Most medical organizations consider a total testosterone level between 300 and 1,000 ng/dL normal for adult men, with 300 ng/dL being the most widely used cutoff for “low.” But that single number doesn’t tell the whole story. What counts as healthy depends on your age, the time of day your blood is drawn, and whether you’re actually experiencing symptoms.
The Standard Reference Range
The American Urological Association sets the low-testosterone threshold at 300 ng/dL, and this is the number most doctors in the U.S. use when deciding whether to investigate further. Other organizations draw the line differently. The Endocrine Society uses 264 ng/dL, while several European and international groups set their cutoffs higher, between 345 and 350 ng/dL. The upper end of normal falls around 916 ng/dL based on large population studies.
These cutoffs matter because they determine who gets diagnosed and who doesn’t. A man with a level of 280 ng/dL would be flagged as low by the AUA’s standard but considered normal by the American Association of Clinical Endocrinologists, which uses a 200 ng/dL threshold. If your result lands in that gray zone, your symptoms become the deciding factor.
How Testosterone Changes With Age
Testosterone peaks in early adulthood and declines gradually from there. Men in their early 20s typically have levels in the 400 to 560 ng/dL range (middle of the pack), while men in their late 30s and early 40s tend to fall between 350 and 475 ng/dL. The decline isn’t dramatic year to year, but over decades it adds up.
The ranges widen significantly as men get older:
- Age 40–49: 252–916 ng/dL
- Age 50–59: 215–878 ng/dL
- Age 60–69: 196–859 ng/dL
- Age 70–79: 156–819 ng/dL
Notice that even in their 70s, some men maintain levels above 800 ng/dL, while others dip below 200. This huge variation is why comparing yourself to a population average is less useful than tracking your own symptoms alongside your numbers. A 2023 study in The Journal of Urology actually argued that the 300 ng/dL cutoff is too low for younger men. The researchers found that age-specific cutoffs for men under 45 ranged from 350 to 413 ng/dL, suggesting that a 25-year-old at 310 ng/dL may genuinely be low even though he clears the standard threshold.
Total vs. Free Testosterone
When your doctor orders a testosterone test, the standard result is “total testosterone,” which measures everything circulating in your blood. But most of that testosterone is bound to proteins, particularly one called sex hormone-binding globulin (SHBG), and can’t actively do its job in tissues. Only about 2–3% circulates freely, and this “free testosterone” is what your body can actually use.
The normal range for free testosterone is roughly 50 to 200 pg/mL. There’s also a middle category called “bioavailable testosterone,” which includes both free testosterone and testosterone loosely bound to a protein called albumin. For men aged 20 to 69, the bioavailable range is 110 to 400 ng/dL.
Free testosterone matters most when your total number looks normal but you still have symptoms. SHBG levels rise with age, meaning a 55-year-old man could have a total testosterone of 450 ng/dL but very little of it available to his body. If your doctor suspects this mismatch, they’ll order free testosterone or a bioavailable testosterone panel alongside SHBG.
When Symptoms Start Appearing
Numbers on a lab report don’t always match how you feel. Some men function perfectly well at 350 ng/dL; others feel noticeably off at 400. That said, research has identified a symptom threshold. A study of men over 40 found that five specific complaints clustered most strongly with levels at or below 300 ng/dL: decreased sex drive, low energy, reduced strength or endurance, decreased ability to play sports, and falling asleep after dinner.
The testosterone levels at which these symptoms became noticeably more common ranged from 320 to 375 ng/dL. In other words, men don’t typically wake up one day with sudden symptoms the moment they cross below 300. The transition is gradual, and many men start feeling the effects while they’re still technically in the “normal” range. This is one reason some international guidelines set their cutoffs closer to 350 ng/dL rather than 300.
Why Testing Timing Matters
Testosterone follows a daily rhythm. Levels peak between 7:00 and 10:00 in the morning, drop through the afternoon, hit their lowest point in the evening, and begin rising again overnight. Current guidelines recommend drawing blood between 8:00 and 9:00 a.m. to capture your peak and minimize the effect of this natural fluctuation.
A test taken at 3:00 p.m. could easily read 100 to 150 ng/dL lower than one taken at 8:00 a.m. in the same person. If your result comes back borderline low and the blood was drawn in the afternoon, the number may not reflect your actual baseline. Levels also vary from day to day based on sleep, stress, illness, and alcohol intake, which is why guidelines call for at least two separate morning blood draws before making any diagnosis.
Risks of Levels That Are Too High
While most men searching this topic are worried about low testosterone, excessively high levels carry their own problems. This is primarily a concern with testosterone therapy or performance-enhancing use rather than natural production. Artificially elevated testosterone can cause low sperm counts and shrunken testicles (counterintuitively), increased risk of blood clots, heart muscle damage, prostate enlargement, liver problems, fluid retention, high blood pressure, elevated cholesterol, and severe acne. Sleep disruption, mood swings, and impaired judgment have also been reported.
Your body has a feedback system that naturally prevents testosterone from climbing too high on its own. When the brain detects sufficient levels, it signals the testes to slow production. External testosterone overrides this system, which is why supraphysiologic doses create risks that normal production does not.
What Your Number Actually Means
A single testosterone reading is a snapshot, not a diagnosis. If your level comes back below 300 ng/dL on two separate morning tests and you’re experiencing symptoms like persistent fatigue, reduced sex drive, or loss of muscle mass, that combination points toward a real deficiency worth addressing. If your level is 350 and you feel fine, there’s no clinical reason to chase a higher number.
Context also matters. Obesity, poor sleep, chronic stress, and certain medications (especially opioids and corticosteroids) can all suppress testosterone temporarily. In those cases, addressing the underlying issue often brings levels back up without any hormonal treatment. If you’re getting tested, make sure it’s a fasting morning blood draw, and ask for free testosterone and SHBG alongside the total number to get the full picture.