low risk, average risk, or high risk without a suitable interpretation method and relevant reference data.
What Does Your ABSI Result Mean?
Your ABSI result describes waist circumference in relation to BMI and height. A higher value means your waist circumference is larger relative to those measurements under the ABSI formula.
A lower value means your waist circumference is smaller relative to the same measurements. Neither result, on its own, establishes whether you have a medical condition.
What is an ABSI z-score?
An ABSI z-score shows how far your ABSI value is from the mean of a reference population, measured in standard deviations. The mean and standard deviation should correspond to the appropriate age and sex categories.
ABSI z-score formula
Where:
- ABSI = Your calculated index.
- ABSIₘₑₐₙ = The mean ABSI for the selected reference group.
- ABSIₛᴅ = The standard deviation of ABSI in that group.
A positive z-score means the result is above the reference mean. A negative z-score means it is below the reference mean. A z-score near zero means it is close to the reference mean.
A z-score is a standardized comparison, not a probability of developing a disease or dying. Any risk estimate requires a separate statistical model.
Does a higher ABSI mean higher health risk?
The original 2012 study found an association between higher-than-average ABSI and mortality in the population studied. The researchers reported that mortality rates increased by approximately 33% per standard deviation of ABSI, with a 95% confidence interval of 20% to 48% (Krakauer & Krakauer, 2012).
That finding describes a statistical association in the study population. It does not mean that every person with a higher ABSI has a 33% greater personal risk of death. Individual risk depends on many factors, including medical history, age, and other health measures.
ABSI vs. BMI: What Is the Difference?
ABSI and BMI measure different aspects of body size. BMI compares weight with height, whereas ABSI incorporates waist circumference and adjusts it for BMI and height.
| Feature | ABSI | BMI |
| Main purpose | Measures waist size relative to height and BMI. | Measures weight relative to height. |
| Uses waist circumference | Yes. | No. |
| Uses height | Yes. | Yes. |
| Uses weight | Indirectly, through BMI. | Yes. |
| Result format | A small numerical index. | A value expressed in kg/m². |
| Interpretation | May be standardized against age- and sex-specific reference data. | Common adult categories use established BMI ranges. |
| Main limitation | Does not directly measure body fat or diagnose disease. | Does not distinguish fat from muscle or show where fat is stored. |
The US Centers for Disease Control and Prevention (CDC) explains that BMI does not measure belly fat directly and that excess abdominal fat can increase the risk of health problems (CDC, 2024). ABSI provides a different measure by incorporating waist circumference.
Using ABSI and BMI together can provide more information than relying on either measurement alone. Neither measure replaces a full health assessment.
How to Measure Waist Circumference Correctly
Accurate waist measurement matters because waist circumference is a direct input in the ABSI formula. An incorrect measurement can change the calculated result. The CDC recommends measuring around the middle, just above the hip bones, and taking the measurement after breathing out normally.
Follow these steps:
- Stand upright with your abdomen relaxed.
- Place a flexible tape measure around your waist, just above your hip bones.
- Keep the tape level around your body and snug without pressing into your skin.
- Breathe out normally and read the measurement.
- Record the value and unit before entering it into the calculator.
Use the same measurement method each time you repeat the calculation. Consistent technique makes changes in your recorded waist circumference easier to compare.
What Are the Limitations of ABSI?
ABSI can add information about body shape, but it has limits that matter when interpreting a result.
- It is not a diagnostic test. ABSI cannot confirm obesity, diabetes, cardiovascular disease, or another health condition.
- It does not measure body fat directly. The index is calculated from body measurements rather than an assessment of fat tissue.
- Reference data affect interpretation. A raw ABSI value cannot be assigned a universal risk category without a defined interpretation method.
- Population findings do not determine individual outcomes. Associations found in research may not apply equally to every population or person.
- Measurement errors affect the result. Incorrect height, weight, or waist measurements can change the calculation.
The 2020 European cohort study by Dhana and colleagues and other researchers examined ABSI in a large population and found that it could complement BMI in mortality risk assessment. Its findings support further use of the index in population research, not the use of ABSI as an independent clinical diagnosis (Dhana et al., 2020).
If you have concerns about abdominal fat, weight, or your overall health, discuss your measurements and other risk factors with a qualified healthcare professional.
References
- Krakauer, N. Y., and Krakauer, J. C. (2012). A new body shape index predicts mortality hazard independently of body mass index
- Centers for Disease Control and Prevention (2024). Healthy Weight
- Dhana, K., et al. (2020). A Body Shape Index (ABSI) achieves
Frequently Asked Questions
Is ABSI suitable for children and teenagers?
The original ABSI study examined adults aged 18 and older. Do not apply adult ABSI interpretations to children or teenagers without an appropriate, validated method for their age group.
Does ABSI measure body fat percentage?
No. ABSI is an index based on waist circumference, height, and BMI. It does not directly measure the percentage of your body weight that consists of fat.
What should you do if your ABSI result concerns you?
Discuss the result with a healthcare professional who can review your medical history, waist measurement, BMI, blood pressure, and other relevant health indicators before advising you.