Body composition

Body Adiposity Index Calculator

BAI estimates body fat % from hip circumference and height, no weight needed.

Body Adiposity Index (BAI) estimates body fat percentage from hip circumference and height without needing weight. The formula: BAI = (hip cm / height m^1.5) − 18. Developed at USC Keck School of Medicine in 2011.

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Your daily target

· cal/day

Enter your details and click Calculate

  • BMR · cal/day at rest
  • BMI ·  
  • Lean body mass · kg

Pick your goal

Macros at maintenance

30% protein · 40% carbs · 30% fat

Advanced metrics

Numbers are estimates. Eat at your target for 2 to 3 weeks, track weight, and adjust by ±100 cal/day if it does not match your real maintenance. See how accurate is TDEE?

Show advanced metrics 12 metrics · 7 formulas · 2D macro selector · life-stage

All metrics

Calculate above to populate the full metric table.

All 7 BMR formulas (side-by-side)

Mifflin–St Jeor · Harris–Benedict (revised) · Katch–McArdle · Cunningham · Average · Simple multiplier · Custom

TDEE across activity levels

See how much your TDEE changes between sedentary and athlete. Highlighted bar is your current selection.

Macros: 2D selector

Goal × carb-split matrix: Cut / Maintain / Bulk × Low / Moderate / High carb.

Life-stage adjustments

Luteal phase · Pregnancy (T1/T2/T3) · Breastfeeding · Perimenopause · PCOS

BAI was proposed as an alternative to BMI that more directly correlates with body fat. It uses hip circumference rather than weight, sidestepping the muscle-vs-fat ambiguity.

BAI ranges (Bergman et al., 2011)

  • Men: normal 8–21%, overweight 21–26%, obese 26%+
  • Women: normal 21–33%, overweight 33–39%, obese 39%+

Frequently asked questions

How accurate is BAI compared to DEXA?
Bergman et al. (2011) found BAI correlated reasonably with DEXA body fat in their original sample. Follow-up studies have shown mixed results. BAI tends to over-estimate body fat in athletes and under-estimate in obese populations.
Why doesn't BAI use weight?
Avoiding weight is the entire point: it sidesteps the BMI confound where muscular people look "obese." Hip circumference correlates with fat storage independent of muscularity.
BAI or BMI, which should I use?
Most evidence supports waist-to-height ratio over both. For body composition, body fat percentage from a measurement (DEXA, calipers) is best. BAI is one signal among many.