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BAI uses hip circumference and height only. It can be useful when weight is not available, but it does not replace clinical body-composition testing.
A BAI calculator estimates Body Adiposity Index, a simple body-fat estimate based on height and hip circumference. Unlike BMI, BAI does not require body weight. This makes it useful for quick educational checks when a scale is not available.
BAI Formula
The standard Body Adiposity Index formula uses hip circumference in centimeters and height in meters.
BAI = Hip Circumference (cm) / Height (m)1.5 - 18
The result is commonly read as an estimated body-fat percentage. The calculator automatically converts inches to centimeters when US Units are selected.
How to Use This BAI Calculator
- Select Metric or US Units.
- Choose a broad reference group if you want a simple comparison label.
- Enter your height and hip circumference.
- Read the estimated body-fat percentage, BAI value, and hip-to-height ratio.
How to Measure Hip Circumference
Stand upright with your feet close together. Wrap a flexible measuring tape around the widest part of your hips and buttocks. Keep the tape level, snug, and not pulled tight into the skin. For tracking over time, measure at the same point each time.
BAI vs BMI
BMI uses weight and height, while BAI uses hip circumference and height. BAI may be helpful as a quick body-fat estimate, but it can still be affected by body shape, muscle mass, age, sex, and ethnicity. For a fuller health picture, compare BAI with waist measurement, lifestyle factors, blood pressure, lab results, and professional advice.
Important Health Note
This BAI calculator is for education and general wellness tracking only. It does not diagnose obesity, metabolic risk, or any medical condition. If you are making health, diet, or exercise decisions, consult a qualified healthcare professional.
Frequently Asked Questions
What does BAI mean?
BAI means Body Adiposity Index. It is a formula-based estimate of body fat percentage using hip circumference and height.
Does BAI need body weight?
No. BAI does not use body weight. It only needs hip circumference and height.
Is BAI more accurate than BMI?
BAI and BMI measure different things and both have limitations. Some studies have found that BAI is not always more accurate than BMI, waist circumference, or hip circumference alone. Use it as a general estimate, not a final health judgment.
Reference: Bergman RN et al. introduced BAI in A Better Index of Body Adiposity.