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Testosterone levels by age: check your result against UK ranges
Type in a total testosterone result in nmol/L or ng/dL. See where it sits against the British Society for Sexual Medicine’s 12 nmol/L line and a harmonised range for adult men, and what changes with age.
Quick answer
In the UK, total testosterone above 12 nmol/L is not low for an adult man. Below 12 nmol/L on two morning tests, with symptoms, usually needs treatment, and below 8 nmol/L is clearly low. The same lines apply at every adult age.
- Free testosterone falls by about 3 pmol/L a year after 40 on average; obesity lowers testosterone more than age.
- A harmonised range for non-obese men aged 19 to 39 runs from 9.2 to 31.8 nmol/L (264 to 916 ng/dL).
- Test in the morning and repeat a low result before acting on it.
Enter a total testosterone result to see it against UK thresholds.
The UK thresholds, explained
| Total testosterone | In ng/dL | What UK guidance says |
|---|---|---|
| Below 12 nmol/L | Below 346 | With symptoms, on two morning tests, usually needs treatment. So does calculated free testosterone below 0.225 nmol/L.[1] |
| 8 to 14 nmol/L | 231 to 404 | Men with symptoms may be offered a trial of treatment for at least six months.[1] |
| Above 12 nmol/L | Above 346 | Does not need treatment, by total testosterone alone.[1] |
| 9.2 to 31.8 nmol/L | 264 to 916 | Harmonised 2.5th to 97.5th centiles for non-obese men aged 19 to 39, across four cohorts.[2] |
What happens to testosterone with age
In the European Male Ageing Study of 3,200 men aged 40 to 79, free testosterone was about 3.1 pmol/L lower for each extra year of age. Weight mattered more: men with a BMI of 30 or more had total testosterone about 5.1 nmol/L lower than men under 25, and long-term illness lowered it too.[3] That is why UK guidance doesn’t shift its threshold with age: a man of 65 with 7 nmol/L is low, and a man of 25 with 7 nmol/L is low too.[1]
Your genes set part of your baseline
Your natural testosterone and SHBG are partly inherited. Large UK Biobank studies have linked hundreds of genetic variants to them, several near the SHBG gene.[4] A blood test tells you today’s level; a DNA test reads the variants behind it.
Questions
What is a normal testosterone level for a man in the UK?
The British Society for Sexual Medicine's 2023 UK guidance says total testosterone below 12 nmol/L, or calculated free testosterone below 0.225 nmol/L, usually needs treatment when there are symptoms, and above 12 nmol/L does not. Below 8 nmol/L is clearly low. Laboratories print their own reference range, often from about 8 or 9 up to about 30 nmol/L, on each report.
Do normal testosterone levels change with age?
The average falls slowly from middle age: in the European Male Ageing Study free testosterone fell by about 3 pmol/L a year in men aged 40 to 79, while obesity lowered total testosterone by around 5 nmol/L. UK guidance still uses the same 12 nmol/L line at every adult age, because symptoms and a confirmed low level, not age, decide whether treatment helps.
What time of day should testosterone be tested?
In the morning, ideally between 7 and 11am, and fasting if possible. Testosterone is highest in the morning, and a low result should be repeated on a second morning before anything is decided.
What if my result is between 8 and 14 nmol/L?
UK guidance says men with symptoms between 8 and 14 nmol/L may be offered a trial of treatment for at least six months. Free testosterone, calculated from SHBG and albumin, helps: below 0.225 nmol/L supports treatment. Add your SHBG above to see it.
What does a very high testosterone result mean?
A total above the top of the usual range is common while taking testosterone or other androgens, and can have other causes. Some anabolic steroids are not picked up by testosterone tests at all and instead lower natural testosterone. A GP is the right person to interpret it.
Does this work for women?
No. Women's testosterone is much lower and uses different ranges. This checker uses thresholds for adult men.
Sources
- Hackett G et al. British Society for Sexual Medicine guidelines on adult testosterone deficiency, with statements for practice. World J Mens Health 2023;41:508–37.
- Travison TG et al. Harmonized reference ranges for circulating testosterone levels in men of four cohort studies. J Clin Endocrinol Metab 2017;102:1161–73.
- Wu FCW et al. Hypothalamic-pituitary-testicular axis disruptions in older men are differentially linked to age and modifiable risk factors: the European Male Aging Study. J Clin Endocrinol Metab 2008;93:2737–45.
- Ruth KS et al. Using human genetics to understand the disease impacts of testosterone in men and women. Nat Med 2020;26:252–58.
Keep reading
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Free testosterone calculator
Free and bioavailable testosterone from total testosterone, SHBG and albumin, using the Vermeulen formula.
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Convert testosterone, oestradiol, DHT, prolactin and other results between UK (SI) and US units.
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DNA test vs blood test
What a blood test and a genetic test can each tell you about your hormones, side by side.
For information only, not medical advice. GeneticEdge does not recommend or endorse anabolic steroid use, and no genetic test can tell you whether steroids are safe for you. Talk to a GP or pharmacist about your health. Last reviewed 30 October 2026.