Body Adiposity Index Calculator
A clear, practical calculator with instant results and an explained formula.
Body Adiposity Index Calculator
How to use this calculator
Enter the values and calculate. Adjust inputs to compare results.
Hip circumference ÷ height^1.5 − 18; not a direct body-fat measurement.
Informational estimate only. Verify important financial, health, engineering, or regulatory decisions with a qualified professional.
Understanding the result
Body Adiposity Index (BAI) is an anthropometric formula based on hip circumference and height: hip circumference in centimetres ÷ height in metres raised to 1.5, minus 18. It is an indirect research-derived proxy, not a direct body-fat measurement.
Apply the units exactly
With hips of 100 cm and height of 1.70 m, BAI is 100 ÷ 1.70^1.5 − 18, or about 27.1. Entering height as 170 instead of 1.70 produces a meaningless result because the formula specifically requires metres for height.
Why BAI needs a warning label
BAI was proposed as a way to estimate adiposity without body weight, but validation studies have found meaningful error and population differences. Some research has found BMI or waist circumference more strongly associated with skinfolds or cardiovascular risk factors. BAI should not be read as an exact body-fat percentage.
Measurement and scope
- Measure hip circumference at the protocol’s specified widest point with a level tape.
- Use metres for height and centimetres for hips.
- Do not apply the adult equation to children; pediatric research uses different approaches.
- Avoid diagnosing obesity, metabolic disease or fitness from BAI alone.
If body composition matters clinically or for performance, choose a validated assessment method and interpret it with relevant history. Repeating BAI may track tape-measure change, but measurement error can look like biological change.
BAI can change because of a true circumference change or because the tape was placed differently. For longitudinal use, measure at the same site and under similar conditions, and avoid interpreting small fluctuations. Cross-person comparisons add further uncertainty because the relationship between body shape and body fat varies among populations and individuals.
Practical questions about Body Adiposity Index Calculator
Is BAI the same as body-fat percentage?
No. It is an indirect estimate and can differ substantially from measured body fat.
Why are two different units required?
The published formula uses hip circumference in centimetres and height in metres.
Can children use this equation?
No. The adult BAI formula has performed poorly in children and should not be substituted for pediatric assessment.
Is BAI better than BMI?
Not consistently; studies have found important limitations and population-dependent performance.
Health note: This page provides a general educational estimate. It is not medical advice, diagnosis, monitoring guidance or emergency care.