Free Testosterone Test
A free testosterone test measures the unbound portion of testosterone in the blood — the fraction generally described as available to the body's tissues. Clinicians use it to help evaluate the available portion of the hormone, often alongside total testosterone.
About this test
Most testosterone in the blood is bound to proteins — a large share to sex hormone-binding globulin, or SHBG, and some to albumin — while only a small fraction moves freely. A free testosterone test looks specifically at that unbound fraction, the portion typically considered available to interact with tissues. It answers a narrower question than total testosterone, which counts the whole pool of the hormone.
The test is done with a routine blood draw at a patient service center. A phlebotomist collects a sample from a vein, usually in the arm, and sends it to the laboratory. Because testosterone can vary with the time of day, samples are often collected in the morning. Depending on the laboratory, free testosterone may be measured directly or estimated from total testosterone and SHBG, and a clinician reads the result in the context of symptoms, history, and any other markers ordered alongside it.
Who commonly orders it
People who order a free testosterone test are often looking into experiences that can be linked to hormone balance, such as lower libido, fatigue, mood shifts, or changes in strength or body composition. Some choose it when a clinician wants a closer look than the total figure provides, since the amount of carrier protein can shift the total without changing the available fraction to the same degree. Others include it alongside total testosterone to see the whole pool and the available portion together, or to follow a marker a clinician has been tracking. It is frequently chosen when a fuller sense of testosterone status is helpful.
What this test looks at
The free testosterone test focuses on the unbound fraction of the hormone rather than the total amount. Because carrier proteins like SHBG hold most testosterone, the freely circulating portion is small, but it is the part some clinicians want to see directly when the bound and unbound portions may not be tracking together.
It also helps to know what the test does not show: it does not describe the entire pool of testosterone, which is what total testosterone captures. That distinction is exactly why free testosterone is often read together with the total rather than on its own.
How it's often used with other tests
Free testosterone is frequently paired with total testosterone, and sometimes with SHBG, so a clinician can see how the available fraction relates to the whole pool and to the carrier protein that shapes it. Read together, these markers offer a fuller sense of testosterone status than any single one on its own.
Depending on the situation, a clinician may consider additional hormone markers to build a broader picture. The value of the free fraction lies in the context it adds, which is why it is usually interpreted as part of a set rather than in isolation.
What to expect at your visit
No appointment is typically needed. People can visit a patient service center during open hours, and the draw itself is quick — a phlebotomist collects a small sample from a vein in the arm, and most visits wrap up in a few minutes. Because testosterone varies through the day, morning collection is common, so it is worth reading the instructions for the test.
Once the laboratory completes its analysis, results are posted to the account, where they can be reviewed privately and shared with a clinician.
Your results
Results will be emailed securely to you as a PDF.
One-time price · physician order included · no insurance needed
Prefer a fuller panel?
A curated bundle groups this test with the markers clinicians most often review alongside it — often better value than single tests.
Frequently asked questions
What does a free testosterone test measure?+–
It measures the unbound portion of testosterone in the blood — the fraction generally described as available to the body's tissues. This is a smaller, more specific slice than total testosterone, which counts the whole pool.
How is it different from a total testosterone test?+–
Total testosterone counts all the hormone in the blood, including the portion bound to proteins. A free testosterone test measures only the unbound, available fraction. Clinicians often review both together for a fuller picture.
How is the sample collected?+–
Through a routine blood draw at a patient service center. A phlebotomist takes a small sample from a vein in the arm and sends it to the laboratory. Morning collection is common because testosterone varies through the day.
Is free testosterone measured directly?+–
It depends on the laboratory. Some measure it directly, while others estimate it from total testosterone and SHBG. The method can affect interpretation, which is one reason a clinician reads the result in context.
Does this test diagnose low testosterone?+–
No single test diagnoses a condition. A free testosterone result is one piece of information a clinician weighs together with symptoms, age, history, and other markers before drawing any conclusions.
How much is a Testosterone, Free test?+–
$139, paid once at checkout. The price includes the physician's order this test requires and sample collection at any of 2,300+ Quest patient service centers nationwide.