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Calculate your Body Adiposity Index (BAI) using hip circumference and height. An alternative to BMI for estimating body fat percentage.
Formula: BAI = (Hip Circumference / Height^1.5) - 18
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| Category | Men (BAI %) | Women (BAI %) |
|---|---|---|
| Underfat | < 8% | < 21% |
| Healthy | 8–21% | 21–33% |
| Overfat | 21–26% | 33–39% |
| Obese | > 26% | > 39% |
The Body Adiposity Index (BAI) is a method for measuring body fat percentage using only two measurements: hip circumference and height. Developed in 2011 by researchers at the Cedars-Sinai Medical Center, BAI was designed as a simpler alternative to BMI that more directly estimates body fat. The formula is BAI = (Hip cm / Height m^1.5) - 18. Unlike BMI, which uses weight and may misclassify muscular individuals, BAI focuses on hip size relative to height, which correlates more directly with adipose tissue. Normal BAI ranges are approximately 8–21% for men and 21–33% for women.
Stand with feet together and measure the widest part of your hips and buttocks in centimeters using a flexible tape measure.
Record your height in meters (e.g., 170 cm = 1.70 m).
Calculate BAI = (Hip cm / Height m^1.5) - 18. For example, hip = 100 cm, height = 1.70 m: BAI = (100 / 2.214) - 18 = 27.1%
Compare your BAI to healthy ranges: men 8–21% (healthy), women 21–33% (healthy). Values above these ranges indicate excess body fat.
BAI assesses body composition without a scale, useful when weight is unavailable or unreliable.
Elevated BAI correlates with higher risk of metabolic syndrome, heart disease, and type 2 diabetes.
Only two measurements needed — hip circumference and height — making it easy to track over time.
Used by clinicians as a complementary metric alongside BMI for a fuller picture of patient body composition.
Measure hips at the widest point for accurate results.
Use metric units (cm and m) — the formula doesn't work with imperial units directly.
BAI is less accurate for very tall or very short individuals.
Compare BAI alongside BMI for a more complete health picture.
BAI does not replace clinical body fat testing methods like DEXA.
A healthy BAI is approximately 8–21% for men and 21–33% for women. Values above these ranges suggest excess body fat and associated health risks.
BAI may be more accurate for some populations, particularly those with high muscle mass, since it uses hip circumference rather than total weight. However, neither metric replaces a clinical body fat assessment.
The BAI formula uses hip circumference in centimeters and height in meters. The result is expressed as a percentage representing estimated body fat.
The BAI formula was validated primarily for adults. For children and adolescents, age- and sex-specific growth charts and BMI percentiles are the recommended screening tools.
Measuring every 1–3 months is sufficient to track body composition changes. Daily measurements are not necessary and may show misleading fluctuations due to hydration and measurement variability.
A very low BAI (below 8% for men, below 21% for women) may indicate underfat status, which can be associated with hormonal disruptions, reduced bone density, and compromised immune function.
Accuracy depends on consistent technique: always measure at the widest point of the hips and buttocks, keep the tape parallel to the floor, and avoid compressing the skin. Repeated measurements by the same person improve consistency.
BAI can be less accurate for athletes with very large or very lean hip circumferences that don't reflect typical body fat distributions. Athletes may benefit more from DEXA scans or hydrostatic weighing for body composition analysis.
Results are for informational purposes only. Verify critical calculations with a qualified professional.