By Zencalcy Editorial TeamLast reviewed About us
The Body Adiposity Index (BAI) estimates body fat percentage using only hip circumference and height. It was proposed as an alternative to BMI that does not require a scale. BAI performs reasonably in population studies but is less reliable for very muscular people and for some ethnic groups.
Estimate body fat percentage from hip circumference and height.
BAI = hip(cm) ÷ height(m)^1.5 − 18
The result is read as an estimate of body fat percentage. Bergman et al. (2011) proposed the index and sex-specific categories; it is a population-level estimator, not a direct measurement.
| Symbol | Meaning |
|---|---|
| BAI | Body Adiposity Index, interpreted as estimated body fat percentage. |
| hip | Hip circumference in centimetres at the widest point. |
| height | Standing height in metres. |
1.75^1.5 = 2.315. BAI = 100 ÷ 2.315 − 18 = 43.2 − 18 = 25.2%. That falls in the healthy range for women and the overweight range for men under the published cutoffs.
BAI was designed to be simple: a tape measure and a height, no scale, no sex-specific equation in the core formula. That makes it attractive in field settings. Its weakness is that hip circumference is strongly influenced by muscle and skeletal frame, not only fat. Sprinters, dancers and people who lift weights often get a BAI that looks higher than their measured body fat. Conversely, someone with a large waist but narrow hips can look leaner on BAI than they are. The index also varies across populations, which is why later studies proposed ethnicity-specific adjustments. Used as a trend within one person, BAI is still informative: if hip and height stay stable while the number changes, something has changed in body composition or measurement technique. For clinical decisions, pair it with waist circumference and, where available, a direct body-composition measurement.
Continue with the ABSI Calculator (A Body Shape Index), Adjusted Body Weight Calculator, or the Body Frame Size Calculator — or browse more body measurements tools and all health calculators.
Also see the Body Fat Calculator.
For men, under 8% is underfat, 8–21% healthy, 21–26% overweight and above 26% obese. For women, under 21% is underfat, 21–33% healthy, 33–39% overweight and above 39% obese.
Every result is a screening estimate from published anthropometric equations, not a diagnosis or a measurement of body composition. Tape measurements should be taken snugly against the skin without compressing it, at the landmarks named in each tool. Equations were derived in specific populations and can be less accurate for athletes, older adults, children, pregnant people and people with significant oedema.
Reference material used to build and check this calculator:
Last reviewed: September 2026. See how we build and check every tool on the about page.
Content updated: September 2026