Testosterone (Free)

Calculated Free Testosterone estimates the unbound fraction (~2% of total testosterone). More clinically relevant than total testosterone when SHBG is abnormal.

Also known as:

Calculated Free Testosterone (Vermeulen)

fTST

Testosterone (Free) ranges for

Interpret your result

"Normal" lab range for Testosterone (Free) is between 46 and 224 pg/mL for males:

224

According to European Academy of Andrology, Testosterone (Free) should be above 63.45 pg/mL for males:

69.22

According to OptimalDX, Testosterone (Free) should be between 150 and 224 pg/mL for males:

150

224

Optimal range

Optimal range for Testosterone (Free) appears to be between 100 and 224 pg/mL for males:

100

224

300

Why this optimal range?

Preliminary range is based on functional health organizations including but not limited to those listed above.

Why calculated, not measured? Direct immunoassay methods for free testosterone are unreliable due to cross-reactivity with other steroids and dramatic differences in reference ranges between labs — e.g., LabCorp's analog immunoassay produces values ~4× lower than Quest's method, with no way to convert between them. The gold-standard equilibrium dialysis is too complex and costly for routine use.

The Vermeulen calculation, using total testosterone, SHBG, and albumin, is the most robust approximation — largely independent of SHBG, albumin, and T levels — unlike competing formulas whose accuracy degrades at extreme SHBG values.

This page is marked as a work-in-progress.

The optimal range is derived from a limited number of sources and is subject to change.

Your interpretation

For low

For high

Enter you value above to interpret your result.

100% free and private. No data will leave your computer.

Discover the Reasons

Discover the possible reasons behind high or low values.

Know the Consequences

Understand the potential consequences and symptoms.

Fix it with interventions

Explore possible interventions and discuss them with your doctor.

About the site author
My personal mission is to extend human lifespan by collectively adding 1 million years to people's lives.
That’s why I made this site 100% free—no sign-up, no email. Just instant results.
Zsolt Szabo
Precision Health Consultant for Longevity Clinics, Biohacker, and Software Engineer

Please send me relevant research and feedback.

Any feedback is welcome at .

I am particularly interested in research on biomarkers associated with all-cause mortality and on defining optimal reference ranges.