Calculate Body Adiposity Index (BAI) from hip circumference and height, or solve for hip or height using BAI and unit conversions.

BAI Calculator

Measurement tip: Use a flexible tape, stand relaxed, keep the tape level, and measure hips around the widest part of the buttocks/hips without compressing the tissue.

Enter any 2 values to calculate the missing variable

Disclaimer: For informational purposes only; not medical advice. BAI is an estimate (not a diagnostic test) and can be inaccurate for some people (including adolescents, pregnancy, older adults, and very athletic or atypical body types). If you have concerns about weight, nutrition, or body image—including eating disorders—seek help from a qualified healthcare professional.

BAI Formula

The following formula is used to calculate a body adiposity index.

BAI = (HIP / (HEIGHT^{1.5})) - 18
  • Where BAI is the body adiposity index (%)
  • HIP is your hip circumference (cm)
  • Height is your height (m)

The BAI formula was originally proposed in academic research (often cited as Bergman et al., 2011). For interpretation and screening guidance, consult reputable public health/medical organizations and/or a licensed clinician.

BAI Definition

What is BAI?

BAI is a term that stands for body adiposity index. It’s used to estimate body fat percentage using hip circumference and height.

It should be noted that this is only an estimation, and there are many ways to estimate body fat amounts and percentages.

BAI Limitations

BAI is a screening-style estimate and may not reflect true body fat percentage for everyone.

  • Accuracy can vary by sex, ethnicity, age, and body type.
  • It may be less reliable for children/adolescents, pregnancy, older adults, and some athletic or atypical body types.
  • Clinical body composition methods (such as DXA scans or other validated assessments) may be used when medically appropriate.

Example Problem

How to calculate BAI?

First, determine the circumference of your hips. This can be done with a tape measure and is typically taken around the widest part of the buttocks/hips. For this example, the hip circumference was found to be 94 cm.

Next, determine the person’s height. In this example, the person is found to be 1.85 meters.

Finally, calculate the BAI using the formula above:

BAI = ( HIP / (HEIGHT^1.5)) – 18

BAI = ( 94 / (1.85^1.5)) – 18

BAI ≈ ( 94 / 2.5163 ) – 18 ≈ 19.36%

FAQ

What is the difference between BAI and BMI?

BAI (Body Adiposity Index) is intended to estimate body fat percentage using hip circumference and height. BMI (Body Mass Index) is a screening index calculated from weight and height (BMI = weight/height²); it does not directly measure body fat percentage, although it often correlates with adiposity at the population level.

Why is hip circumference used in calculating BAI?

Hip circumference is included in the BAI formula because it was found to correlate with body fat in the research that proposed BAI. However, BAI accuracy can vary by sex, ethnicity, age, and body type, and it is not universally more accurate than other measures (such as BMI, waist circumference, or more direct body-composition methods).

Can BAI be used for all age groups?

BAI was developed using adult populations and may be less accurate in children/adolescents, older adults, and some athletic or atypical body types. For these groups, other age- and population-appropriate methods may be more reliable.