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Body Adiposity Index (BAI) Calculator

Estimate body fat percentage from hip circumference and height alone, using the Bergman et al. Body Adiposity Index formula, in metric or imperial units.

Body Adiposity Index
29.2%

How it works

The Body Adiposity Index (Bergman et al., 2011) estimates body fat percentage from just two measurements — hip circumference and height — deliberately without weight or a sex-specific coefficient, which is what makes it distinct from BMI and the U.S. Navy method: BAI = (hip circumference in cm ÷ (height in meters)^1.5) − 18.

The formula's coefficients are calibrated for centimeters and meters, so imperial (inch) entries are converted to metric before it runs and back afterward — the result is identical either way.

FAQ

Why doesn't this calculator ask for weight or sex?

That's the defining feature of the BAI formula as originally published — it was designed to estimate body fat percentage from a tape measure and a height alone, without needing a scale, and without a separate coefficient for men and women the way the Navy method or Devine's ideal-weight formula use.

How does BAI compare to BMI?

Both are quick estimates from simple measurements rather than direct body fat tests. BMI uses weight and height; BAI substitutes hip circumference for weight, on the reasoning that hip size tracks body fat more directly than total body weight does. Neither is as accurate as a DEXA scan, and independent validation studies since BAI's original publication have found it doesn't consistently outperform BMI — this calculator provides the published formula's number, not a claim that it's superior.

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