Free testosterone estimator

🧪 Free Testosterone Estimator

Enter your lab values to estimate bioavailable and free testosterone.
Uses the Vermeulen equation — the same method most endocrinologists reference.

💡 Where to find these numbers: Check your blood test report. Total Testosterone, SHBG, and Albumin are standard items in a hormone panel. If Albumin isn't listed, 4.3 g/dL is a standard assumed value.

 US Units (ng/dL)  SI Units (nmol/L)

Total Testosterone (ng/dL)

Typical male range: 300–1000 ng/dL

SHBG — Sex Hormone-Binding Globulin (nmol/L)

Typical male range: 10–57 nmol/L. Always reported in nmol/L regardless of unit system.

Albumin (g/dL) — optional

Estimated Free Testosterone

—

Total T

—

SHBG

—

Free T %

—

Free Testosterone Reference Ranges (pg/mL) — Men 40–49:

Low: below 6.8 pg/mL

Low-Normal: 6.8–9.0 pg/mL

Normal: 9.0–26.5 pg/mL

Ranges vary by lab and age. Use these as a general guide only — your doctor interprets results in clinical context.

This calculator uses the Vermeulen equation (Vermeulen A et al., J Clin Endocrinol Metab, 1999) and provides estimates only.
It is not a diagnostic tool. Always discuss your results with a qualified healthcare provider.

How Magnesium Affects SHBG and Free Testosterone →