Enter your height, hip circumference, age group, and sex to calculate your Body Adiposity Index (BAI) — an estimate of body fat percentage based on hip size and height. Your results include your BAI value, body fat category (Underweight, Healthy, Overweight, or Obese), and a visual breakdown so you can compare against healthy ranges for your age and sex.
Body Adiposity Index (BAI)
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Body Fat Category
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Healthy BAI Range (Your Group)
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The Body Adiposity Index (BAI) is a method of estimating the percentage of body fat based on hip circumference and height. Unlike BMI, it does not require a weight measurement, making it useful when scales aren't available. It was developed as a more direct proxy for body fat percentage.
BAI is calculated as: BAI = (hip circumference in cm / (height in cm)^1.5) − 18. The result represents an estimate of body fat as a percentage of total body weight.
BMI uses weight and height, while BAI uses hip circumference and height. BAI is intended to directly estimate body fat percentage rather than a weight-to-height ratio. BAI can be more useful for people who don't have access to a scale, but both are screening tools rather than clinical diagnostics.
Healthy BAI ranges differ by age and sex. For males aged 20–40, a healthy range is approximately 8–21%. For females aged 20–40, it's roughly 21–33%. Ranges shift slightly upward for older age groups, reflecting natural body composition changes with age.
BAI was proposed as a more direct estimate of body fat, but research shows it is not consistently more accurate than BMI for all populations. Both methods are screening tools and neither replaces clinical assessments like DEXA scans or hydrostatic weighing for precise body fat measurement.
As people age, body composition naturally shifts — muscle mass tends to decrease while fat mass may increase even if total weight stays the same. The BAI reference ranges account for this by setting slightly higher thresholds for older age groups.
The BAI reference ranges provided are validated for adults aged 20–79. For individuals outside this range, the BAI formula can still calculate a value, but the category thresholds may not apply. Always consult a healthcare professional for guidance on body composition in younger or older individuals.
Stand with your feet together and measure around the widest part of your hips and buttocks, keeping the tape measure horizontal and snug but not tight against the skin. Take the measurement without clothing if possible for the most accurate result.