--- title: "Free vs Total Testosterone: What Each Test Measures, Which One You Need, and Why SHBG Decides" type: guide url: "https://www.test-well.com/guides/free-vs-total-testosterone" date_published: 2026-09-28 reviewed_at: 2026-09-28 --- # Free vs Total Testosterone: What Each Test Measures, Which One You Need, and Why SHBG Decides *Total testosterone counts every molecule in the blood; free testosterone counts only the 1–3% that is unbound and able to act. The gap between them is set by a carrier protein called SHBG — which is why a normal total can hide a low free level, and why the best order is usually all three.* > Total testosterone is the standard first test — it is the most accurate and reproducible measurement, and guidelines diagnose low testosterone on two low morning totals. Free testosterone matters when total is borderline or when a condition changes SHBG, the protein that binds most testosterone: obesity, diabetes, aging, thyroid or liver disease, and several medications. In those cases the free level can be low while the total looks normal, or the reverse. Direct free-T immunoassays are unreliable; order total testosterone plus SHBG and let the free value be calculated. ## Recommended tests | Recommended | Type | Price | Why | | --- | --- | --- | --- | | [Testosterone, Total](https://www.test-well.com/tests/testosterone-total) | Test | $33.99 | The guideline first test — morning, fasting, mass-spec method | | [Testosterone, Free & Total + SHBG](https://www.test-well.com/tests/testosterone-free-total-shbg) | Test | $69.99 | Total + SHBG + free — the set that answers the question in one draw | | [Testosterone, Free & Total](https://www.test-well.com/tests/testosterone-free-and-total) | Test | $54.99 | Total with equilibrium-dialysis free testosterone | | [Men's Hormone Panel](https://www.test-well.com/tests/mens-hormone-panel) | Panel (7 tests) | $199.99 | Testosterone with estradiol, LH, FSH and more | All prices are cash-pay plus one $6 lab processing fee per order; physician authorization is included. ## The One-Paragraph Answer About 98% of the testosterone in blood is attached to proteins: roughly half to **sex hormone-binding globulin (SHBG)**, which holds it tightly and keeps it out of cells, and the rest loosely to albumin. Only 1–3% floats free. **Total testosterone** measures all of it. **Free testosterone** estimates just the unbound fraction, and **bioavailable testosterone** adds back the albumin-bound portion tissues can also use. Because SHBG varies so much between people — and rises with age — two men with the same total can have very different free levels. Total is the better measurement; free is the better question, when SHBG is likely to be abnormal. ## What Total Testosterone Measures Total testosterone is reported in ng/dL and is the test every guideline starts with. It is the most standardized and reproducible testosterone measurement, and the Endocrine Society defines low testosterone in men as an unequivocally low total on at least two separate morning samples, together with symptoms. Typical adult male ranges run roughly 264–916 ng/dL by mass spectrometry (Labcorp) or 250–1,100 ng/dL (Quest), with the lower limit anchored around 250–300; adult women fall between about 15 and 70 ng/dL. Method and timing matter. Mass-spectrometry (LC-MS/MS) assays are accurate across the range, including the low values seen in women and hypogonadal men, and are what TestWell's Quest and Labcorp orders use. Testosterone peaks in the early morning and falls through the day, and eating lowers it for a few hours, so the standard draw is between 7 and 10 AM, fasting. Illness, poor sleep and very hard training the day before all push it down temporarily. Full ranges and causes are on the [testosterone reference page](https://www.test-well.com/biomarkers/total-testosterone). ## What Free Testosterone Measures Free testosterone is the fraction not bound to any protein — typically 1–3% of the total, reported in pg/mL or ng/dL. There are three ways to get the number, and they are not equal. **Equilibrium dialysis** is the reference method: accurate, but slow and expensive. **Calculated free testosterone** uses the Vermeulen equation on the measured total testosterone, SHBG and albumin, tracks equilibrium dialysis closely, and is what most laboratories mean by "free testosterone" on a report. **Direct (analog) immunoassays** — the cheapest and most widely sold "free testosterone test" — are the method guidelines specifically advise against, because they are inaccurate and drift with SHBG. The free value is what changes when SHBG changes. High SHBG — with aging, hyperthyroidism, liver disease, low body weight, oral estrogens or anticonvulsants — locks up more testosterone, so free falls while total holds. Low SHBG — with obesity, insulin resistance, type 2 diabetes, hypothyroidism, glucocorticoids or androgens — leaves more free, so a low-normal total can come with an adequate free level. The [SHBG reference page](https://www.test-well.com/biomarkers/shbg) lists the causes, and TestWell's [free testosterone calculator](https://www.test-well.com/tools/free-testosterone-calculator) runs the Vermeulen math on any total, SHBG and albumin. ## Free vs Total Testosterone: Side by Side | | Total testosterone | Free testosterone | | --- | --- | --- | | What it counts | All testosterone — bound and free | The 1–3% not bound to protein | | Guideline role | First test; diagnosis requires two low morning totals | Second test when total is borderline or SHBG is likely abnormal | | Best method | LC-MS/MS (mass spectrometry) | Equilibrium dialysis, or calculated from total + SHBG + albumin | | Method to avoid | Immunoassay at low levels (women, children) | Direct/analog immunoassay — inaccurate | | Moved by SHBG? | Somewhat — total tracks SHBG loosely | Strongly — this is the point of measuring it | | Typical adult male range | ~264–916 or 250–1,100 ng/dL (lab-dependent) | Roughly 50–200 pg/mL; 1.5–3% of total | | Draw | 7–10 AM, fasting, when well | Same sample as total | ## Which Should You Order? - **Symptoms of low testosterone and no prior testing:** [total testosterone](https://www.test-well.com/tests/testosterone-total), morning and fasting. If it comes back clearly low or clearly normal, you have your answer (repeat a low one on a second morning before concluding anything). - **You want one draw that settles it whatever the total shows:** [total + free + SHBG](https://www.test-well.com/tests/testosterone-free-total-shbg). It adds the two numbers that make a borderline total interpretable, so you do not need a second visit. - **Obesity, type 2 diabetes, thyroid or liver disease, age over 50, or medications that move SHBG** (oral estrogen, anticonvulsants, glucocorticoids, opioids): total + SHBG at minimum — this is exactly the group where total alone misleads, and guidelines call for free testosterone here. - **Already on testosterone therapy:** total testosterone, timed relative to your dose as your prescriber directs, usually with estradiol and a CBC; free adds little on therapy unless SHBG is abnormal. - **A woman being evaluated for PCOS, hirsutism or acne:** total testosterone by mass spectrometry with SHBG; the free androgen index or calculated free testosterone is more informative than total alone because low SHBG amplifies modest androgen excess. What to skip: a "free testosterone" test sold on its own by direct immunoassay. It is the one testosterone measurement guidelines say not to rely on. ## How to Read Them Together | Total | SHBG | Calculated free | Usual meaning | | --- | --- | --- | --- | | Low (twice, morning) | Normal | Low | Hypogonadism is likely; LH and FSH locate the cause (testes vs pituitary), then prolactin and iron studies as indicated. | | Normal | High | Low | The classic hidden case — total looks fine but little is available. Look for the SHBG driver (aging, thyroid, liver, low weight, medications) and treat symptoms on the free value with a clinician. | | Low-normal | Low | Normal | Common in obesity and insulin resistance; free testosterone is adequate, and weight and metabolic health are the lever rather than hormone therapy. | | High | Low | High | In women: supports androgen excess (PCOS, or an adrenal/ovarian source if very high or rapid). In men: exogenous testosterone or androgens, or rarely a tumor. | | Normal | Normal | Normal | Testosterone is not the explanation for the symptoms; look at sleep, thyroid, iron, mood, medications and other hormones. | Rules that make any of this readable: draw between 7 and 10 AM, fasting; repeat a low total on a separate morning before acting; avoid testing during illness, after a night of poor sleep or within a day of very hard training; and use the same laboratory for results you intend to compare. ## What to Do With the Result Two low morning totals with symptoms is the point at which a clinician evaluates for hypogonadism: LH and FSH to distinguish a testicular from a pituitary cause, prolactin, iron studies, a medication review, and — in secondary hypogonadism — sometimes pituitary imaging. Testosterone therapy is a decision made after that work-up, not on a single number, because it suppresses fertility and can mask a treatable cause. A low free level with a normal total is handled the same way, with the SHBG driver addressed where possible. A normal pair with persistent symptoms redirects the search rather than ending it. All of these are routine morning draws at Quest and Labcorp, orderable through TestWell with physician review; results post within a few business days with the laboratory's ranges and, on the SHBG panel, the calculated free value. ## Frequently asked questions ### Is free or total testosterone more important? Total testosterone is the more accurate measurement and the one guidelines diagnose on — two low morning totals with symptoms. Free testosterone is the more relevant question when SHBG is abnormal, because it shows how much hormone is actually available to tissues. In practice the best order is total plus SHBG, with free calculated from them. ### Can total testosterone be normal but free testosterone low? Yes — it is the classic hidden case. High SHBG (from aging, hyperthyroidism, liver disease, low body weight or medications such as oral estrogen and anticonvulsants) binds more testosterone, so the total reads normal while the free fraction is low and symptoms are real. Measuring SHBG with the total exposes it. ### Why do guidelines warn against direct free testosterone tests? Direct (analog) immunoassays for free testosterone are inaccurate and drift with SHBG, so they can be misleading in exactly the people who need the test. Guidelines recommend equilibrium dialysis or a calculation from accurately measured total testosterone, SHBG and albumin — which is what 'calculated free testosterone' on a lab report means. ### What is bioavailable testosterone? Free testosterone plus the portion loosely bound to albumin, which tissues can also use. It is typically 20–40% of the total. Like free testosterone it is calculated from total, SHBG and albumin, and it is an alternative way of expressing how much hormone is actually available. ### When should testosterone be drawn? Between 7 and 10 AM, fasting, on a day you are well and not sleep-deprived or recovering from very hard training. Testosterone peaks early in the morning and falls through the day, and meals lower it for a few hours. A low result should be repeated on a second morning before anything is concluded. ### Do women need free or total testosterone? Total testosterone by mass spectrometry is the accurate first test in women, because immunoassays are unreliable at female levels. SHBG is often added so the free androgen index or calculated free testosterone can be read — in PCOS, low SHBG amplifies modest androgen excess, so the free value tells more than the total alone. ## Sources - [Bhasin S, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab 2018;103:1715–1744.](https://doi.org/10.1210/jc.2018-00229) - [Vermeulen A, Verdonck L, Kaufman JM. A critical evaluation of simple methods for the estimation of free testosterone in serum. J Clin Endocrinol Metab 1999;84:3666–3672.](https://doi.org/10.1210/jcem.84.10.6079) - [Goldman AL, et al. A Reappraisal of Testosterone's Binding in Circulation. Endocr Rev 2017;38:302–324.](https://doi.org/10.1210/er.2017-00025) - [MedlinePlus (NIH) — Testosterone Levels Test](https://medlineplus.gov/lab-tests/testosterone-levels-test/) --- Medically reviewed by Youmna DiStefano, MD (Medical Reviewer, TestWell); last reviewed 2026-09-28. Review policy: https://www.test-well.com/reviewers/youmna-distefano-md Canonical page: https://www.test-well.com/guides/free-vs-total-testosterone Machine-readable catalog: https://www.test-well.com/api/catalog.json · MCP server: https://www.test-well.com/mcp · Overview for agents: https://www.test-well.com/llms.txt Prices are cash-pay, in USD, and include physician authorization; every order adds one flat $6 lab processing fee. Educational content is not a diagnosis — discuss results with a clinician.