A Body Shape Index Calculator

Since the early 1990s, Body Mass Index, or BMI, has become an almost universally used indicator of obesity with obesity being a leading cause of death worldwide. Recently a new measure of obesity, ABSI (A Body Shape Index), has shown to be a better predictor of mortality. Use this calculator to calculate your ABSI.

BMI doesn't tell you anything about where you're carrying your weight. Numerous studies have found that having an apple shaped body or carrying excess belly fat is riskier than having a pear shaped body or heavy bottom.

Another flaw with BMI is that it does not distinguish between fat and muscle. It sets health categories based on height and weight alone. Two individuals of identical weight and height could both be classified as overweight even though one may be muscular with a healthy amount of body fat and the other with excessive body fat and little muscle.

To address some of the limitations of BMI, City College of New York researchers developed a new formula they call A Body Shape Index or ABSI. It was developed as a way to quantify the risk associated with abdominal obesity where obesity is indicated by a wide waist circumference (WC) relative to a person's height and BMI.

Medical exam and mortality data was analysed on a sample of more than 14,000 adults who participated in the United States (USA) National Health and Nutrition Examination Survey (NHANES) 1999–2004. They found that an above average ABSI was associated with substantially higher risk of death. Additionally, excess mortality hazard associated with high ABSI was greater than that associated with above-average BMI or waist circumference.

The study concludes that even though you may have a normal BMI, you may be at a greater risk of dying sooner if you carry excessive weight in your midsection relative to your height and weight. ABSI expresses the EXCESS risk from high waist circumference in a convenient form that is complementary to BMI and to other known risk factors.

Also, your body's percentage of body fat may provide you with an additional picture of your overall health. You can use this calculator to estimate your body fat percentage and associated risk.

How to Measure Waist Circumference

It's very important to take an accurate measurement of your waist circumference to produce meaningful calculation results. A small error in the measurement can result in large errors in the calculated results. Follow the Centers for Disease Control and Prevention guidelines to correctly measure your waist. Use a flexible measuring tape made of non-stretchable material.

1. Stand and place a tape measure around your middle, just above your hipbones.
2. Make sure tape is horizontal around the waist.
3. Keep the tape snug around the waist, but not compressing the skin.
4. Measure your waist just after you breathe out.

See here for additional instructions on how to properly measure waist circumference.

Comparisons With Other Anthropometric Indices

A 2020 study [4] was conducted on a large group of people in Europe to clarify the usefulness of various body shape indices when assessing the risk of obesity-related death. The study examined various waist circumference-based anthropometric indices for comparison, such as:

• ABSI (A Body Shape Index) 
• BRI (Body Roundness Index)
• WHR (Waist-to-Hip Ratio)
• WWI (Weight-adjusted Waist Index)

The study found that a Body Shape Index (ABSI) provides a more accurate risk assessment for mortality than other measures. ABSI, which is designed to be independent of BMI, works well with BMI and helps to categorize the risk effectively for underweight and obese individuals, as well as for those with average weight and overweight BMI.

Caution! This calculator is intended for illustrative and educational purposes only and not for medical use. ABSI is designed to be used together with the more familiar body mass index (BMI) and not replace it.