Body Adiposity Index (BAI) Calculator
Estimate body fat percentage with the Body Adiposity Index (BAI) from hip circumference and height — no scale required.
How to use this tool
- Measure your hips at the widest point in centimetres.
- Measure your height in centimetres.
- Read your estimated body fat percentage.
- Compare it with the body-fat interpretation table below.
The Body Adiposity Index (BAI) calculator estimates body fat percentage from your hip circumference and height alone — useful when a scale is not available.
Formula
BAI (%) = hip circumference (cm) ÷ height (m)1.5 − 18
Height is in metres here, so a height of 175 cm becomes 1.75 m before it is raised to the power 1.5.
How it works
The Body Adiposity Index was introduced by Bergman and colleagues in Obesity (2011) as a way to estimate body fat percentage from hip circumference and height without needing body weight. Unlike BMI, BAI does not depend on a scale, which can make it convenient in field settings.
BAI tends to be most reliable around average builds and can over- or under-estimate fat at the extremes; several later studies found it no more accurate than BMI in some populations. Treat the result as one screening signal among several, alongside waist-based measures.
This calculator is provided for general information and education only and is not medical advice. Body-shape indices are screening estimates, not diagnoses. Always consult a qualified healthcare professional before making decisions about your health.
Worked example
Hip 100 cm, height 175 cm (1.75 m)
- Convert height to metres: 175 cm = 1.75 m
- Raise to the power 1.5: 1.751.5 = 2.315033
- Divide hip by that: 100 ÷ 2.315033 = 43.1959
- Subtract 18: 43.1959 − 18 = 25.1959
- Round to two decimals = 25.20%
Body Adiposity Index = 25.20%
General body fat percentage interpretation (adults)
| Category | Men | Women |
|---|---|---|
| Essential / very low | 2 – 5% | 10 – 13% |
| Athletic | 6 – 13% | 14 – 20% |
| Fitness | 14 – 17% | 21 – 24% |
| Average / acceptable | 18 – 24% | 25 – 31% |
| High | ≥ 25% | ≥ 32% |
Key terms
- Body Adiposity Index (BAI)
- An estimate of total body fat percentage calculated from hip circumference and height, with no weight term.
- Hip circumference
- The measurement taken around the widest part of the buttocks, used as a proxy for peripheral fat and pelvic frame.
- Adiposity
- The state of having excess body fat; the quantity these indices try to estimate.
Frequently asked questions
- Does BAI need my body weight?
- No. BAI is calculated entirely from hip circumference and height, which is its main practical advantage over BMI.
- How accurate is the Body Adiposity Index?
- BAI is a rough estimate. It performs reasonably near average builds but can drift at very low or very high body-fat levels, so use it alongside other measures.
- What is a healthy BAI?
- There is no single official cut-off; BAI is read like a body-fat percentage and interpreted using the sex-specific ranges in the table above.