Curated by Nelson Vergel | ExcelMale.com | Updated April 2026
If your lab report shows free testosterone and you're unsure whether the number is normal for your age, you're asking the right question. Free testosterone is the small fraction (roughly 2 to 3 percent) that isn't bound to SHBG or albumin, which makes it the portion actually available to your cells. For many men, it tells a more honest story than total testosterone alone.
The problem: "normal" depends heavily on age, and most lab reports still compare every man to a single one-size-fits-all cutoff. This guide gives you age-stratified ranges drawn from the two strongest datasets published to date (Walravens et al., 2025, JCEM; Jasuja et al., 2023, Andrology), plus the practical context to interpret your own result rather than relying on a generic cutoff.
• Why free testosterone falls with age and how to read the decline.
• How to convert between pmol/L and pg/mL and run your own numbers.
• When free testosterone is more useful than total testosterone.
• When a result justifies a TRT conversation.
The reference range for men aged 18 to 39 with a BMI under 30 was 184 to 749 pmol/L (roughly 53 to 216 pg/mL). From there, free testosterone declines steadily with each decade.
Age-Stratified Free Testosterone Reference Ranges (Healthy, Non-Obese Men)
Source: Walravens et al., JCEM, 2025. Values are 2.5th to 97.5th percentile. To convert pmol/L to pg/mL, divide by 3.467.
A separate US dataset from Jasuja et al. (2023) reported the overall reference interval for healthy non-obese men 19 and up as 66 to 309 pg/mL (229 to 1,072 pmol/L), with the 19 to 39 subgroup at 120 to 368 pg/mL. Both datasets broadly agree: a healthy young man's free testosterone sits between roughly 150 and 700 pmol/L, with the midpoint near 400.
• At or below the lower bound for your age: flagged as low. Paired with symptoms, this supports a hypogonadism diagnosis.
• Lower third of your age range: borderline. Symptoms matter enormously here. Many men in this zone feel genuinely undermedicated despite "within range" labs.
• Middle to upper third: typical for age. If you feel well, you probably are.
• Above the upper bound: rare without exogenous testosterone. Can occur on TRT, with certain supplements, or with very low SHBG.
Example: a 35-year-old at 160 pmol/L is at the low end of normal for his age (range 173 to 652). Technically in range, but if he has classic low-T symptoms, that context matters. A 65-year-old at 110 pmol/L is within his own age group's range (104 to 402), even though the same number would be flagged low for a 35-year-old. This is the case for age-stratified interpretation.
• Rising SHBG. SHBG climbs about 0.65 nmol/L per year. More SHBG binds more testosterone, shrinking the free fraction even when total T looks stable. This is why total testosterone can read "normal" in older men while symptoms suggest otherwise.
• Testicular decline. As free T falls, LH rises: the pituitary pushes harder for output, and the testes don't fully keep up. Researchers call this age-related testicular functional impairment, distinct from benign aging.
• Equilibrium dialysis (ED LC-MS/MS). The gold standard. Costs more and takes longer. LabCorp test 500726 is the specific order; Quest offers its own ED panel.
• Calculated (Vermeulen formula). Uses total testosterone, SHBG, and albumin to estimate the free fraction. Adequate for most men when SHBG and albumin are normal. The ExcelMale Hormone Calculator Suite runs this for you in seconds.
• Direct analog immunoassay. Unreliable in men. Results are often misleading. Avoid when possible.
There is also the TruT calculator (a newer Multistep Dynamic Binding Model), which has its own validated target range of 164 to 314 pg/mL for men on TRT. It tends to produce higher numbers than Vermeulen. Both calculators are reasonable; the reference range depends on which one you use.
• Total testosterone looks fine but symptoms are classic low T.
• You're on a medication known to alter SHBG (some anticonvulsants, high-dose thyroid, certain antifungals, oral estrogens).
• You're over 60 and your clinician is applying a young-man cutoff.
In those situations, a measured free T can change the diagnosis and the treatment. For everyone else, a good calculated free T from the Vermeulen formula is enough.
Total Testosterone Reference Ranges by Age (Typical Lab Ranges for Men)
Typical US laboratory reference intervals for men (non-TRT) based on LabCorp and Quest 2024 to 2025 data; the 19 to 39 range reflects Travison et al., JCEM 2017 (Framingham, EMAS, Osteoporotic Fractures in Men cohorts).
Notice that the bottom of total testosterone doesn't move dramatically with age (~264 at 19 to 39, ~156 at 70+), but free testosterone falls far more steeply because SHBG keeps climbing. This is exactly why total T alone often misleads men over 50.
Symptoms of low free testosterone (low libido, weaker morning erections, persistent fatigue, loss of muscle, brain fog, flat mood) are covered in depth in the ExcelMale low-T symptom guide. A useful anchor point from Liu et al. 2017: late-onset hypogonadism symptoms increase sharply below about 77 pg/mL (268 pmol/L) calculated free testosterone.
• TruT-validated target: 164 to 314 pg/mL (roughly 570 to 1,090 pmol/L).
• Vermeulen-calculated: most men in our community feel best in the upper quartile of the 19 to 39 reference range, typically 20 to 35 ng/dL (200 to 350 pg/mL).
One nuance for older men: if you're 70 and your free T on therapy is 250 pmol/L, you're well above the median for your age group and within the normal range for younger men. That's a different clinical conversation than a 35-year-old at the same number. Work with a provider who understands this distinction.
• What is the lowest free testosterone blood level for low T symptoms? - Community discussion of symptom thresholds at different free T values.
• Sex Hormone Binding Globulin (SHBG): Is It Good or Bad? - The lever that moves your free T number. Essential companion reading.
• TruT calculator - what is the range? - Comparing Vermeulen-calculated free T against the TruT method.
• Spreadsheet for Calculating Free T & E2 - Member-built tool converting total T, SHBG, and albumin into free and bioavailable T plus free E2.
• ExcelMale Hormone Calculator Suite - Full TRT toolkit: free T (Vermeulen), dose calculator, HCG reconstitution, E2/DHT predictor.
• How to Get a Testosterone Prescription Online: A Complete Guide for Men - What labs (including free T) your clinic should be ordering before starting TRT.
• DiscountedLabs: Affordable Free and Total Testosterone Testing - Order your own free T (equilibrium dialysis) and total T panel without a doctor's visit.
2. Jasuja R, Pencina KM, Peng L, Bhasin S. Reference intervals for free testosterone in adult men measured using a standardized equilibrium dialysis procedure. Andrology, 2023;11(1):125-133. https://onlinelibrary.wiley.com/doi/10.1111/andr.13310
3. Bhasin S, Brito JP, Cunningham GR, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. Journal of Clinical Endocrinology and Metabolism, 2018;103(5):1715-1744. https://academic.oup.com/jcem/article/103/5/1715/4939465
4. Travison TG, Vesper HW, Orwoll E, et al. Harmonized Reference Ranges for Circulating Testosterone Levels in Men of Four Cohort Studies in the United States and Europe. Journal of Clinical Endocrinology and Metabolism, 2017;102(4):1161-1173. https://pmc.ncbi.nlm.nih.gov/articles/PMC5460736/
5. Vermeulen A, Verdonck L, Kaufman JM. A Critical Evaluation of Simple Methods for the Estimation of Free Testosterone in Serum. Journal of Clinical Endocrinology and Metabolism, 1999;84(10):3666-3672. https://academic.oup.com/jcem/article/84/10/3666/2864820
6. Liu PY, Beilin J, Meier C, et al. Age-related changes in serum testosterone and sex hormone binding globulin in Australian men. Journal of Clinical Endocrinology and Metabolism, 2017;102(7):2562-2571. https://pubmed.ncbi.nlm.nih.gov/28510716/
7. Goldman AL, Bhasin S, Wu FCW, Krishna M, Matsumoto AM, Jasuja R. A Reappraisal of Testosterone's Binding in Circulation: Physiological and Clinical Implications. Endocrine Reviews, 2017;38(4):302-324. https://pubmed.ncbi.nlm.nih.gov/28673039/
8. Mulhall JP, Trost LW, Brannigan RE, et al. Evaluation and Management of Testosterone Deficiency: AUA Guideline. Journal of Urology, 2018;200(2):423-432. https://www.auajournals.org/doi/10.1016/j.juro.2018.03.115
Don't compare yourself to a 25-year-old unless you are one. Use the age-stratified table above. If your calculated result looks unusual or your symptoms don't match the numbers, request equilibrium dialysis (LabCorp 500726). And always pair the number with what you feel, because labs diagnose dysfunction only in context.
Next steps: the complete SHBG guide pairs naturally with this article, and the Hormone Calculator Suite lets you run your own numbers. To order labs directly, use DiscountedLabs.com.
If your lab report shows free testosterone and you're unsure whether the number is normal for your age, you're asking the right question. Free testosterone is the small fraction (roughly 2 to 3 percent) that isn't bound to SHBG or albumin, which makes it the portion actually available to your cells. For many men, it tells a more honest story than total testosterone alone.
The problem: "normal" depends heavily on age, and most lab reports still compare every man to a single one-size-fits-all cutoff. This guide gives you age-stratified ranges drawn from the two strongest datasets published to date (Walravens et al., 2025, JCEM; Jasuja et al., 2023, Andrology), plus the practical context to interpret your own result rather than relying on a generic cutoff.
What You Will Learn
• Normal free testosterone ranges for men 18 through 80+.• Why free testosterone falls with age and how to read the decline.
• How to convert between pmol/L and pg/mL and run your own numbers.
• When free testosterone is more useful than total testosterone.
• When a result justifies a TRT conversation.
Key Takeaways ▪ Free testosterone is the ~2 to 3 percent of total testosterone not bound to SHBG or albumin, so it's the portion actually available to tissues. ▪ The best current reference range for healthy, non-obese men aged 18 to 39 is 184 to 749 pmol/L (Walravens et al., 2025). ▪ Free testosterone declines by about 4.5 pmol/L per year, driven mostly by a steady rise in SHBG. ▪ In the Walravens dataset, 76.3 percent of men 80+ fell below the young-adult reference range. Applying a 25-year-old's cutoff to an 80-year-old overdiagnoses hypogonadism. ▪ For routine TRT monitoring, a Vermeulen-calculated free T is usually adequate. When SHBG is abnormal or symptoms persist despite normal labs, request equilibrium dialysis (LabCorp test 500726). ▪ Symptoms, not a single lab value, guide treatment. Two morning draws below the reference range plus consistent symptoms is the standard for a hypogonadism diagnosis. |
What Is the Normal Free Testosterone Level for Men by Age?
The most defensible age-stratified ranges come from the Walravens et al. (2025) study in the Journal of Clinical Endocrinology and Metabolism. Researchers measured free testosterone directly in 1,202 healthy Caucasian men aged 18 to 86 using equilibrium dialysis with LC-MS/MS, the gold-standard method.The reference range for men aged 18 to 39 with a BMI under 30 was 184 to 749 pmol/L (roughly 53 to 216 pg/mL). From there, free testosterone declines steadily with each decade.
Age-Stratified Free Testosterone Reference Ranges (Healthy, Non-Obese Men)
Age Group | Free Testosterone (pmol/L) | Free Testosterone (pg/mL) | Median (pmol/L) |
18 to 29 | 239 to 877 | 6.9 to 25.3 | ~460 |
30 to 39 | 173 to 652 | 5.0 to 18.8 | ~360 |
40 to 49 | 146 to 557 | 4.2 to 16.1 | ~300 |
50 to 59 | 128 to 475 | 3.7 to 13.7 | ~255 |
60 to 69 | 104 to 402 | 3.0 to 11.6 | ~210 |
70 to 79 | 72 to 315 | 2.1 to 9.1 | ~165 |
80 and up | 49 to 250 | 1.4 to 7.2 | ~115 |
A separate US dataset from Jasuja et al. (2023) reported the overall reference interval for healthy non-obese men 19 and up as 66 to 309 pg/mL (229 to 1,072 pmol/L), with the 19 to 39 subgroup at 120 to 368 pg/mL. Both datasets broadly agree: a healthy young man's free testosterone sits between roughly 150 and 700 pmol/L, with the midpoint near 400.
How Do I Know If My Free Testosterone Is Low for My Age?
Compare your result to the row matching your age. A few practical guardrails:• At or below the lower bound for your age: flagged as low. Paired with symptoms, this supports a hypogonadism diagnosis.
• Lower third of your age range: borderline. Symptoms matter enormously here. Many men in this zone feel genuinely undermedicated despite "within range" labs.
• Middle to upper third: typical for age. If you feel well, you probably are.
• Above the upper bound: rare without exogenous testosterone. Can occur on TRT, with certain supplements, or with very low SHBG.
Example: a 35-year-old at 160 pmol/L is at the low end of normal for his age (range 173 to 652). Technically in range, but if he has classic low-T symptoms, that context matters. A 65-year-old at 110 pmol/L is within his own age group's range (104 to 402), even though the same number would be flagged low for a 35-year-old. This is the case for age-stratified interpretation.
Why Does Free Testosterone Decline with Age?
The decline is real and measurable. In the Walravens dataset, free testosterone falls an average of 4.5 pmol/L per year. By age 70, the median is roughly half of what it was at 25. Two things drive this:• Rising SHBG. SHBG climbs about 0.65 nmol/L per year. More SHBG binds more testosterone, shrinking the free fraction even when total T looks stable. This is why total testosterone can read "normal" in older men while symptoms suggest otherwise.
• Testicular decline. As free T falls, LH rises: the pituitary pushes harder for output, and the testes don't fully keep up. Researchers call this age-related testicular functional impairment, distinct from benign aging.
Does That Mean Most Older Men Are Hypogonadal?
In the Walravens study, 76.3 percent of men over 80 fell below the lower limit of the 18 to 39 reference range. That doesn't mean three-quarters of 80-year-olds need TRT; it reflects how we set thresholds. The researchers recommend age-stratified Z-scores (compare a man to his peers) rather than T-scores (compare him to a 25-year-old) when diagnosing pathology versus normal aging. In practice, this means working with a men's-health-literate provider who reads numbers in context.
How Is Free Testosterone Measured and Which Method Should I Ask For?
Three methods dominate, and they are not equivalent:• Equilibrium dialysis (ED LC-MS/MS). The gold standard. Costs more and takes longer. LabCorp test 500726 is the specific order; Quest offers its own ED panel.
• Calculated (Vermeulen formula). Uses total testosterone, SHBG, and albumin to estimate the free fraction. Adequate for most men when SHBG and albumin are normal. The ExcelMale Hormone Calculator Suite runs this for you in seconds.
• Direct analog immunoassay. Unreliable in men. Results are often misleading. Avoid when possible.
There is also the TruT calculator (a newer Multistep Dynamic Binding Model), which has its own validated target range of 164 to 314 pg/mL for men on TRT. It tends to produce higher numbers than Vermeulen. Both calculators are reasonable; the reference range depends on which one you use.
When Should I Ask for Equilibrium Dialysis?
• SHBG is below ~20 nmol/L or above ~60 nmol/L.• Total testosterone looks fine but symptoms are classic low T.
• You're on a medication known to alter SHBG (some anticonvulsants, high-dose thyroid, certain antifungals, oral estrogens).
• You're over 60 and your clinician is applying a young-man cutoff.
In those situations, a measured free T can change the diagnosis and the treatment. For everyone else, a good calculated free T from the Vermeulen formula is enough.
What About Total Testosterone by Age?
Most labs still lead with total testosterone. Here are the typical US reference intervals:Total Testosterone Reference Ranges by Age (Typical Lab Ranges for Men)
Age Group | Total Testosterone (ng/dL) | Total Testosterone (nmol/L) |
19 to 39 | 264 to 916 | 9.2 to 31.8 |
40 to 49 | 252 to 880 | 8.7 to 30.5 |
50 to 59 | 215 to 878 | 7.5 to 30.5 |
60 to 69 | 196 to 859 | 6.8 to 29.8 |
70 and up | 156 to 820 | 5.4 to 28.5 |
Notice that the bottom of total testosterone doesn't move dramatically with age (~264 at 19 to 39, ~156 at 70+), but free testosterone falls far more steeply because SHBG keeps climbing. This is exactly why total T alone often misleads men over 50.
Should I Use Total or Free Testosterone to Decide on TRT?
Both. Most experienced men's-health clinicians use total testosterone as the initial screen (cheap, widely available, validated against outcomes), then free testosterone to refine the picture, especially when total T is in the gray zone (200 to 350 ng/dL), symptoms persist despite normal total T, SHBG is unusually low or high, or age is over 50. This mirrors Endocrine Society guidance.Symptoms of low free testosterone (low libido, weaker morning erections, persistent fatigue, loss of muscle, brain fog, flat mood) are covered in depth in the ExcelMale low-T symptom guide. A useful anchor point from Liu et al. 2017: late-onset hypogonadism symptoms increase sharply below about 77 pg/mL (268 pmol/L) calculated free testosterone.
What Is the Optimal Free Testosterone Target for Men on TRT?
The goal on TRT isn't "maximize free T." It's feeling well without side effects (elevated hematocrit, high estradiol, acne, sleep disruption). Two reference points are useful:• TruT-validated target: 164 to 314 pg/mL (roughly 570 to 1,090 pmol/L).
• Vermeulen-calculated: most men in our community feel best in the upper quartile of the 19 to 39 reference range, typically 20 to 35 ng/dL (200 to 350 pg/mL).
One nuance for older men: if you're 70 and your free T on therapy is 250 pmol/L, you're well above the median for your age group and within the normal range for younger men. That's a different clinical conversation than a 35-year-old at the same number. Work with a provider who understands this distinction.
Frequently Asked Questions
What is the average free testosterone by age?
Based on Walravens 2025, the median is roughly 460 pmol/L at 18 to 29, falling to ~210 pmol/L at 60 to 69 and ~115 pmol/L in men 80+. Individual variation within each decade is wide; your own number matters more than the decade average.What pg/mL free testosterone is considered low?
Below about 65 to 77 pg/mL (225 to 268 pmol/L) by equilibrium dialysis or Vermeulen-calculated. Below that, symptomatic hypogonadism becomes substantially more likely. Ranges vary by lab, so always check the reference interval on your report.How do I convert pmol/L to pg/mL?
Divide pmol/L by 3.467. Example: 450 pmol/L divided by 3.467 is about 130 pg/mL. Multiply pg/mL by 3.467 to go the other direction.Does BMI affect the ranges?
Yes. Compared with a BMI of 22, Walravens found free T roughly 14 percent lower at BMI 30 and 22 percent lower at BMI 35. Obesity lowers SHBG, which partially preserves free T even when total T drops, so measuring free T is often more accurate in heavier men. Full context is in the ExcelMale SHBG guide.Does the time of day matter for the test?
Yes. Testosterone peaks in the early morning. Diagnostic draws should happen before 10 AM, fasting preferred, and two separate morning draws are the standard. For men on TRT, trough levels immediately before the next injection are the most standardized measurement.Related ExcelMale Forum Discussions
• Why Your Testosterone Test Might Be Lying to You: 5 Surprising Truths from the New Gold Standard Study - Deep dive into the Walravens 2025 study and what it means for your lab interpretation.• What is the lowest free testosterone blood level for low T symptoms? - Community discussion of symptom thresholds at different free T values.
• Sex Hormone Binding Globulin (SHBG): Is It Good or Bad? - The lever that moves your free T number. Essential companion reading.
• TruT calculator - what is the range? - Comparing Vermeulen-calculated free T against the TruT method.
• Spreadsheet for Calculating Free T & E2 - Member-built tool converting total T, SHBG, and albumin into free and bioavailable T plus free E2.
• ExcelMale Hormone Calculator Suite - Full TRT toolkit: free T (Vermeulen), dose calculator, HCG reconstitution, E2/DHT predictor.
• How to Get a Testosterone Prescription Online: A Complete Guide for Men - What labs (including free T) your clinic should be ordering before starting TRT.
• DiscountedLabs: Affordable Free and Total Testosterone Testing - Order your own free T (equilibrium dialysis) and total T panel without a doctor's visit.
Key References
1. Walravens J, Snaterse G, Narinx N, et al. Age-Stratified Reference Ranges for Directly Measured Serum Free Testosterone in Community-Dwelling and Healthy Men. Journal of Clinical Endocrinology and Metabolism, 2025; dgaf507. https://doi.org/10.1210/clinem/dgaf5072. Jasuja R, Pencina KM, Peng L, Bhasin S. Reference intervals for free testosterone in adult men measured using a standardized equilibrium dialysis procedure. Andrology, 2023;11(1):125-133. https://onlinelibrary.wiley.com/doi/10.1111/andr.13310
3. Bhasin S, Brito JP, Cunningham GR, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. Journal of Clinical Endocrinology and Metabolism, 2018;103(5):1715-1744. https://academic.oup.com/jcem/article/103/5/1715/4939465
4. Travison TG, Vesper HW, Orwoll E, et al. Harmonized Reference Ranges for Circulating Testosterone Levels in Men of Four Cohort Studies in the United States and Europe. Journal of Clinical Endocrinology and Metabolism, 2017;102(4):1161-1173. https://pmc.ncbi.nlm.nih.gov/articles/PMC5460736/
5. Vermeulen A, Verdonck L, Kaufman JM. A Critical Evaluation of Simple Methods for the Estimation of Free Testosterone in Serum. Journal of Clinical Endocrinology and Metabolism, 1999;84(10):3666-3672. https://academic.oup.com/jcem/article/84/10/3666/2864820
6. Liu PY, Beilin J, Meier C, et al. Age-related changes in serum testosterone and sex hormone binding globulin in Australian men. Journal of Clinical Endocrinology and Metabolism, 2017;102(7):2562-2571. https://pubmed.ncbi.nlm.nih.gov/28510716/
7. Goldman AL, Bhasin S, Wu FCW, Krishna M, Matsumoto AM, Jasuja R. A Reappraisal of Testosterone's Binding in Circulation: Physiological and Clinical Implications. Endocrine Reviews, 2017;38(4):302-324. https://pubmed.ncbi.nlm.nih.gov/28673039/
8. Mulhall JP, Trost LW, Brannigan RE, et al. Evaluation and Management of Testosterone Deficiency: AUA Guideline. Journal of Urology, 2018;200(2):423-432. https://www.auajournals.org/doi/10.1016/j.juro.2018.03.115
Conclusion and Next Steps
Free testosterone is the single most useful hormone value for understanding how much androgen your tissues actually see. Total testosterone is easier to measure and still the starting point, but it can mislead as you age because SHBG rises year after year.Don't compare yourself to a 25-year-old unless you are one. Use the age-stratified table above. If your calculated result looks unusual or your symptoms don't match the numbers, request equilibrium dialysis (LabCorp 500726). And always pair the number with what you feel, because labs diagnose dysfunction only in context.
Next steps: the complete SHBG guide pairs naturally with this article, and the Hormone Calculator Suite lets you run your own numbers. To order labs directly, use DiscountedLabs.com.
