Free Androgen Index (FAI)
The Free Androgen Index is calculated from total testosterone and SHBG and estimates the proportion of biologically available testosterone. It is particularly useful in women to evaluate hirsutism, acne, and polycystic ovary syndrome, where an elevated FAI reflects functional androgen excess. In men it is a secondary measure when SHBG levels are abnormal.
2 providers include this
Additional Specialized Tests
Men:14.8-94.8, Women:0.8-11.0
What is Free Androgen Index (FAI)?
The Free Androgen Index is calculated from total testosterone and SHBG and estimates the proportion of biologically available testosterone. It is particularly useful in women to evaluate hirsutism, acne, and polycystic ovary syndrome, where an elevated FAI reflects functional androgen excess. In men it is a secondary measure when SHBG levels are abnormal.
Why It Matters
Indicates bioavailable testosterone. Useful in women with PCOS or hirsutism. Better reflects androgen status than total testosterone alone.
Which Providers Test Free Androgen Index (FAI)?
Full Provider Comparison
| Provider | Includes | Annual Cost | Biomarkers |
|---|---|---|---|
 Superpower | ✓ | $199 | 100+ (150 with ratios) |
 WHOOP Advanced Labs | — | $349 | 65 |
 Labcorp OnDemand | — | $398 | 40+ |
| — | $486 | 40+ | |
| — | $449 | 288 | |
| — | $349 | 100+ | |
| — | $829 | 54 | |
 Function Health | — | $365 | 160+ |
| — | $250 | 65 | |
| — | $495 | 80+ | |
| — | $895 | 100+ | |
| — | $1950 | 130+ | |
| — | $375 | 95+ | |
| — | $Varies | 75+ | |
| — | $190 | 100+ | |
| — | $99 | 50 | |
| ✓ | $124 | 60 | |
| — | $349 | 130+ | |
| — | $349 | 80+ | |
| — | $375 | 85 | |
| — | $700 | 128 | |
| — | $99 | 100+ |
Frequently Asked Questions
What is Free Androgen Index (FAI)?
The Free Androgen Index is calculated from total testosterone and SHBG and estimates the proportion of biologically available testosterone. It is particularly useful in women to evaluate hirsutism, acne, and polycystic ovary syndrome, where an elevated FAI reflects functional androgen excess. In men it is a secondary measure when SHBG levels are abnormal.
What is the optimal range for Free Androgen Index (FAI)?
The standard reference range for Free Androgen Index (FAI) is Men:14.8-94.8, Women:0.8-11.0. Optimal ranges may differ based on individual health goals and expert recommendations.
Which blood test providers include Free Androgen Index (FAI)?
2 out of 22 blood testing providers include Free Androgen Index (FAI) in their panels. This biomarker has limited availability.
What category does Free Androgen Index (FAI) fall under?
Free Androgen Index (FAI) is categorized under Additional Specialized Tests. This category includes biomarkers that help assess related aspects of health and wellness.
Medical Disclaimer
This information is for educational purposes only and is not medical advice. Always consult with a qualified healthcare provider about your specific health needs.
Last reviewed:2026-04-12