If you’re trying to get a straight answer on testosterone levels by age, here’s what the evidence actually shows. If you’ve had a testosterone test, you’ve probably stared at the result wondering one thing: is that good? It’s a harder question to answer than it should be, because “normal” testosterone covers a famously wide range, labs report it differently, and what’s typical for your age isn’t necessarily what’s optimal.
This guide gives you the clearest picture available, a testosterone-by-age chart for men, what the reference numbers actually mean, why “low normal” is a genuine grey zone, and why your symptoms matter as much as the number itself.
This guide breaks down testosterone levels by age: what the evidence says, what is worth doing, and what is worth skipping.
How Testosterone Is Measured
Testosterone is measured with a blood test, reported in nanograms per deciliter (ng/dL) in the US (or nmol/L in much of the rest of the world; roughly, 1 nmol/L ≈ 28.8 ng/dL).
Two things make interpretation tricky:
- Reference ranges vary by lab and by the testing method used. There’s no single universal cutoff.
- Testosterone follows a daily rhythm, peaking in the morning. That’s why tests should be done before about 10 AM, and why a single afternoon reading can be misleadingly low.
The harmonised CDC reference range for adult men aged 19–39 is 264–916 ng/dL, a span so wide it tells you how much natural variation exists between healthy men.
Average Total and Free Testosterone Levels by Age
| Age | Typical total testosterone (ng/dL) | Total testosterone (nmol/L) | Approx. free testosterone (ng/dL)* |
|---|---|---|---|
| Teens (post-puberty) | ~300–1,200 | ~10.4–41.6 | ~6–24 |
| 20s (peak ~18–20) | ~250–1,100 | ~8.7–38.1 | ~5–22 |
| 30s | ~250–1,000 | ~8.7–34.7 | ~5–20 |
| 40s | ~250–900 | ~8.7–31.2 | ~5–18 |
| 50s | ~230–850 | ~8.0–29.5 | ~4–17 |
| 60s | ~200–800 | ~6.9–27.7 | ~4–16 |
| 70s+ | ~200–750 | ~6.9–26.0 | ~4–15 |
Treat these as typical population ranges, not personal targets — individual variation is large. *Free testosterone is estimated as roughly 1.5–2% of total and is assay-dependent, so use your own lab’s range. To convert units, 1 ng/dL ≈ 0.0347 nmol/L.
Free testosterone is only about 1.5–2% of your total, but it is the unbound fraction that actually reaches your tissues, which is why it often tracks symptoms better than the total number. Confused by the difference? Read our full breakdown of free vs total testosterone and why free T matters more.
The clear pattern: testosterone peaks around age 18–20, then declines slowly, roughly 1% per year from the 30s onward. The bottom of the “normal” range drifts down with each decade, which is part of why what counts as concerning shifts with context.
What is a normal testosterone level for a young man?
Broad lab ranges lump a 25-year-old in with a 65-year-old, which hides a lot. A 2022 analysis in The Journal of Urology looked specifically at healthy men aged 20–44 and reported age-specific “normal” (middle-third) ranges — and they sit well above the old 300 ng/dL cutoff:
| Age | “Normal” total testosterone (ng/dL) | Total testosterone (nmol/L) |
|---|---|---|
| 20–24 | 409–558 | 14.2–19.4 |
| 25–29 | 413–575 | 14.3–19.9 |
| 30–34 | 359–498 | 12.4–17.3 |
| 35–39 | 352–478 | 12.2–16.6 |
| 40–44 | 350–473 | 12.1–16.4 |
So a 30-year-old reading 320 ng/dL is technically “in range” by the old cutoff, yet sits below the normal middle for his age. That gap is also why some men with “normal” results still feel the symptoms of low testosterone — fatigue, low drive, weight gain, and low mood can appear in the 300–400 ng/dL range even when a lab calls the number normal.
What Counts as “Low”?
This is where it gets genuinely contested:
- The American Urological Association and many providers define low testosterone as below 300 ng/dL.
- Some labs report down to 264 ng/dL as still within the normal range.
- The Endocrine Society suggests evaluating men with symptoms when levels are below 264 ng/dL on repeat testing, while noting that men in the 264–400 ng/dL range with significant symptoms fall into a clinical grey zone where individual assessment matters.
- Some researchers argue the healthiest men sit in the 400–600 ng/dL range, and that “low normal” isn’t truly optimal for everyone.
The honest takeaway: there’s no single magic number. A reading of 350 ng/dL might be fine for one man and leave another symptomatic. Which is exactly why doctors don’t treat the number in isolation.
Why the Number Alone Isn’t Enough
Two men can have identical total testosterone and feel completely different. Here’s why:
Free vs total testosterone. Most of your testosterone is bound to proteins (mainly SHBG and albumin) and isn’t biologically active. Only the small “free” fraction is actually available to your tissues. A man with normal total testosterone but high SHBG can have low free testosterone, and feel the symptoms, despite a normal-looking total. We explain this fully in our guide to free vs total testosterone (see also what is SHBG).
Symptoms. A number is only meaningful alongside how you feel. The clinical definition of low testosterone requires both a low level and symptoms, fatigue, low libido, lost muscle, low mood. We cover these in detail in our article on the signs of low testosterone (see also when to see a doctor about low testosterone).
So when you get your result, don’t fixate on the single total number. Ask about your free testosterone and SHBG too, and weigh it against your actual symptoms.
What Affects Your Levels (Beyond Age)
Age is only one factor. Several others can push your testosterone down, and many are reversible:
- Excess body fat, especially belly fat, which converts testosterone to estrogen
- Poor sleep and untreated sleep apnea
- Chronic stress and elevated cortisol
- Excessive alcohol
- Sedentary lifestyle and lack of resistance training
- Certain medications and medical conditions
This is encouraging news: a low-ish reading isn’t necessarily a life sentence of decline. Addressing weight, sleep, stress, and activity often raises levels meaningfully. We cover the practical levers in our guides on foods that boost testosterone and exercises to increase testosterone.
FAQ: Testosterone Levels by Age
What is a normal testosterone level for a 40-year-old man?
Typically somewhere in the range of roughly 250–900 ng/dL, though the healthy and optimal point within that is individual. Many clinicians consider below 300 ng/dL low, particularly with symptoms.
What testosterone level is considered low?
Commonly below 300 ng/dL (AUA), with some labs using 264 ng/dL as the lower limit. The Endocrine Society treats 264–400 ng/dL with symptoms as a grey zone needing individual assessment.
When should I get my testosterone tested?
In the morning, before about 10 AM, when levels peak. Diagnosis usually requires two separate low morning readings.
Does testosterone really drop 1% a year?
A decline of roughly 1% per year from the 30s is commonly cited. The rate varies between individuals, and lifestyle factors can accelerate or offset it.
Is “low normal” testosterone a problem?
It can be, if you have symptoms. Some researchers argue the healthiest range is 400–600 ng/dL, so a “low normal” reading with bothersome symptoms is worth discussing with a doctor rather than dismissing.
The Bottom Line on Testosterone levels by age
The bottom line on testosterone levels by age: Testosterone peaks in your late teens and declines gradually with age, with the “normal” range being famously wide, roughly 264–916 ng/dL for younger men. Below 300 ng/dL is commonly considered low, but the number alone never tells the whole story: your free testosterone, your SHBG, and above all your symptoms determine what your level actually means for you. If you’re testing, do it in the morning, ask for the full picture rather than just total testosterone, and remember that many causes of low levels, weight, sleep, stress, are within your control.
This article is for informational purposes only and does not constitute medical advice. Consult a qualified healthcare professional to interpret your results.
Sources
- The Journal of Urology (2022): What Is a Normal Testosterone Level for Young Men? Rethinking the 300 ng/dL Cutoff for Men 20–44
- Cleveland Clinic: Testosterone, What It Is, Function, Levels and Imbalances
- Testosterone Levels by Age: Normal Levels for Males and Females, Healthline
- Testosterone Levels by Age Chart: Normal vs Optimal (2026), Highland Longevity
- What Is a Normal Testosterone Level for Your Age, Medichecks
- Evaluation and Management of Testosterone Deficiency, AUA Guideline
