Normal Testosterone Levels: Ranges by Age and Sex

Normal testosterone levels span a wide range and differ dramatically between males and females. For adult men, most labs consider a total testosterone of roughly 300 to 1,000 ng/dL (about 10 to 35 nmol/L) to be within the normal window, though that window shifts with age. For adult women, normal total testosterone sits much lower, generally between 15 and 70 ng/dL. Those headline numbers, however, obscure a surprising amount of complexity in how testosterone is produced, measured, and interpreted, and two people with identical numbers on a lab report can have very different clinical pictures.

Total Testosterone, Free Testosterone, and Why the Distinction Matters

When you get a testosterone blood test, the result typically reflects total testosterone, which is the sum of all testosterone floating around in your bloodstream. But most of that hormone is not actually available for your body to use at any given moment. Roughly two-thirds is tightly bound to a protein called sex hormone-binding globulin (SHBG), and about a third is loosely bound to albumin. Only a small fraction, typically around 1 to 3 percent, circulates completely unbound. That unbound portion is called free testosterone, and it can enter cells and trigger biological effects directly. The balance between free and total testosterone is governed by the interplay with these binding proteins, and shifts in SHBG can change free testosterone even when total testosterone stays the same.¹

This matters for a practical reason. Conditions that raise SHBG, like hyperthyroidism or aging, can leave total testosterone looking normal or even elevated while the biologically active free testosterone is low. Conversely, obesity tends to suppress SHBG, which may keep free testosterone relatively stable even as total testosterone drops. Clinicians who rely only on total testosterone can misread the situation in either direction.² Understanding the difference between total and free testosterone is the single most important thing for interpreting any lab result.

How Testosterone Changes Across the Male Lifespan

In boys, testosterone levels are low before puberty and begin rising sharply once the testes start developing. The increases come in stepwise jumps rather than a smooth climb, with notable surges at specific stages of testicular growth.³ By the time a boy’s growth velocity peaks during puberty, morning testosterone has already reached meaningful concentrations.⁴ Levels continue climbing through adolescence and generally peak somewhere in the late teens to early twenties.

After that peak, testosterone begins a gradual, steady decline. Longitudinal data following the same men over years show that total testosterone drops by a small but consistent amount each year, and free testosterone drops right alongside it.⁵ The decline is driven by aging of the entire hormonal axis, from the brain’s signaling centers down to the testosterone-producing cells in the testes.⁶

An interesting twist appears in men over 70. One large study found that total testosterone actually increased marginally with age in this group, while free testosterone continued to decline.⁷ The explanation likely comes back to SHBG, which rises with age and binds more testosterone, keeping total numbers up while the amount that is actually free and active continues to fall. For older men, a total testosterone result that looks reassuring on paper may not reflect what the body is actually working with.

How Testosterone Changes Across the Female Lifespan

Women produce testosterone from two sources in roughly equal measure: the ovaries and the adrenal glands. The ovaries contribute about 25 to 30 percent of circulating testosterone directly, with the adrenals producing a similar share and the rest coming from the conversion of weaker precursor hormones in other tissues.⁸ This dual-source arrangement is important because it means anything that disrupts either the ovaries or the adrenals can shift androgen levels.

In women, testosterone levels decline steeply with age, and the drop is steepest in the younger decades. A study of nearly 600 women found that total testosterone, free testosterone, and other androgens all fell sharply over time, with the pace of decline slowing as women got older.⁹ The same study found no independent effect of menopause itself on androgen levels once age was accounted for, which surprised many clinicians. A separate longitudinal study tracking women through the menopause transition confirmed that total testosterone levels did not change relative to the final menstrual period, though the free androgen index rose because SHBG was falling as estrogen declined.¹⁰

The takeaway is that menopause does not cause a sudden testosterone crash the way it does with estrogen. The decline in women’s androgens is an age-related phenomenon that starts well before the menopausal transition and continues steadily afterward. Women who have their ovaries surgically removed, however, do experience a more abrupt drop because one of the two production sources is eliminated entirely.⁹

Why Your Test Results Depend on When and How Blood Is Drawn

Testosterone is not steady throughout the day. In younger men, levels follow a strong daily rhythm, peaking in the early morning and falling as the day goes on. In men aged 30 to 40, afternoon levels can run 20 to 25 percent lower than morning readings.¹¹ That is a huge swing, enough that a man with normal morning testosterone could test below the lab’s cutoff for “low” if his blood is drawn in the late afternoon. One study found that 17 men who had at least one below-normal result after noon all had normal levels when retested in the morning.¹¹

This daily rhythm flattens out with age. By age 70, the morning-to-afternoon difference shrinks to about 10 percent. Because of this, standard guidelines recommend a morning blood draw for younger men, while men 45 and older can generally get an accurate reading before 2 PM without the result being skewed.¹² Still, average levels drawn between 8 and 11 AM are measurably higher than those drawn in the afternoon or evening, even when controlling for age and body weight.¹³

The Assay Problem

The method your lab uses to measure testosterone also affects the number on your report. The gold-standard technique is liquid chromatography-tandem mass spectrometry. Most clinical labs, however, still use cheaper immunoassay platforms, and these are not always accurate. One head-to-head comparison found that immunoassay results ran about 20 percent lower than the gold-standard method and were poorly correlated with it at concentrations below 100 ng/dL.¹⁴ Another study testing five different immunoassay platforms found that all of them overestimated testosterone in women and children, and none were sufficiently reliable at the low concentrations typical in those groups.¹⁵

The direction of the error depends on the concentration. At high levels, immunoassays may underestimate; at low levels, they tend to overestimate. For a man with testosterone in the typical adult range, the discrepancy may be clinically unimportant. For a woman, a child, or a man suspected of having very low testosterone, the test method can genuinely change the diagnosis. If your doctor is making treatment decisions based on a borderline result, it is worth asking which assay the lab used.

Harmonized Reference Ranges

One reason labs report different “normal” ranges is that they have historically used different measurement platforms and different study populations to set their reference values. A major effort to solve this pooled data from four large cohort studies in the United States and Europe and applied a statistical harmonization procedure. The result showed that much of the apparent variation in testosterone levels between populations was actually measurement variation rather than true biological differences.¹⁶ This work has pushed clinical guidelines toward more standardized cutoffs, though in practice you will still see variation between labs.

What Pushes Your Levels Up or Down

Age is the biggest driver, but it is far from the only one. Several modifiable and non-modifiable factors can shift testosterone substantially enough to change a test result or produce symptoms.

Body Weight

Obesity is one of the most potent suppressors of testosterone in men. Moderate excess weight primarily lowers total testosterone by driving down SHBG through insulin resistance. As obesity becomes more severe, even free testosterone drops because the brain’s hormonal signaling to the testes gets dampened.¹⁷ The relationship is partially reversible: men who lose a meaningful amount of weight often see testosterone rise without any hormone therapy.

Sleep

Sleep deprivation affects testosterone, but the degree depends on how severe the deprivation is. A meta-analysis of studies on partial sleep restriction, the kind where you get four or five hours instead of eight, found no statistically significant drop in testosterone. Total sleep deprivation, staying up all night, did significantly reduce levels.¹⁸ One bad night probably will not change your hormone profile in a lasting way, but chronically skipping sleep could contribute to lower readings over time.

Medications

Certain drugs can meaningfully suppress testosterone. Long-term glucocorticoid therapy, commonly prescribed for autoimmune conditions and chronic inflammation, stands out. In one study of older men on chronic glucocorticoid treatment, average testosterone dropped to about 211 ng/dL compared to roughly 449 ng/dL in matched controls, and higher doses correlated with greater suppression.¹⁹ Opioid pain medications, certain antifungal drugs, and some hormonal treatments can similarly lower levels. If you are on a medication and get an unexpectedly low result, it is worth discussing the drug’s hormonal effects with your doctor before attributing the reading to age or health alone.

Seasonal Shifts

Testosterone also varies with the time of year, though the pattern is not identical everywhere. A large Italian study found total testosterone peaking from August through October and hitting its lowest point in March.²⁰ A study from northern Norway found a somewhat different pattern, with a small peak in February and a more prominent one in October and November, and the lowest levels in the months with the longest daylight and highest temperatures.²¹ The seasonal differences are modest, generally around 5 to 7 percent peak-to-trough, but they add another layer of variability to a single test result.

When Low Testosterone Becomes a Clinical Problem

Having a testosterone result below the lab’s reference range does not automatically mean you need treatment. Many men with low numbers on paper have no symptoms at all, and many men who do have symptoms and receive testosterone therapy see no improvement even when their levels are brought into the normal range.²² Clinical guidelines generally require both a confirmed low lab value (usually two morning readings below 300 ng/dL) and compatible symptoms, things like persistent fatigue, reduced muscle mass, low sex drive, or mood changes, before making a diagnosis of testosterone deficiency.

In women, the picture is even murkier. Low testosterone in women has been linked to reduced libido, low mood, and diminished energy, and this cluster of symptoms has been called the female androgen insufficiency syndrome.²³ The problem is that no reliable threshold exists below which symptoms reliably appear. Standard immunoassays are not accurate enough to measure testosterone precisely in the female range, and the diagnostic criteria are broad enough that they risk overdiagnosis: symptoms like low libido and fatigue are extremely common and have many causes.²⁴ Despite these challenges, some women with very low levels do respond well to carefully dosed testosterone replacement.²⁵

What Elevated Testosterone Signals

For men, unusually high total testosterone sometimes has a straightforward explanation. Hyperthyroidism, for instance, increases the liver’s production of SHBG, which raises total testosterone on a lab test. Free testosterone in these cases is usually normal, meaning the body is not actually experiencing excess androgen activity. Once the thyroid condition is treated, testosterone numbers typically return to baseline.²⁶ Exogenous testosterone use, whether prescribed or otherwise, is another common cause of elevated readings, and it can suppress the body’s own production in the process.

In women, elevated testosterone is more frequently a clinical concern. Polycystic ovary syndrome is the most common endocrine disorder in women of reproductive age, and elevated testosterone, both total and free, is one of its hallmark features and diagnostic criteria. Androstenedione, another androgen, also tends to run high in PCOS. Interestingly, a weaker adrenal androgen called DHEA is typically not elevated in PCOS, which points to the ovaries rather than the adrenals as the primary driver of androgen excess in the condition.²⁷ Other causes of high testosterone in women include congenital adrenal hyperplasia, androgen-secreting tumors (rare), and certain medications.

Testosterone During Pregnancy

Pregnancy pushes a woman’s testosterone to levels she would not experience at any other time in her life. Testosterone rises progressively, with values far above the normal non-pregnant female range. And interestingly, fetal sex appears to influence how high it goes: women carrying male fetuses have been found to have significantly higher testosterone concentrations than those carrying females. One study measured mean levels of about 828 pg/mL in women carrying boys compared to about 597 pg/mL in women carrying girls during early pregnancy, with levels in those carrying male fetuses peaking around weeks 9 to 11 before declining.²⁸

Maternal factors also play a role. In pregnancies with female fetuses, younger maternal age, greater gestational weight gain, and higher amniotic fluid cortisol levels were all independently associated with higher testosterone in the amniotic fluid, together explaining a large portion of the variability.²⁹ The placenta normally acts as a barrier, converting testosterone to estrogen so the fetus is not exposed to excess androgen. When this barrier function is impaired, it may have developmental consequences, which is an active area of research particularly in the context of conditions like PCOS that may have prenatal programming components.

How the Hormonal Control System Works

Testosterone production is regulated by a feedback loop running between the brain and the gonads. The hypothalamus releases a signaling hormone that tells the pituitary gland to produce two hormones of its own: one stimulates the production of sperm in the testes (or egg development in the ovaries), and the other drives testosterone synthesis. When testosterone levels rise high enough, the hypothalamus and pituitary dial back their signals, and production slows. When levels fall, the signals ramp up again.³⁰ This is why exogenous testosterone shuts down the body’s own production: the brain senses high levels and stops asking the testes to make more. It is also why aging affects the system at multiple points simultaneously, since both the brain’s signaling capacity and the testes’ ability to respond decline over time.⁶

In women, the same brain-to-gonad loop operates but is more complex because the ovaries produce testosterone as part of a broader steroid production cascade that also yields estrogen and progesterone. The adrenal glands are regulated by a separate hormonal axis and contribute their own share of androgens, including precursor hormones that peripheral tissues can convert into testosterone.³¹ This dual-axis arrangement means that conditions affecting either the ovaries or the adrenals can independently alter a woman’s androgen profile.

Testosterone Patterns Across Species

It is tempting to assume that testosterone levels in humans are representative of mammals in general, but a survey of hormone levels across the primate order reveals striking diversity. Smaller-bodied New World primates, like marmosets and tamarins, have extremely high circulating levels of testosterone, cortisol, and progesterone compared to Old World primates including humans. Old World species, by contrast, show a more uniform and lower pattern of hormone secretion.³² The differences are large enough that evolutionary lineage, not body size alone, appears to shape baseline hormone levels. This matters for biomedical research that uses primate models: extrapolating hormonal findings from one primate species to another requires caution, and the same principle applies to comparisons between humans and more distantly related animal models.

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