A testosterone level of 400 ng/dL means different things at 25 and at 55. The number matters, but so does the context: how it was measured, what time of day, what the free testosterone fraction looks like, and what symptoms, if any, are present.

Understanding testosterone ranges by age starts with accepting that “normal” is a wide band, not a precise target.

The Reference Ranges by Decade

The Endocrine Society sets the normal range for total testosterone in adult men as approximately 300 to 1,000 ng/dL. That range does not change with age in clinical guidelines, but average levels do decline across decades.

Data from the Massachusetts Male Aging Study and subsequent longitudinal research puts average total testosterone across age groups roughly as follows:

  • Ages 20-29: Average around 600-700 ng/dL, range 300-1,100 ng/dL
  • Ages 30-39: Average around 550-650 ng/dL, some decline beginning
  • Ages 40-49: Average around 470-580 ng/dL
  • Ages 50-59: Average around 400-530 ng/dL
  • Ages 60+: Average around 350-490 ng/dL, with wider individual variation

After age 30, testosterone declines at roughly 1 to 2 percent per year on average. This is gradual enough that most men do not notice it year to year, but by age 60 the cumulative decline can be substantial.

These are averages derived from population studies. An individual man at 65 can have testosterone above 700 ng/dL. Another man at 30 can have testosterone below 300 ng/dL. The population distribution is wide.

Total vs. Free Testosterone

The number on a standard testosterone test is total testosterone, which includes both bound and free hormone.

Most testosterone in the blood is bound to proteins. About 40-50% binds to albumin, and about 40-50% binds to sex hormone-binding globulin (SHBG). The remaining 2-3% circulates as free testosterone, unattached to any protein.

Only free testosterone can enter cells and bind to androgen receptors. Bound testosterone is biologically inactive, essentially a reservoir.

This distinction matters clinically because SHBG levels change with age, typically increasing. Higher SHBG means a larger fraction of total testosterone is bound, leaving less biologically active free testosterone even when total levels look acceptable.

A man with a total testosterone of 450 ng/dL and high SHBG might have less free testosterone than a man with a total of 380 ng/dL and low SHBG. Total testosterone alone does not tell the whole story.

Free testosterone reference ranges are approximately 9-30 ng/dL, though laboratories vary in how they measure and report this.

What Affects Testosterone Levels

Several modifiable factors influence where your testosterone sits within that broad range.

Sleep is one of the strongest. Most testosterone is produced during deep sleep, particularly in the early morning hours. A 2011 study published in JAMA found that restricting healthy young men to five hours of sleep for one week reduced their daytime testosterone by 10 to 15 percent. Poor sleep is also associated with lower luteinizing hormone, the signal from the pituitary that triggers testosterone production.

Body fat, especially visceral fat, suppresses testosterone through two mechanisms. Fat cells contain aromatase, an enzyme that converts testosterone to estrogen. Higher body fat means more aromatase activity and lower net testosterone. Visceral fat also impairs the hypothalamic-pituitary-gonadal (HPG) axis signaling chain.

Chronic stress elevates cortisol, which competes with testosterone at the receptor level and signals the hypothalamus to reduce LH production. Cortisol and testosterone exist in a generally inverse relationship.

Alcohol, particularly heavy consumption, suppresses testosterone production at the testicular level and increases aromatase activity. Moderate consumption has less clear effects, but chronic heavy drinking reliably lowers testosterone.

Exercise, particularly resistance training, acutely raises testosterone and, over time, is associated with higher baseline levels compared to sedentary individuals. Endurance training in very high volumes can have the opposite effect.

When Should You Test

Testing makes sense if you have symptoms that could plausibly be related to low testosterone: persistent fatigue, reduced libido, difficulty building or maintaining muscle, mood changes, or cognitive fogginess that you cannot attribute to another cause.

Testing also makes sense as a baseline before making changes to training, sleep, or other variables you think might be suppressing levels.

For accuracy, testosterone should be tested in the morning, ideally between 7 and 10 am, when levels peak. A single test is not definitive. Testosterone fluctuates day to day, and labs report results slightly differently. Two morning tests, at least a week apart, give a more reliable picture.

A complete initial panel should include total testosterone, free testosterone (or SHBG to calculate it), LH, FSH, and often a complete blood count. LH and FSH help distinguish between primary hypogonadism (the testes are not producing enough) and secondary hypogonadism (the pituitary is not signaling properly). The distinction matters for treatment.

When the Numbers Warrant Action

The Endocrine Society clinical guidelines recommend testosterone therapy for men with confirmed hypogonadism: consistently low testosterone on two separate morning measurements, combined with symptoms.

Low testosterone on a lab test without symptoms is not typically grounds for treatment. Symptoms without lab confirmation are also not grounds for treatment alone. The combination of both is when intervention conversations become appropriate.

A level below 300 ng/dL with symptoms is the general clinical threshold, though individual providers and patients weigh the evidence differently. The conversation with a doctor about whether to treat, and how to treat, should include a full review of your specific numbers, symptoms, and health history.

For more on what symptoms low testosterone actually produces, see 9 Signs of Low Testosterone That Men Frequently Dismiss. If you are already considering treatment, Testosterone Injections vs. Gel: Which Delivery Method Is Better? covers what the evidence shows about each approach.