Calculate Body Adiposity Index (BAI) from hip circumference and height, or solve for hip or height using BAI and unit conversions.
Disclaimer: For informational purposes only; not medical advice. BAI is an estimate (not a diagnostic test) and can be inaccurate for some people (including adolescents, pregnancy, older adults, and very athletic or atypical body types). If you have concerns about weight, nutrition, or body image—including eating disorders—seek help from a qualified healthcare professional.
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BAI Formula
The Body Adiposity Index, or BAI, estimates body fat percentage from hip circumference and height. The calculator uses hip circumference in centimeters and height in meters for the main formula.
BAI = (Hip / Height^1.5) - 18
- BAI = Body Adiposity Index, expressed as a percentage
- Hip = hip circumference in centimeters
- Height = height in meters
If you leave hip circumference blank, the calculator rearranges the formula to solve for hip circumference:
Hip = (BAI + 18) * Height^1.5
If you leave height blank, the calculator rearranges the formula to solve for height:
Height = (Hip / (BAI + 18))^(2/3)
The calculator also converts your selected units before applying the formula:
Hip_cm = Hip_in * 2.54
Height_m = Height_cm * 0.01
Height_m = Height_in * 0.0254
Height_m = (Feet * 12 + Inches) * 0.0254
- Hip_cm = hip circumference converted to centimeters
- Hip_in = hip circumference entered in inches
- Height_m = height converted to meters
- Height_cm = height entered in centimeters
- Height_in = height entered in inches
- Feet and Inches = height entered in feet and inches
To calculate BAI, enter hip circumference and height, then leave BAI blank. To calculate a missing hip circumference or height value, enter the other two values and leave the unknown field blank.
BAI Result Ranges
BAI is an estimate of body fat percentage. The ranges below are general adult reference ranges and should not be treated as a medical diagnosis.
| Group | Lower body fat estimate | Moderate range | Higher body fat estimate |
|---|---|---|---|
| Adult men | Below about 8% | About 8% to 25% | Above about 25% |
| Adult women | Below about 21% | About 21% to 38% | Above about 38% |
Unit Conversion Reference
| Measurement | Entered unit | Conversion used |
|---|---|---|
| Hip circumference | Inches | Multiply by 2.54 to get centimeters |
| Height | Centimeters | Multiply by 0.01 to get meters |
| Height | Inches | Multiply by 0.0254 to get meters |
| Height | Feet and inches | Convert to total inches, then multiply by 0.0254 |
BAI Calculation Examples
Example 1: Calculate BAI
You have a hip circumference of 94 cm and a height of 1.85 m.
BAI = (94 / 1.85^1.5) - 18
BAI = 19.36%
The estimated BAI is 19.36%.
Example 2: Calculate hip circumference
You have a BAI of 25% and a height of 1.70 m.
Hip = (25 + 18) * 1.70^1.5
Hip = 95.25 cm
The estimated hip circumference is 95.25 cm.
FAQ
What is BAI?
BAI stands for Body Adiposity Index. It is a body fat estimate based on hip circumference and height. Unlike BMI, it does not use body weight. BAI can be useful as a simple screening estimate, but it does not directly measure body fat.
How should I measure hip circumference for BAI?
Stand relaxed and use a flexible tape measure. Keep the tape level around your body and measure around the widest part of your hips and buttocks. Do not pull the tape so tightly that it compresses the tissue.
Is BAI more accurate than BMI?
BAI and BMI estimate different things using different inputs. BMI uses weight and height, while BAI uses hip circumference and height. Neither method directly measures body fat. For a more complete assessment, body composition methods such as skinfold testing, bioelectrical impedance, DEXA, or clinical evaluation may be more informative.
