Body Adiposity Index (BAI) Calculator

BAI estimates body fat percentage without needing weight. Informational only.

How the Math Works

The Body Adiposity Index (BAI) is calculated using the formula BAI = (hip circumference ÷ height^1.5) − 18. Here, hip is measured around the widest part of the buttocks in centimeters, and height is in meters. The exponent 1.5 represents the square root of height cubed, which normalizes the relationship between hip and height. Subtracting 18 adjusts the result to align with body fat percentage estimates, providing a quick mathematical approximation of adiposity.

Practical Applications

To use the BAI calculator, first measure your hip circumference at its widest point using a flexible tape measure and record your height in meters. Input these values into the formula: divide your hip measurement by your height raised to the 1.5 power, then subtract 18. For example, a hip of 100 cm and height of 1.75 m yields BAI ≈ 25.2%. This calculation helps estimate body fat without specialized equipment, making it ideal for personal health tracking or fitness assessments.

Day-to-Day Use

The BAI calculator offers a simple, accessible tool for monitoring body fat percentage in daily life. By regularly calculating BAI, individuals can track changes related to diet, exercise, or weight loss efforts without costly equipment. It also raises awareness of health risks linked to excess adiposity, empowering users to make informed decisions about their lifestyle. While not as precise as clinical methods, its ease of use makes it valuable for quick self-assessments at home or in the gym.

Worked example

100 cm hip, 175 cm → ~25.2%.

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