BAI Calculator — Body Adiposity Index
The Body Adiposity Index (BAI) estimates your percentage body fat from just two measurements: hip circumference and height. No scale needed. Enter your measurements and sex to see your BAI and how it compares to healthy ranges.
cm
cm
Sex
Estimated body fat percentage — Bergman et al. 2011 formula
- 1
Height in metres
170 cm ÷ 100 = 1.7 - 2
Height^1.5
1.7^1.5 = 2.2165 - 3
Body Adiposity Index
95 ÷ 2.2165 − 18 = 24.9
How does this calculator work?
BAI = (hip in cm) ÷ (height in m)^1.5 − 18. It estimates body fat % without weighing — healthy ranges are 8–20 % for men and 21–33 % for women (Bergman et al. 2011). Measure the widest point of your hips; accuracy is lower for very muscular or atypically proportioned individuals.
Formula
How this is calculated
The Body Adiposity Index was proposed by Bergman et al. in 2011 (published in Obesity) as an alternative to BMI that better predicts body fat percentage without requiring weight. The formula is: BAI = hip_cm ÷ height_m^1.5 − 18. Hip circumference strongly correlates with fat mass, especially in the lower body, while dividing by height^1.5 (rather than height^2 as in BMI) accounts for the fact that hip width scales slightly differently with body size.
In validation studies on diverse populations (African-American and Hispanic adults), BAI correlated well with DEXA-measured body fat (r ≈ 0.79). The offset of 18 was chosen to shift the output to a percent body fat scale. Reference ranges differ by sex — women naturally carry more body fat than men, so the healthy range for women (21–33 %) is higher than for men (8–20 %).
Limitations: like BMI, BAI is a population-level screening tool, not a clinical body-composition measurement. It may be less accurate for people who are very tall or short, highly muscular (which inflates hip circumference without increasing fat), or from ethnic groups underrepresented in the original validation studies. Accurate body fat measurement requires DEXA, hydrostatic weighing, or air displacement plethysmography.
Frequently asked questions
BMI uses weight and height; BAI uses hip circumference and height, requiring no scale. BAI is claimed to directly estimate body fat percentage, whereas BMI is a weight-for-height index that does not directly distinguish fat from muscle. In practice, both are screening proxies — neither replaces clinical body-composition testing.
Measure at the widest point of your hips and buttocks, typically about 20 cm below your natural waist. Stand upright, relaxed, with feet together, and hold the tape horizontal. Take two readings and average them.
For men, 8–20 % is the healthy range (Bergman 2011 reference); below 8 % is underfat, 20–25 % is overfat, and above 25 % is obese. For women the healthy range is 21–33 %, with obesity above 39 %. These are the same cutoffs used in the original BAI publication.
Also known as
TG we-Calculate Editorial Team. (2026). BAI Calculator — Body Adiposity Index [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/bai-calculator
TG we-Calculate Editorial Team. "BAI Calculator — Body Adiposity Index." TG we-Calculate. 2026. https://we-calculate.com/calculator/bai-calculator.
TG we-Calculate Editorial Team, "BAI Calculator — Body Adiposity Index," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/bai-calculator
@misc{wecalculate_bai_calculator, title = {BAI Calculator — Body Adiposity Index}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/bai-calculator}}, year = {2026}, note = {TG we-Calculate} }
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