Free testosterone (direct) measures the unbound, biologically active testosterone in your blood. Only about 1–3% of total testosterone circulates as free testosterone, but this is the active form that enters cells and exerts hormonal effects.
Most searches for free testosterone relate to female levels. Free testosterone in women is much lower than in men (0.1–6.4 pg/mL), and even small increases can be clinically significant. In women, elevated free testosterone is most commonly associated with polycystic ovary syndrome (PCOS).
Free testosterone — quick answer
Free testosterone (direct) measures the unbound, biologically active testosterone in blood.
Normal range:
- Men (adult): 35–155 pg/mL
- Women (adult): 0.1–6.4 pg/mL (LabCorp equilibrium dialysis reference)
High: PCOS (women), steroid use or tumors (men) Low: aging, high SHBG, hypogonadism
Also called: Free Testosterone Direct, Testosterone Free (Direct), Free Testosterone LC
What is "Free Testosterone Direct"?
"Free testosterone direct" refers to a specific laboratory method — direct measurement of free testosterone using equilibrium dialysis or mass spectrometry — as opposed to calculated free testosterone, which is derived mathematically from total testosterone, SHBG, and albumin values. The direct method is more accurate when SHBG levels are abnormal.
You may see this test reported as:
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Free Testosterone, Direct
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Free Testosterone (Direct)
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Testosterone, Free (Direct)
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Free Testosterone Direct LC (LabCorp)
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Free Testosterone LC-MS/MS (mass spectrometry method)
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Free Testosterone, Direct Female (female-specific ordering)
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WarningLow Free Testosterone (Direct) — portal flag meaning the result fell below the reference range
What is the difference between free and total testosterone?
Total testosterone measures all testosterone in the blood — bound and free combined. It is the standard first-line test.
Free testosterone measures only the unbound, active fraction. It is particularly valuable when:
- Total testosterone is normal but symptoms of deficiency or excess persist
- SHBG is elevated (which reduces free testosterone disproportionately)
- SHBG is low (which elevates free testosterone relative to total)
- Evaluating testosterone status in women, where absolute levels are low and small changes matter more
Calculated free testosterone uses the Vermeulen equation incorporating total testosterone, SHBG, and albumin. Direct free testosterone measures the free fraction directly and is generally preferred for clinical decision-making when SHBG is abnormal.
Normal range — women
Free testosterone levels in women are significantly lower than in men. Reference ranges vary by laboratory method, age, and menopausal status. Always refer to your specific lab's reference range printed alongside your result.
| Life stage | Normal range (pg/mL) | Notes |
|---|---|---|
| Premenopausal adult (20–49) | 0.1–6.4 | LabCorp equilibrium dialysis |
| Premenopausal adult (alternate method) | 0.3–4.2 | Varies by assay; some labs use this range |
| Postmenopausal | 0.1–3.8 | Lower due to reduced ovarian production |
| Pregnancy | Not interpretable | Standard ranges do not apply |
Note on lab variability: Women's normal ranges vary more than men's depending on the assay used. LabCorp equilibrium dialysis uses 0.1–6.4 pg/mL for premenopausal adults; other methods may report a narrower range such as 0.3–4.2 pg/mL. The range printed on your report is the one to use for interpretation.
Normal free testosterone levels for women by age
Levels decline with age, most sharply around menopause:
- 20s–30s: typically 1.0–6.4 pg/mL
- 40s (perimenopause): typically 0.5–4.5 pg/mL
- Postmenopausal (50+): typically 0.1–3.8 pg/mL
These are approximate ranges. Individual variation is significant and clinical interpretation always requires symptom context.
Normal range — men
Reference ranges for pediatric males are based on Endocrine Society and laboratory-validated data. Adult ranges reflect the most commonly used laboratory thresholds.
| Age | Normal range (pg/mL) | Normal range (ng/dL) | Normal range (pmol/L) |
|---|---|---|---|
| 0–9 years | <1 | <0.1 | <2.9 |
| 10–11 years | <4 | <0.4 | <11.6 |
| 12–13 years | <68 | <6.8 | <197 |
| 14–15 years | 2–95 | 0.2–9.5 | 5.8–275 |
| 16–17 years | 26–119 | 2.6–11.9 | 75–345 |
| 18–49 years (adult) | 35–155 | 3.5–15.5 | 101–447 |
| 50–69 years | 40–140 | 4.0–14.0 | 115–404 |
| 70+ years | 30–120 | 3.0–12.0 | 87–346 |
Note: Free testosterone declines gradually in men with age — approximately 1–2% per year after age 30–40. The adult male HealthMatters optimal range of 35–155 pg/mL reflects the broad adult reference; levels at the lower end of this range are more typical of older men.
Unit conversion
Free testosterone is commonly reported in pg/mL, ng/dL, or pmol/L. Many users search how to convert between these units.
| To convert | Multiply by |
|---|---|
| pg/mL → ng/dL | ÷ 10 |
| ng/dL → pg/mL | × 10 |
| pg/mL → pmol/L | × 2.887 |
| pmol/L → pg/mL | ÷ 2.887 |
| ng/dL → nmol/L | × 0.03467 |
Example: 5 pg/mL = 0.5 ng/dL = 14.4 pmol/L.
What does high free testosterone mean?
A high result means more unbound, active testosterone is present than expected for your sex and age.
In women — most common causes:
- Polycystic ovary syndrome (PCOS) — the most frequent cause; associated with irregular periods, acne, and excess hair growth (hirsutism)
- Congenital adrenal hyperplasia (CAH) — inherited enzyme deficiency causing excess androgen production
- Ovarian or adrenal tumors — rare but important to exclude when testosterone is markedly elevated
- Exogenous androgen use — testosterone therapy or DHEA supplements
- Cushing's syndrome — excess cortisol associated with androgen overproduction
In men — most common causes:
- Anabolic steroid use — the most common cause of a markedly elevated result
- Testicular or adrenal tumors
- Congenital adrenal hyperplasia
- Low SHBG — reduces binding, increasing the free fraction even when total testosterone is normal
What does low free testosterone mean?
A low result means the active testosterone fraction is below the reference range for your sex and age.
Common causes in men:
- Age-related decline — testosterone falls approximately 1–2% per year after age 30–40
- Hypogonadism — primary (testicular failure) or secondary (pituitary or hypothalamic dysfunction)
- Elevated SHBG — caused by aging, liver disease, hyperthyroidism, or medications
- Obesity, type 2 diabetes, chronic kidney disease
- Medications — glucocorticoids, opioids, certain antifungals
Common causes in women:
- Menopause and age — ovarian testosterone production declines significantly after menopause
- Oral contraceptives — increase SHBG, reducing free testosterone
- Oophorectomy (surgical removal of the ovaries)
- Adrenal insufficiency, hypopituitarism
Free testosterone
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Frequently Asked Questions
What is the difference between direct and calculated free testosterone?
What is free testosterone direct?
What is the normal range for free testosterone in pg/mL?
What is a normal free testosterone level for a woman?
What are normal free testosterone levels for women by age?
What is a normal free testosterone level for my age?
What does "Free Testosterone, Direct Female" mean on a lab report?
What does "WarningLow Free Testosterone (Direct)" mean?
What is the difference between free and total testosterone?
What is pmol/L for free testosterone?
What does high free testosterone mean in females?
What does low free testosterone mean?
All our content is backed by peer-reviewed studies, academic research, and trusted medical sources. We’re committed to accuracy and transparency — see our editorial policy for details.
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Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline
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A critical evaluation of simple methods for the estimation of free testosterone in serum
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Safety and efficacy of testosterone for women: a systematic review and meta-analysis of randomised controlled trial data
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Testosterone, Free, Equilibrium Ultrafiltration With Total Testosterone, LC/MS-MS