BAI Calculator
Estimate Body Adiposity Index (BAI) from hip circumference and height, then interpret your result with sex- and age-based ranges.
Body Adiposity Index
Elevated adiposity range relative to this sex and age band.
BAI Interpretation RangesMENAGES 20-39
These ranges are used to interpret BAI values as an estimated adiposity percentage by sex and age band. Use them as trend categories, not diagnosis.
| BAI RANGE | CATEGORY |
|---|---|
| 0.0-8.0 | Underweight Lower-than-typical adiposity for this sex and age band. |
| 8.0-21.0 | Healthy Typical healthy adiposity range for this sex and age band. |
| 21.0-26.0 | Overweight Elevated adiposity range relative to this sex and age band. |
| 26.0+ | Obese High adiposity range; prioritize sustainable long-term habits. |
What This BAI Calculator Shows
Body Adiposity Index (BAI) is an anthropometric estimate intended to approximate body fat percentage from hip circumference and height. Unlike BMI, it does not use body weight.
This makes BAI useful when you want a tape-measure metric that can be tracked over time with consistent measurement technique.
BAI Formula Used
This calculator uses the standard BAI equation with hip in centimeters and height in meters:
BAI = (hip circumference / (height^1.5)) - 18
The output is shown as a percentage-like adiposity estimate. Interpretation ranges are applied by sex and age band.
How To Measure Hip Circumference Correctly
- Stand upright with feet close together and weight evenly distributed.
- Wrap the tape around the widest point of the hips/glutes.
- Keep the tape level and snug without compressing skin.
- Take 2 to 3 readings and use the average.
- Use similar hydration and time-of-day for repeat tracking.
BAI vs Other Body Composition Tools
BAI can be practical for trend tracking, but it is still an estimate. It should be interpreted with context and compared to other methods.
For waist-based alternatives, compare with the BRI Calculator and RFM Calculator. For caliper-based body-fat estimates, use the Skinfold Body Fat Calculator.
If you want lean-mass context in parallel, run the Lean Body Mass Calculator and FFMI Calculator.
Limitations
BAI does not directly measure fat tissue and can over- or under-estimate adiposity depending on body shape, fat distribution, frame size, and athletic build.
For best use, track BAI over time with consistent inputs and pair it with progress photos and additional body composition metrics.
References
- Bergman RN, et al. A better index of body adiposity (BAI).PubMed record
- Freedman DS, et al. The body adiposity index and cardiovascular risk factors.PubMed record
- Johnson W, et al. BAI, BMI, and body fat percentage in adults.PubMed record