What is the Body Adiposity Index (BAI)?
The Body Adiposity Index (BAI) was proposed in 2011 by researchers at the University of Southern California as a method to validate body fat percentages without needing to weigh a person. It is based on the ratio of hip circumference to height. The logic is that hip size is strongly correlated with total body fat in the general population.
BAI vs. BMI: What's the Difference?
BMI (Body Mass Index)
- Uses Weight and Height.
- Good for general population screening.
- Flaw: Cannot distinguish between muscle and fat. Often misclassifies athletes as overweight.
BAI (Body Adiposity Index)
- Uses Hip Circumference and Height.
- Does not require a scale.
- Advantage: Can be better for people who carry weight differently, but still has limitations with extreme muscularity.
Frequently Asked Questions
Is this as accurate as the Navy Method?
Generally, no. The US Navy Method uses more data points (neck, waist, and hips) to triangulate body fat distribution. BAI is considered a "Quick Check" alternative when a scale or full tape measurements aren't available.
Why hips?
Clinical studies have shown that hip circumference (adjusted for height) is strongly correlated with the percentage of body adiposity (fat tissue) in both men and women, often acting as a better proxy than weight alone.
Tools & Data Verified by the EverydayCalculators Medical Research Team.
Last updated: January 2026.