You can check your testosterone levels with a simple blood test, typically ordered by your doctor or purchased through an at-home testing kit. The most common version measures total testosterone, and for the most accurate reading, the blood draw should happen in the morning between 7 and 10 a.m., when testosterone peaks during its daily cycle. If results come back below 300 ng/dL, that’s the widely used threshold for diagnosing low testosterone in men.
Total, Free, and Bioavailable Testosterone
Most of the testosterone circulating in your blood is bound to proteins, primarily one called sex hormone-binding globulin (SHBG). A smaller portion is loosely attached to another protein called albumin, and a tiny fraction floats freely. These distinctions matter because only the unbound testosterone, plus the loosely attached portion, is readily available for your body to actually use. That usable portion is called “bioavailable” testosterone.
A total testosterone test measures everything: bound, loosely bound, and free. For most people, this is all that’s needed to get a clear picture. Total testosterone levels for adult men generally fall between 193 and 824 ng/dL, though the reference range can vary slightly between labs.
Free and bioavailable testosterone tests become important when total testosterone looks normal but you still have symptoms, or when something is throwing off your SHBG levels. Several conditions and medications can raise or lower SHBG, which shifts how much testosterone is actually available to your tissues. For example, you could have a normal total testosterone number but high SHBG, meaning less testosterone is free for your body to use. In that scenario, your doctor would order a free or bioavailable test to get the real story. Bioavailable testosterone is generally considered the more useful of the two follow-up tests.
Why Morning Testing Matters
Testosterone follows a predictable daily rhythm. Levels climb during the night, peak between about 7 and 10 a.m., and gradually fall throughout the day, hitting their lowest point in the evening. Current clinical recommendations call for a blood draw between 8 and 9 a.m. to minimize the effect of this natural fluctuation. Testing in the afternoon could give you a result that looks low simply because of timing, not because anything is actually wrong.
Your provider may also ask you to fast for several hours beforehand, drinking only water. This isn’t always required, but it helps ensure other blood markers tested alongside testosterone aren’t skewed by a recent meal.
Lab Draws vs. At-Home Kits
A standard blood draw from a vein (venipuncture) remains the gold standard. The sample is large enough, typically 2 to 4 teaspoons, to give a lab plenty of material for accurate analysis.
At-home kits generally come in two forms: finger-prick blood tests and saliva tests. Finger-prick kits are convenient, but they produce significantly more variable results. Research published in Clinical Chemistry found that capillary samples can show three to eight times more variability than venous blood for biomarkers including total testosterone. The problems are mostly mechanical: squeezing a fingertip to get blood damages red blood cells, dilutes the sample with fluid from surrounding tissue, and increases the risk of clotting before the sample reaches the lab. Failure rates are higher too, because people often don’t collect enough blood or the sample degrades before processing.
That doesn’t mean at-home kits are useless. They can work as a screening tool, giving you a rough sense of where your levels land. But if a finger-prick test flags low testosterone, best practice is to confirm the result with a standard venous draw before making any clinical decisions. Some at-home services now offer venous collection kits that a mobile phlebotomist performs at your home, which largely solves the accuracy gap.
What Your Results Mean
The American Urological Association uses 300 ng/dL as the diagnostic cutoff for low testosterone in men. Below that level, combined with symptoms like fatigue, low libido, reduced muscle mass, or mood changes, a diagnosis of testosterone deficiency is reasonable. But a single low reading isn’t enough. Doctors typically require at least two separate morning blood draws showing low levels before confirming a diagnosis, because testosterone can fluctuate day to day based on sleep, stress, illness, and other factors.
Results above 300 ng/dL don’t automatically mean everything is fine. This is where SHBG becomes relevant. If your SHBG is unusually high, a “normal” total testosterone of, say, 450 ng/dL might actually mean very little free testosterone is reaching your tissues. Your doctor can order SHBG alongside total testosterone to estimate your bioavailable levels and get a more complete picture.
It’s also normal for testosterone to decline with age. A 55-year-old will typically have lower levels than a 25-year-old, and that alone doesn’t indicate a problem. Context matters: your symptoms, your age, your overall health, and sometimes additional hormone tests like LH and FSH (which help pinpoint whether the issue originates in the testes or the brain’s signaling system) all factor into interpretation.
When Women Should Test Testosterone
Women produce testosterone too, in much smaller amounts, and testing is most commonly done when symptoms suggest levels are too high. Signs that might prompt a test include unusual facial or body hair growth, thinning hair on the head in a pattern similar to male baldness, persistent acne, voice changes, irregular or absent periods, and difficulty getting pregnant. These symptoms can point to conditions like polycystic ovarian syndrome (PCOS), which involves elevated androgens.
For women being treated for high testosterone, total testosterone alone can be misleading. Bioavailable or free testosterone is typically monitored alongside total levels to make sure treatment is actually bringing the active hormone into a normal range, not just shifting the total number on paper.
How to Get the Test
The most straightforward route is asking your primary care doctor. If you describe symptoms consistent with a hormonal issue, most providers will order a morning total testosterone test, often bundled with SHBG and sometimes LH and FSH. Insurance typically covers the test when it’s ordered for a medical reason.
If you prefer to skip the office visit, several direct-to-consumer lab services let you order a testosterone panel online, then visit a local lab for a venous blood draw. You pay out of pocket, usually between $50 and $150 depending on how many hormones are included. Results generally come back within a few days. This approach gives you lab-grade accuracy without needing a prescription, though you’ll still want a clinician to help interpret the results if anything looks off.
Whichever route you choose, the key steps are the same: test in the early morning, fast if instructed, use a venous blood draw for the most reliable numbers, and plan on repeating the test if the first result is abnormal.