BAI Calculator

Estimate Body Adiposity Index from hip circumference and height using the Bergman formula, with sex-specific underfat-to-obese categories.

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Sex

Units

Height (cm) Hip circumference (cm)

Measure at the widest point of the hips / buttocks.

23.0% Overfat

23.0%

BAI

Overfat

Category	BAI range
Underfat	< 8%
Normal	8–20%
Overfat	21–25%
Obese	> 25%

BAI Calculator — Body Adiposity Index

This calculator estimates your Body Adiposity Index (BAI) from hip circumference and height, and classifies the result using sex-specific ranges developed by Bergman et al. (2011).

What is BAI?

Body Adiposity Index was introduced by Bergman et al. (2011) as an alternative body fatness measure that does not require weight. The formula — (hip circumference in cm) / (height in m)^1.5 − 18 — was derived from a population study and produces a value that correlates with direct percentage body fat measurements from DXA scanning.

Unlike BMI, BAI uses hip circumference rather than weight, making it potentially more sensitive to differences in body fat distribution. Hip circumference captures gluteofemoral fat, which behaves differently from visceral abdominal fat.

Interpreting your BAI

BAI categories differ by sex. For men: underfat (<8%), normal (8–20%), overfat (21–25%), obese (>25%). For women: underfat (<21%), normal (21–33%), overfat (34–39%), obese (>39%). These cut-offs were set so that BAI values approximate direct body fat percentage measurements.

BAI should be interpreted alongside other body composition measures. It captures adiposity differently from BMI (which uses weight/height²) and waist circumference (which captures abdominal circumference). No single metric fully characterises body composition.

BAI versus BMI

Validation studies comparing BAI to criterion measures (DXA) show mixed results. Some studies found BAI performs better than BMI in certain ethnic groups; others found BMI remains more predictive. BAI may underestimate body fat in lean individuals and overestimate it in those with large, muscular hips.

BAI is most useful as a complementary measure alongside BMI and waist circumference rather than as a standalone assessment. Both measures together give a more complete picture of body composition than either alone.

Frequently asked questions

Is BAI more accurate than BMI?

It depends on the population. BAI was validated primarily in Mexican-American and African-American populations and shows reasonable correlation with DXA in those groups. Performance in other populations is more variable. For a general population screening tool, BMI and waist circumference remain more widely validated.

How do I measure hip circumference correctly?

Measure at the widest horizontal circumference of the hips and buttocks, standing upright with feet together. The tape should be level and snug but not compressing the skin.

What does the result mean for my health?

BAI provides a screening classification, not a diagnosis. Higher BAI categories are associated with increased cardiometabolic risk, similar to elevated BMI. If your result falls in the overfat or obese range, consider discussing body composition and lifestyle with your healthcare provider.

BAI Calculator

BAI Calculator — Body Adiposity Index

What is BAI?

Interpreting your BAI

BAI versus BMI

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