For adult men (18 and older), normal total testosterone falls between 193 and 824 ng/dL. For adult women, normal levels are below 40 ng/dL. These are the standard reference ranges, but where you fall within them matters less than you might think. Your symptoms, the time of day your blood was drawn, and even which lab processed your sample all influence what your number actually means.
Normal Testosterone Ranges by Age
Testosterone changes dramatically across a lifetime. In boys, levels stay below 12 ng/dL until around age 6, then begin climbing slowly. Puberty brings a massive surge, with levels potentially reaching as high as 830 ng/dL by age 11 to 15. By the late teens, the adult range of 102 to 1,010 ng/dL is established, and from 18 onward, the accepted reference range narrows to 193 to 824 ng/dL.
For women, levels follow a different trajectory. Girls stay below 25 ng/dL until puberty, when levels can rise to around 79 ng/dL. Adult women typically measure below 40 ng/dL. That number isn’t trivial, though. Testosterone plays a role in bone density, muscle maintenance, and energy in women too. Conditions like polycystic ovary syndrome (PCOS) can push women’s levels well above the normal range, sometimes doubling or tripling expected values in younger women. Interestingly, women with PCOS see their testosterone drop by roughly 50% between their early 40s and late 40s, partially resolving on its own before menopause, though levels often remain higher than in women without the condition.
The 300 ng/dL Threshold
If you’re a man wondering whether your levels are “low,” the number that matters most clinically is 300 ng/dL. The American Urological Association uses this as the cutoff for diagnosing testosterone deficiency. Below 300, measured on at least two separate morning blood draws from the same lab, is the formal definition of low testosterone. That two-test requirement exists because a single reading can be misleading. Your levels fluctuate day to day based on sleep, stress, illness, and other factors.
Being just above 300 doesn’t automatically mean everything is fine, and being just below doesn’t guarantee you’ll have symptoms. The threshold is a clinical tool, not a perfect dividing line. Some men at 350 ng/dL feel terrible, while others at 280 feel fine. Context matters.
Total, Free, and Bioavailable Testosterone
Most blood tests measure total testosterone, which includes all the testosterone in your blood, both the portion your body can readily use and the portion bound to proteins. Only about 2 to 3% of your testosterone circulates freely, unattached to anything. The rest is locked up by proteins, primarily one called sex hormone-binding globulin (SHBG) and another called albumin. This binding is actually protective. It prevents your body from burning through its testosterone supply too quickly.
Free testosterone is the small unbound fraction your muscles and bones can access immediately. Bioavailable testosterone is a slightly broader measure that includes free testosterone plus the portion loosely attached to albumin (which your body can still access fairly easily). If your total testosterone comes back normal but you still have symptoms, your provider may order a free or bioavailable testosterone test. Some men have normal total levels but high SHBG, which traps more testosterone and leaves less of it available for the body to use.
Why Morning Testing Matters
Testosterone follows a daily rhythm, peaking in the early morning and dropping as the day goes on. In men aged 30 to 40, levels measured at 4 p.m. are 20 to 25% lower than levels at 8 a.m. Flipped around, morning readings run 30 to 35% higher than afternoon readings. That’s a massive swing. A man who tests at 350 ng/dL in the morning might register below 260 by late afternoon, crossing the clinical threshold for deficiency based purely on timing.
This is why guidelines recommend drawing blood in the morning, ideally before 10 a.m. The pattern holds in older men too, though the daily swing tends to flatten somewhat with age. If your test was drawn in the afternoon or evening, an unexpectedly low result may simply reflect the time of day rather than a genuine deficiency.
Your Lab’s Range May Differ
One of the most confusing parts of reading your results is that different labs report different reference ranges. Your lab report might say “normal” is 250 to 1,100 ng/dL while another lab uses 193 to 824 ng/dL. This isn’t a rounding error. Surveys of over 1,000 clinical laboratories have found that the highest and lowest reported values for a single testosterone sample can differ by more than double. Even labs running the same type of test show significant variation in accuracy and precision.
The variation is especially pronounced at lower concentrations, the exact range where a diagnosis of deficiency hangs in the balance. At levels below 100 ng/dL (common in women and men with severe deficiency), results from different testing methods can swing by as much as 40% in either direction. The CDC launched a standardization project in 2007 to make testosterone measurements comparable across labs, methods, and time, but variability still exists. The practical takeaway: always retest at the same lab using the same method if you’re tracking your levels over time. Comparing a result from one lab to a result from another is unreliable.
Signs Your Levels May Be Low
Low testosterone doesn’t announce itself with a single obvious symptom. The early signs are nonspecific: reduced sex drive, lower energy, and depressed mood. These overlap with dozens of other conditions, which is why a blood test is necessary to confirm the cause. Over time, untreated low testosterone in men can lead to erectile dysfunction, reduced muscle mass, loss of body and facial hair, and difficulty with fertility.
In younger males, low testosterone can delay or stall puberty, affecting voice deepening, genital development, and muscle growth. In women, symptoms of low testosterone are less well-defined but can include persistent fatigue, reduced libido, and decreased bone density.
Risks of Levels That Are Too High
Most conversations focus on low testosterone, but levels that are too high carry their own health risks. A large genetic study published in eLife found that higher testosterone in men was associated with a 51% increased risk of prostate cancer, a 49% increased risk of hair loss, and a 17% increased risk of hypertension. Higher levels also correlated with thickened blood (elevated hematocrit), lower HDL (“good”) cholesterol, and an increased risk of benign prostate enlargement. These risks are particularly relevant for men using testosterone therapy, where levels can climb above the natural range if dosing isn’t carefully monitored.
Naturally elevated testosterone in women, most commonly from PCOS, brings concerns including irregular periods, acne, excess facial or body hair, and long-term risks for cardiovascular disease and endometrial cancer. Women with PCOS who maintain elevated testosterone into their later years appear to carry a higher cardiovascular risk than women whose levels normalize.
What Affects Your Results
Beyond time of day and lab variability, several factors can push your results higher or lower without reflecting a true change in your hormonal health. Poor sleep, especially chronic sleep deprivation, suppresses testosterone. Acute illness or high physical stress temporarily lowers levels. Obesity is one of the strongest modifiable factors: excess body fat increases SHBG and promotes conversion of testosterone to estrogen, often resulting in lower free testosterone. Certain medications, including opioids and some corticosteroids, can also suppress production.
Age itself plays a role. Men’s testosterone declines gradually starting around age 30, typically by about 1% per year. A 60-year-old man at 400 ng/dL is in a very different position than a 25-year-old at the same level. When interpreting your results, the number on the lab report is the starting point, not the full picture.