Testosterone levels by age differ less than many charts suggest. In a harmonized analysis of 6,933 non-obese men, median total testosterone was 531 ng/dL (18.4 nmol/L) at ages 19 to 39 and 477 ng/dL (16.6 nmol/L) in every decade from 50 to 79, while the lower end of the range fell with age. Those figures compare different men at different ages; they do not show how one man's level changes over time.
That is useful context, not a verdict. Your result is read against your own laboratory's reference interval, in its units, with the time and circumstances of the blood draw. This guide gives the age chart in both units, shows where each figure comes from and explains why timing and repeat testing matter.
What is a normal testosterone level for a man?
A normal total testosterone level for a healthy young man is about 264 to 916 ng/dL, or 9.2 to 31.8 nmol/L. That is the harmonized reference range in the Endocrine Society's 2018 testosterone guideline for healthy, non-obese men aged 19 to 39, using the 2.5th to 97.5th percentiles.
A reference interval is the band that holds most results, often the middle 90 to 95%, from a chosen reference population. It describes what is common, not what is ideal.
Harmonized means each cohort's results were calibrated to one reference method. That step matters because assays disagree. The same Endocrine Society guideline reports that when 1,133 laboratories using 14 different assays measured one quality control sample from a man with hypogonadism, results ranged from 45 to 365 ng/dL (1.6 to 12.7 nmol/L). The harmonization study by Travison and colleagues calibrated four US and European cohorts to a CDC reference method before setting its ranges.
Your laboratory's interval and a guideline threshold are different tools. The American Urological Association (AUA) guideline gives the example of a 250 ng/dL result that a laboratory may mark as normal but that falls below the guideline's 300 ng/dL cut-off.
How do ng/dL and nmol/L compare in the US, UK and Australia?
US guidance is written in ng/dL; UK and Australian guidance uses nmol/L. To convert, multiply ng/dL by 0.0347, the factor given in a review of the endocrinology of the aging male. To go the other way, divide nmol/L by 0.0347, which is the same as multiplying by about 28.8.
So 300 ng/dL is about 10.4 nmol/L, and 12 nmol/L is about 346 ng/dL.
| Country | Unit in guidance | Example threshold or interval | Timing advice |
|---|---|---|---|
| US | ng/dL | AUA: below 300 ng/dL supports a diagnosis of low testosterone | Two early morning tests on separate occasions |
| UK | nmol/L | BSSM: above 12 nmol/L does not require treatment | Between 7 a.m. and 11 a.m., on at least two occasions |
| Australia | nmol/L | ESA: 10.4 to 30.1 nmol/L by mass spectrometry in men aged 21 to 35 with normal reproductive function | Between 8 a.m. and 10 a.m., with at least two measurements |
The UK row comes from the British Society for Sexual Medicine (BSSM) guideline and the Australian row from the Endocrine Society of Australia (ESA) position statement. Every one of these bodies also requires symptoms or signs before calling a level deficient.
Testosterone levels by age chart for men
This chart shows the model-based percentiles for non-obese men (body mass index under 30) in the Travison harmonization study. Each figure came from a single morning sample, converted to nmol/L with the 0.0347 factor.
| Age (years) | 5th percentile | Median | 95th percentile |
|---|---|---|---|
| 19 to 39 | 304 ng/dL (10.5 nmol/L) | 531 ng/dL (18.4 nmol/L) | 850 ng/dL (29.5 nmol/L) |
| 40 to 49 | 273 ng/dL (9.5 nmol/L) | 481 ng/dL (16.7 nmol/L) | 839 ng/dL (29.1 nmol/L) |
| 50 to 59 | 256 ng/dL (8.9 nmol/L) | 477 ng/dL (16.6 nmol/L) | 839 ng/dL (29.1 nmol/L) |
| 60 to 69 | 254 ng/dL (8.8 nmol/L) | 477 ng/dL (16.6 nmol/L) | 839 ng/dL (29.1 nmol/L) |
| 70 to 79 | 252 ng/dL (8.7 nmol/L) | 477 ng/dL (16.6 nmol/L) | 839 ng/dL (29.1 nmol/L) |
| 80 to 99 | 218 ng/dL (7.6 nmol/L) | 476 ng/dL (16.5 nmol/L) | 839 ng/dL (29.1 nmol/L) |
A percentile is the point below which that share of men fell, so 5% of non-obese men in each age band had a result below the first column. These are population descriptions, not targets.
Weight shifts the chart down. When the study included men with obesity, the median for ages 19 to 39 was 507 ng/dL (17.6 nmol/L) rather than 531 ng/dL.
Does testosterone drop with age?
Testosterone does drop with age on average, but slowly and not in every man. The aging review cited above reports that longitudinal studies show an average fall in total testosterone of 1 to 2% a year. Free testosterone falls faster because sex hormone-binding globulin (SHBG), a blood protein that binds testosterone, rises with age. The same review notes that testosterone can stay stable or even rise in some men.
The ESA position statement describes declines in the order of 0.5 to 2% a year in reportedly healthy men. It adds that there are no convincing data that healthy aging necessarily lowers testosterone to the point of clinical deficiency, and that obesity, disease burden and medicines may explain a substantial part of the fall.
The ESA also states that age alone is not an indication for testosterone treatment. Our guide to free versus total testosterone explains both measures.
What testosterone level is considered low?
A total testosterone below 300 ng/dL (about 10.4 nmol/L) is the AUA's cut-off for low testosterone, but only after two early morning tests on separate occasions. The AUA also states that a clinical diagnosis of testosterone deficiency needs low levels combined with symptoms or signs.
Other bodies draw the line slightly differently. The Endocrine Society uses its harmonized lower limit of 264 ng/dL (9.2 nmol/L). The BSSM uses 12 nmol/L as the level above which treatment is not required.
The Endocrine Society also recommends against routine screening of men in the general population. A low number without symptoms is not a diagnosis. For the symptom side of the question, read low testosterone symptoms in men.
Why does the time of the testosterone test matter?
Testosterone follows a daily rhythm, so a late afternoon result can look low when the morning result is not. The AUA guideline reports that in men aged 30 to 40, values at 4 p.m. were 20 to 25% lower than at 8 a.m., while men aged 70 showed only about a 10% difference.
The Endocrine Society advises a fasting morning sample because glucose and food intake suppress testosterone. It also notes that 30% of men with an initial low result have a normal result on repeat. The AUA, by contrast, judges the evidence on food weak and does not insist on fasting. The ESA advises sampling between 8 a.m. and 10 a.m., notes that fasting gives higher levels, and suggests testing shortly after waking for shift workers.
Sleep counts too. In a small study of 10 young men, a week of five-hour nights lowered daytime testosterone by 10% to 15%. If your sleep is short, our article on how much deep sleep you need covers what to look at first.
How to read your own testosterone result
1. Keep the units with the number.
A result of 12 means nothing until you know whether it is nmol/L or ng/dL.
2. Use the interval printed on your report.
Compare your number with your laboratory's range first. Do not judge a UK or Australian result against a US chart without converting it.
3. Check which test was run.
Total and free testosterone are different measurements. Note whether free testosterone was measured or calculated.
4. Record the time and the circumstances.
Write down the time of the draw, whether you had eaten, and any recent illness, night shift or short sleep. The AUA warns that acute illness can falsely lower results.
5. Ask how it was measured.
The ESA prefers mass spectrometry where available because many immunoassays show method-dependent bias. The AUA recommends using the same laboratory and method for repeat tests.
6. Treat one low result as a question.
The guidelines above generally ask for at least two morning measurements before calling testosterone low.
When should you see a doctor about your testosterone level?
See a doctor when you have symptoms that fit low testosterone, or a result flagged as low, and want to know whether they connect. In the US that usually starts with a primary care physician; in the UK and Australia, with your GP.
Bring the full report with units, interval, time and method. If a supplement ad started the search, read how to check testosterone booster claims first. If you might want children, read TRT and fertility before any treatment is discussed.
Frequently asked questions
What is a normal testosterone level for a man?
For healthy, non-obese men aged 19 to 39, the Endocrine Society's harmonized reference range is 264 to 916 ng/dL, or 9.2 to 31.8 nmol/L. Your own laboratory sets its own interval, so compare your result with the range printed on your report and confirm the units before drawing any conclusion.
Does testosterone drop with age?
On average, yes, but slowly. Longitudinal studies show total testosterone falling by about 1 to 2% a year, and the Endocrine Society of Australia notes that obesity, illness and medicines may explain a substantial part of it. The harmonized study's modeled medians were similar across older age groups, but it compared different men rather than following individuals.
What testosterone level is considered low?
The American Urological Association uses a total testosterone below 300 ng/dL, about 10.4 nmol/L, confirmed on two early morning tests. The Endocrine Society's harmonized lower limit is 264 ng/dL. The guidelines cited here also require symptoms or signs, so a single low number is not a diagnosis of testosterone deficiency.
What is a normal testosterone level in nmol/L?
The Endocrine Society's harmonized range for healthy young men is 9.2 to 31.8 nmol/L. The Endocrine Society of Australia cites 10.4 to 30.1 nmol/L by mass spectrometry in men aged 21 to 35 with normal reproductive function. To convert ng/dL to nmol/L, multiply by 0.0347.
What time of day should testosterone be tested?
Early morning. The American Urological Association reports that 4 p.m. results in men aged 30 to 40 were 20 to 25% lower than at 8 a.m. UK guidance suggests 7 a.m. to 11 a.m. and Australian guidance 8 a.m. to 10 a.m., with a repeat test before any diagnosis.
The short version
In population data, median testosterone in non-obese men is similar across older age groups, while the lower end of the range drifts down. Those are comparisons between men, not a forecast for yours. Read your result in its own units, against your own laboratory's interval, and with the time of the draw in mind. Guidelines ask for two morning tests plus symptoms before calling testosterone low.
This article is general education, not medical advice. It does not replace your own physician.
