BAI Calculator
The BAI Calculator estimates your Body Adiposity Index — an estimate of body fat percentage from your hip circumference and height, without needing your weight. Enter your sex, height, and hip measurement, and it returns your BAI along with a category and the healthy range for your sex. BAI is an alternative to BMI that some find useful when weight isn't available.
Rates and fees change frequently. Always confirm the current figures
with the official authority before relying on this result.
- BAI was validated primarily on African-American and Mexican-American adults.
- Accuracy may differ across ethnicities and age groups.
Formula
BAI = (hip circumference (cm) / height (m)^1.5) − 18
- The Body Adiposity Index estimates body fat percentage from hip size and height, without requiring body weight.
- Formula: BAI = (hip circumference in cm ÷ height in metres^1.5) − 18.
- Input definitions: • Sex: healthy ranges differ between men and women. • Height: standing height in centimetres. • Hip circumference: measured around the widest part of the hips and buttocks, in centimetres.
- Healthy ranges are roughly 8–20% for men and 21–33% for women; above that is classed as overfat or obese.
- BAI is a screening estimate, not a precise body-fat measurement — methods like DEXA are far more accurate.
- It was validated mainly on specific populations, so accuracy can vary by ethnicity and age; treat it as a rough guide.
Example Calculation
Inputs
- Sex: male
- Height: 170 cm
- Hip Circumference: 95 cm
For a man 170 cm tall (1.7 m) with a 95 cm hip circumference: BAI = (95 ÷ 1.7^1.5) − 18 ≈ (95 ÷ 2.217) − 18 ≈ 24.9%. That sits in the overfat range for men (healthy is 8–20%).
Frequently asked questions
What is the Body Adiposity Index (BAI)?
BAI is an estimate of body fat percentage calculated from hip circumference and height. Unlike BMI, it doesn't use body weight.
How is BAI different from BMI?
BMI uses weight and height, while BAI uses hip circumference and height. BAI aims to estimate body fat directly rather than overall mass.
What is a healthy BAI?
Roughly 8–20% for men and 21–33% for women. Higher values fall into the overfat or obese categories.
How do I measure my hip circumference?
Wrap a tape measure around the widest part of your hips and buttocks, keeping it level and snug but not tight.
Is BAI accurate?
It's a quick screening estimate. It was validated on specific populations and can be less accurate for others, so don't treat it as a precise body-fat reading.
Should I use BAI or BMI?
BAI is handy when you can't weigh yourself but can measure your hips. For most people, using both alongside other measures gives a fuller picture.
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